LECTURE 1:
HISTORY OF COMPARATIVE
COGNITION;
ANTHROPOMORPHISM
Psychology 2210B
January 6th, 2025
Instructor: Krista Macpherson, PhD
Course Information
• 3 lecture hours per week, 0.5 course
• Textbook: Olmstead, M.C., & Kuhlmeier, V.A. (2015),
Comparative Cognition. Cambridge University Press.
Evaluation
• Exam 1: 30% of final grade (Feb 3rd, in class)
• Exam 2: 30% of final grade (March 10th, in class)
• Final Exam (TBA): 35% of final grade
• Participation: 5% of final grade
-Participation questions asked in class weekly,
starting next week. Lowest 2 scores dropped,
therefore NO accommodations
Lecture 1: History of Comparative
Cognition
Overview
• Terminology
• Animal Learning vs. animal cognition vs. comparative cognition?
• Overview of Historical Figures
• Other related disciplines
• Ethology, Behavioural Ecology, Behavioural Neuroscience, etc.
What is Learning?
• Domjan (2015, p.14): Learning is an enduring change in the
mechanisms of behaviour involving specific stimuli and/or
responses that results from prior experience with those or
similar stimuli and responses.
• Learning plays a critical role in improving how organisms adapt to their
environment.
• Learning, like physiological responses (ex: breathing) are key to an animal’s
survival.
• Learning can involve making OR inhibiting responses (ex: learning NOT to
drive at a red light).
• May or may not require an explicit teacher (learning your way around a new
neighborhood vs. learning to drive a vehicle).
Animal Learning vs. Animal Cognition
• Animal Learning: How animals acquire new behaviours
(often discussed in the context of classical and/or operant
conditioning)
• Animal Cognition: Can be thought of as an extension of
animal learning, often addressing higher order cognitive
abilities. For example, how do animals use the
information they obtain from their environment to move
through space, time their activities, assess quantity, or
remember the past?
• Comparative Cognition: Comparing cognitive ability of
different species (often human vs. non-human animals),
evolutionary lense.
History of Animal Learning
• Before Descartes, prevailing philosophy was
that human behaviour is entirely controlled by
conscious intent/free will.
• Descartes countered this idea with “Cartesian
Dualism”
• Two classes of human behaviour—voluntary
and involuntary
• Involuntary behaviours are reflexes triggered
by external stimuli.
• Voluntary behaviour is the product of
conscious intent
René Descartes
(1596-1650)
Cartesian Dualism
• Descartes believed that the involuntary behaviour was the
only one available to non-human animals…so all
behaviour in non-human animals was reflexive.
• Free will and voluntary behaviour considered
uniquely human traits (because humans believed to
have a mind and/or soul)
• The mind is a non-physical entity, connected to brain via
the pineal gland, which allows for voluntary behaviour
independent of external stimulation.
Nativism
• Descartes believed that the mind contained ideas that
were innate and existed in all human beings independent
of personal experiences.
• These innate ideas included the concept of God, the
concept of self, and basic geometric principles.
• The philosophical approach that we are born with certain
innate ideas is referred to as nativism.
Empiricism
• Some philosophers after
Descartes took issue with the
idea of nativism.
• John Locke put forward idea
that people are born with no
preconceptions about the
world…we are born with a clean
slate or “tabula rasa”
• The idea that we acquire our
ideas and information as we
experience the world is referred
to as empiricism.
John Locke (1632-1704)
Ebbinghaus & Rules of Association
• Hermann Ebbinghaus tested how
association are formed, using nonsense
syllables. He used himself as a subject!
• Ebbinghaus studied lists of nonsense
syllables (ex: PZD, KOJ) under various
experimental conditions, then tested his
ability to recall them.
• Allowed him to determine if the strength of
association increased with training, if items
close together are associated more closely
than those far apart, backwards and
forwards associations.
Hermann Ebbinghaus
(1850-1909)
“Dawn of the Modern Era”
• Research in animal learning and behaviour became of
interest just over 100 years ago.
• Three reasons for this interest:
• 1. Interest in comparative cognition and evolution
of the mind.
• 2. Interest in how the nervous system works (functional
neurology)
• 3. Interest in developing animal models (to study
aspects of human behaviour)
1. Interest in Comparative
Cognition/Evolution of the Mind
Charles Darwin (1809-1882)
Darwin’s Theory of Evolution
• Tenets of Natural Selection:
• Variation (individuals within a species display
differences in both physiological and behavioural
traits)
• Heritability (Offspring inherit traits from their parents)
• Survival and reproduction (individuals with traits
that best promote survival have best chance of
transmitting traits to offspring)
• A premise of comparative cognition is that cognitive
traits are shaped by the same selective pressures
Speciation
• When populations of
a single species get
separated, they
adapt to their new
environment.
• Speciation occurs
when the groups
diverge to the point
that they can no
longer interbreed.
Continuity Hypothesis
• Darwin theorized that trait differences between humans and
animals are quantitative, not qualitative
• So, humans and animals may differ greatly in ability, but the
difference is not in trait…rather it is how the trait is expressed.
• According to Darwin, animals possess some, if not all,
cognitive and emotional traits that humans have, even if only at
an incipient level.
• Modern comparative psychologists do not assume that animals
have all human traits. Rather, we test such hypotheses
experimentally!
Evolutionary Tree
Darwin vs. Descartes
• *Ideas about 250 years apart*
• Descartes had proposed that human’s shared some
behavioural similarities (ie: reflexes) with animals, but
maintained that humans were unique in having a mind.
• Darwin believed in not only the evolution of physical traits, but
also the evolution of psychological/mental abilities.
• Darwin believed that animals, like humans, had the
capacity for wonder, curiosity, imitation, attention, memory
etc.
• Darwin collected anecdotal accounts of animal intelligence
(More on this in later!).
I
Research article Open Access
I Published: 09 June 2020
Teaching evolution in U.S. public schools: a
continuing challenge
Eric Plutze r B, Glenn Branch & Ann Reid
Evolution: Education and Outreach 13, Article number: 14 (2020) I Cite this article
8 4 8 9 Accesses
I 1 Citations I 94 Altmetric I Metrics
Abstract
Background
Over a decade ago, the first nationally representative probability survey concerning the
teaching of evolution revealed disquieting facts about evolution education in the United
States. This 200 7 sur ve y found that only about one in three public high school biology
teachers presented evolution consistently with the recommendations of the nation's
leading scientific authorities. And about 13% of the teachers emphasized to their
students that creationism was a valid scientific alternative to modern evolutionary
biology. In this paper, we investigate how the quality of evolution teaching, as measured
Gustave Fechner (1801-1887)
• German philosopher and scientist,
professor of physics.
• Student of Weber, who was critical in
understanding differences in subjective
experience
• Created formal equations based on
Weber’s observations.
• Formalized the scientific measurement
of perception (psychophysics), which
paved the way for experimental
psychology (which was started by
Wundt).
Other key figures in animal learning…
(These guys basically get their own chapter in the textbook,
so we’ll come back to them!)
2. Functional Neurology
• Uses studies of learning/behaviour in nonhuman animals
to gain insight into how the nervous system works.
• Influenced greatly by Ivan Pavlov and his belief in
nervism.
• Highly influential in modern neuroscience
• Lynch et al (2003, as cited in Damjan (2015)):
“neuroscience is a large field founded on the premise that
all of behaviour and all of mental life have their origins in
the structure and function of the nervous system” (p.xvii)
3. Animal Models of Human Behaviour
• Belief that studying non-human animal behaviour may help us
understand human behaviour.
• Typically done with primates, pigeons, rats, and mice. We do
NOT assume that these animals are exactly like humans.
• Models permit investigation under conditions that are less
expensive, simple, easy to control, or would otherwise be
impossible with humans.
• Must decide what the relevant features are of the subject of
interest, and make sure the animal model is similar.
• Crucial in drug development.
Related Areas of Study--Ethology
• Flourished in Europe in the early to mid-twentieth century.
• Based on premise that study of behaviour should be
naturalistic.
• Lab experiments may be used for better control of
observation, but natural conditions should be recreated in
order to measure responses that are part of the animal’s
behavioural repertoire.
• Focus is on evolutionary explanations for behavioural
traits.
Fixed Action Patterns (FAPs)
• Konrad Lorenz, Nikolaas Tinbergen, and Karl von
Frisch famously studied instincts, or “innate” responses
hard- wired (not learned) by different species.
• Lorenz (1950) and Tinbergen (1951) developed the
concept of Fixed Action Patterns. FAPs are
stereotyped, species-typical behaviours that occur in a
rigid order and are triggered by stimuli in the environment.
• Ex: egg rolling in graylag geese, regurgitation in herring
gulls
Egg Rolling in Greylag Geese
Herring Gull Feeding Chick
Imprinting (Lorenz, 1952)
• Innate responses are not necessarily fixed.
• FAPs can be modified by experience—behaviour must
therefore be understood as an interaction between
learning and inherited mechanisms.
• Lorenz demonstrated that young birds learn the
characteristics of the first moving object they encounter,
and follow it around.
• Chicks imprinted on the first suitably sized, moving object
they encounter. This happens within 13-16 hours of
hatching.
Imprinting (Lorenz, 1952)
Environment always plays a factor…even with seemingly “hardwired” responses!
Four Questions of Ethology
• Tinbergen proposed that behaviour should be analyzed in
terms of four scientific questions:
Adaptive value (What is the function of behaviour)
2. Evolution (How did the behaviour develop across evolution
and how does it compare to closely related species)
3. Ontogeny (How does the behaviour change across the
lifespan of the organism?)
4. Immediate causation (What are the internal mechanisms
that produce the behaviour)
1.
The first two questions are ultimate causes of behaviour, the
second two are proximate causes of behaviour.
Related Areas of Study--Behavioural Ecology
• Lorenz, Tinbergen, and von Frisch shared the Nobel Prize in
Physiology or Medicine in 1973.
• In the mid to late 20th century, however, many scientists became
uncomfortable with ethology’s focus on FAPs and the behaviour of
individual organisms…many animals live in social groups!
• In response, Behavioural Ecology was developed…the scientific study
of the evolutionary basis for animal behaviour due to ecological
pressures.
• Behavioural ecologists study the interaction between organisms and
their environment, and how these interactions result in differential
survival and reproduction.
Emergence of Comparative Cognition
• Comparative cognition grew out of behaviourism (from the
field of psychology) and behavioural ecology (from the field of
zoology).
• These two fields worked mostly independently for 50 years,
even though scientists from both disciplines were often asking
the same questions.
• Starting in the 1960’s and 1970’s, a synergy of these two
perspectives emerged (more psychologists doing field work,
more behavioural ecologists doing lab work)
• Most importantly, an understanding that both proximate and
ultimate causes of behaviour must be considered when
understanding any behaviour or cognitive process.
A Side Note about Behaviourism…
• Behaviourism was the dominant school of thought in psychology
for much of the first half of the 20th century, until the cognitive
revolution.
• Hull, Thorndike, Watson, & Skinner all very influential in this
movement.
• Behaviourism maintained that only observable and
measurable behaviours should be studied in psychology.
• In reality, many psychologists realized that mental processes
exist, and instead practiced “methodological behaviourism”.
• More on this topic in future lectures!
Insight Learning? (Kohler, 1927)
Other Related Areas of Study
• Developmental Psychology
• Comparative cognition benefits from the fact that
developmental psychology has a long and established
tradition of examining changes in cognition experimentally.
• Non-human animals and young human infants have
something in common: they are both non-verbal!
• Behavioural Neuroscience
• Neuroscience techniques can be used to study underlying mechanisms
of cognition.
• Examines brain systems via lesions, electrical stimulation,
pharmacology, and brain imaging.
Ethics in Animal Research
• Non-human animals do not choose and cannot consent to
participate in research.
• Strict ethical protocols therefore exist to ensure that
research animals are treated with the least amount of
invasiveness possible.
• Ethical standards have evolved and become stricter over
time (for both human and animal subjects).
• Good science requires good animal care.
Summary:
• The field of comparative cognition studies a wide diversity
of species, uses a variety of methodologies, and is
studied in a number of different academic departments.
• Nevertheless, three unifying hallmarks include:
• Focus on cognition (acquisition, storage, and
processing of mental info)
• Use of experimental methodology (either in lab or
natural environment)
• Explanation of findings within framework of
evolutionary theory.
Course Objectives This Semester:
Thinking critically about animal intelligence!
More specifically:
• Describe and explain key findings and concepts in animal cognition
• Summarize the history of animal cognition research, and understand its
contributions to various disciplines
• Explain our current understanding of cognitive ability in a number of
species, as well as evolutionary pressures which have shaped these
abilities.
• Understand how to formulate testable hypothesis about animal cognition
and behaviour.
• “higher level” vs. “lower level” explanations for behaviour
• Ex: Kohler’s chimps—insight? Or Trial and error?
NEXT UP:
ANTHROPOMORPHISM—
THINKING ABOUT HOW
ANIMALS THINK
What is Anthropomorphism?
• A really cumbersome word
to pronounce!
• The attribution of human-
like characteristics to nonhuman animals or objects.
• Important to consider in
understanding animal
behaviour and cognition.
Historical Figures: Darwin
• Darwin believed in not only the
evolution of physical traits, but also
the evolution of psychological
abilities.
• Darwin believed that animals, like
humans, had the capacity for
curiosity, imitation, attention,
and memory.
• Darwin collected anecdotal
accounts of animal
intelligence…his interest in these
types of research questions was
extremely influential.
Charles Darwin (1809-1882)
Historical Figures: George Romanes
• Initially a research
assistant to Darwin,
George Romanes, was
also interested in
questions of animal
intelligence.
• Using an anecdotal
method, he was the first to
investigate systematically
the comparative
psychology of intelligence.
George Romanes (1848-1894)
An Example of the “Anecdotal Method” (Romanes,1888, p.48):
“Several ants passed it, but at least one discovered it and
tried to pull it out, but could not. It immediately set off at a
great rate, and I thought it had deserted its comrade, but it
had only gone for assistance, for in a short time about a
dozen ants come hurrying up, evidently fully informed of
the circumstances of the case, for they made directly for
their imprisoned comrade and soon set him free.”
“The next that approached, as soon as it discovered its
situation, ran backwards in an agitated manner, and soon
communicated the intelligence to the others. They rushed to
the rescue; some bit at the stone and tried to move it, others
seized the prisoner by the legs and tugged with such force
that I thought the legs would be pulled off, but they
persevered until they got the captive free.”
Historical Figures: C. Lloyd Morgan
• In 1894, C. Lloyd Morgan published
Introduction to Comparative
Psychology.
• Morgan drew a distinction between:
A.) Objectively testable inferences
from animal behavior, which were
scientific.
Vs.
B.) Untestable speculations about
animal minds, such as Romanes’
anecdotally based inferences, which
were not scientific.
C. Lloyd Morgan (1852-1936)
Tony the Terrier
• Morgan had a terrier named
Tony, who was adept at opening
a gate in order to let himself out
of the yard.
• To many, this might appear to be
insightful behaviour on Tony’s
part.
• Morgan observed Tony’s
behaviour and was able to
demonstrate that it was instead
the result of trial-and error
learning.
Morgan’s Canon
• Prompted by Romanes’ tendency to rely on anecdotal
evidence rather than empirical tests.
"In no case is an animal activity to be interpreted in
terms of higher psychological processes, if it can be
fairly interpreted in terms of processes which stand
lower in the scale of psychological evolution and
development” (Morgan, 1894, p.53)
•.
The Cautionary Tale of Clever Hans…
• Hans was a horse owned
by Wilhelm Von Osten.
• Von Osten claimed that
Hans could add, subtract,
multiply, divide, work with
fractions, tell time, keep
track of the calendar,
differentiate musical tones,
read, spell, and understand
German.
• Hans was most famous for his mathematical ability…if Von Osten
asked him what “4+4” was, for example, Hans would stomp his
hoof 8 times in response.
“Clever Hans Cues”
• Eventually, it was determined
that Hans was simply
responding to very subtle
changes in Von Osten’s
posture to solve the problem.
• Importantly, Von Osten was
not trying to trick anybody—
he genuinely believed in
Hans’ abilities and had no
idea that he had been cueing
him!
• In designing behavioural experiments with animals, we are
now very careful to avoid “Clever Hans Cues”
Recall..Köhler (1913)
Question…
• How can we empirically study
anthropomorphism?
Dog Heroes?
• Stories are frequently
reported of dogs who
have “rescued” their
owner from imminent
danger (drowning, fire,
heart attack, choking,
etc).
• In these stories, dogs often seek help for the owner
by alerting a bystander to the danger.
Wonder dog is all golden*Woman claims pet pooch
gave her the Heimlich
By Scott Goss sgoss@cecilwhig.com | Posted: Tuesday, March 27, 2007 1:00 am
A Calvert woman claims her 2-year-old golden retriever
saved her life Friday by giving her the canine version of
the Heimlich maneuver.
“The doctor said I probably wouldn’t be here without
Toby,” said Debbie Parkhurst, 45, a jewelry artist who
lives near Rising Sun High School with her husband,
Kevin, and their two dogs. “I keep looking at him and
saying ‘You’re amazing.’”
Parkhurst said she was home alone with the dogs Friday
afternoon when she decided to snack on an apple.
Suddenly, she said, a chunk of the fruit became wedged in
her windpipe.
“It was lodged pretty tight because I couldn’t breathe,”
she said. “I tried to do the thing where you lean over a
chair and give yourself the Heimlich, but it didn’t work.”
Parkhurst said she then began beating her chest, an action
that might have attracted Toby’s attention.
“The next think I know, Toby’s up on his hind feet and
he’s got his front paws on my shoulders,” she recalled.
“He pushed me to the ground, and once I was on my back,
he began jumping up and down on my chest.”
Toby’s jumping apparently managed to dislodge the apple
from Parkhurst’s windpipe.
Wonder dog is all
golden*Woman claims pet pooch
gave her the Heimlich
Debbie Parkhurst and her dog Toby, the 2year-old golden retriever who she claims
saved her life by performing a doggy
version of the Heimlich, to dislodge a piece
of apple stuck in her windpipe.
“As soon as I started breathing, he stopped and began
licking my face, as if to keep me from passing out,” she said.
A friend soon arrived and, after witnessing the canine rescue, drove Parkhurst to the doctor’s office.
Will Dogs Rescue an Owner in “Distress”
• Scenario staged in which dog’s owner feigns having a
heart attack.
• One or two bystanders available from whom the dog
could seek help…this paradigm was borrowed from
bystander apathy studies in social psychology (Darley &
Latané, 1969)
• Dog is filmed for 6 minutes for its reaction once the owner
collapses
• N=12 dogs of various breeds, handled by their owners.
Experiment 1—Heart Attack Scenario
Pylon
Pylon
Bystander 1
Tree
(Camera)
Target
(Victim)
Pylon
Bystander 2
Pylon
Video-Experiment 1
Mean frequency
of behaviours
Mean duration of
behaviours
Experimental Design:
• What are the limitations of Experiment 1 in the
Macpherson & Roberts (2006) study?
• What might we consider in designing a follow-up
study?
Experiment 2—Bookcase Scenario
• After being introduced to a bystander in a nearby room
(but not in plain sight), dog owners pretended to have a
bookcase fall on them, supposedly injuring them and
trapping them beneath the fallen bookcase. For 6
minutes, they appealed to their dogs for help.
• In a control group, owner stood quietly at the bookcase
reading a book. No “emergency” occurred.
• N=30 dogs of various breeds.
•
Experiment 2—Bookcase Scenario
Video—Experiment 2
Mean Frequency of Behaviours
Mean Duration of Behaviours
Conclusions
• So does Lassie go get the sheriff?
• Nope, Timmy is stuck in that well!
• Are dogs ever heroes? Absolutely!
• Guide dogs, CARDA, police dogs etc.
The “Guilty” Look in Dogs (Horowitz, 2009)
• Owner leaves their dog
alone in a room with a
desirable treat on the floor,
but commands dog not to eat
it.
• Trials varied both the dog’s
opportunity to eat the treat,
as well as the owner’s
knowledge of what the dog
did in their absence.
Innocent Until Proven Guilty!
• Dogs who ate the treat were no
more likely than dogs who did
not to display the “guilty look”.
• Dogs who were scolded were
more likely to display guilty
look, especially if they had
been obedient.
• Guilty look is likely a response
to owner cues, rather than an
acknowledgement of a
misdeed.
What’s wrong with Anthropomorphism?
• Nothing—if you are not referring to it within a scientific
context.
• From an animal welfare perspective, anthropomorphism
may result in better treatment of animals.
BUT…
• In a scientific context, anthropomorphism can cloud our
judgement, or make us too liberal in what abilities we are
willing to attribute to animals.
Video: Tool Use in New Caledonian Crows
Why is Betty so Important for
Understanding Tool Use?
• Betty was wild caught as a juvenile (no other crows to
model)
• No experience with wire in the wild
• No training with pliant/bendable objects in lab
• Spontaneous problem solving (Abel took the hooked wire,
leaving Betty with only the straight wire).
• Novel and purposeful behaviour, which cannot be
explained by associative learning!
In Conclusion…Anthropomorphism is:
• The attribution of human-like qualities to non-
human animals or objects.
• Possibly a good (and fun!)
thing in day-to-day life.
BUT…
• Something we need to be extremely vigilant of
in the scientific study of animal behaviour and
cognition.
LECTURE 2:
SENSATION & PERCEPTION
Psychology 2210B
Instructor: Krista Macpherson, PhD
Date: January 13th, 2025
Part 1: Sensation
• Evolution of Sensory Systems
• Development of Sensory Systems
• Sensory System Function
Part 2: Perception
• Interpretation
• Measurement (psychophysics!)
• Stimulus Filtering/Attention
• (if we have time…if not next week)
A few questions…
• What colour is the sky?
• Which is warmer…fire or ice?
• Which tastes sweeter…sugar or vinegar?
• Which smells stronger…burning wood or burning rubber?
• Which is louder…the chirp of a bird, or the crack of a rifle?
• In short…how do you know anything about your world?
• The world is a “black box” without sensation/perception
• There is not cognitive world without the experience of
sensation/perception
The five senses…
• Vision
• Those other 4?!
• Hearing
• Touch
• Taste
• Smell
• Without these five senses, our brains would not be able to
process anything about our world.
Sensation vs. Perception
• Sensation: The process through which the senses pick
up visual, auditory, and other sensory stimuli and transmit
them to the brain; sensory information that has registered
in the brain but has not been interpreted.
• Perception: The process by which sensory information is
actively organized and interpreted by the brain.
Humans are extremely reliant
on the visual system
(hence our bias towards it)
…this often is not the case
for non-human animals!
What is it like to be a Bat?
• Philosophical paper by Nagel (1974)
• Is it possible to understand another species’ experience?
• Bats use echolocation, for most humans, this is something we never
experience.
• Most animals possess some sensory ability that is absent in humans
• birds are thought to use earth’s magnetic field to migrate
• Mantis shrimp detect polarized light
Echolocation
Brain Activity in Echolocator vs. NonEcholocator Human
The Boy Who Echolocates
Mantis Shrimp
(Visible Light Spectrum)
Why is understanding Sensory Systems Important?
• All cognitive processes are influenced, at least initially, by
sensory input.
• This makes the understanding of sensory system evolution,
development, and function across species very important.
• Sensory systems provide the first point of contact between
an organism and its environment.
• Need to understand:
• 1. Evolution
• 2. Development
• 3. Function
1. Evolution of Sensory Systems
• Humans see vibrant colour in flowers, but not UV
reflections which guide insects.
• Humans detect odor, but could not track another human
or animal like a dog.
• Human auditory systems is finely tuned to range of sound
frequencies in speech, an advantage for verbal
communication.
• Visual information is also extremely important for humans,
so we have evolved a complex visual system.
(Approximate values)
• “Henry’s Pocket” is the
name of the slit in the ears
of dogs, cats and some
other animals…it is thought
to help them hear sounds
of higher frequencies.
Visual Adaptation
https://www.youtube.com/watch?v=myh5WjGTc8U
Star-nosed mole
Visual Adaptation
• In all animals, the visual system works by absorbing light
of particular wavelengths along the electromagnetic
spectrum.
• Humans see within 400-700nm range, because we have
pigments in the eye to absorb these wavelengths.
• Different animals in different habitats have evolved
different visual sensitivities.
• Evolution has also favoured
traits that help animals see
based on different lifestyles.
• Compared to diurnal animals,
nocturnal animals have larger
lenses that pick up more light.
• The tapetum lucidum (located
behind the retina) also aides in
the night vision of many
animals, particularly nocturnal
animals.
Eye Placement
• Binocular vision occurs when the two
visual fields overlap.
• The brain uses the disparity between
the right and left eye to create depth
perception, or stereopsis.
• Prey animals tend to have laterally
placed eyes, resulting in less depth
perception, but an extremely large field
of view.
• Predators tend to have more forward-
facing eyes, resulting in excellent depth
perception, but very poor lateral vision.
Timney & Keil (1999)
• Stereopsis in Horses
• Horses have laterally
placed eyes...do they have
enough binocular overlap
to detect depth perception?
• Horses successfully trained
to discriminate flat (+)
stimulus from protruding (-)
stimulus.
Rods, Cones, and Retinal Ganglion Cells
• Rods and cones are photoreceptors at the back of the eye
that detect light and colour.
• Rods = Better Night Vision
• Cones = Better Colour vision
• Nocturnal animals tend to have far more rods than diurnal
animals.
• Rods are 1000x more sensitive to light than cones
• nocturnal animals navigate very well in the dark but often have inferior
colour vision.
• Retinal Ganglion cells are neurons that are the “last stop” in
the eye
• information from the photoreceptors in the retina is passed to the optic
nerve and sent to the brain.
Human Vision vs. Dog Vision
(Treat the below numbers as approximations, as slightly different
numbers have been reported)
• Humans (diurnal):
-0.7-1.5 million retinal ganglion cells
-4.6 million cones
-92 million rods
-trichromat colour vision
- have densely packed cones in the fovea, which is
responsible for sharp central vision.
Dogs (arrhythmic diurnal…NOT nocturnal):
-115, 000 retinal ganglion cells (Peichl, 1992)
-Far more rods than cones
-dichromat colour vision
-Retinal Ganglion Cells arranged in “visual streak”
Human Fovea
Visual Streak in the Dog (Peichl, 1992)
German Shepherd
Beagle
Pigeon Retina (Double Fovea)
Sensory Adaptation in Closely Related Species…
• Snakes can detect chemical, visual, and thermal cues, but
they may show greater sensitivity depending on their
preferred prey.
• The Midland rat snake feeds on rodents, and responds to
chemical cues allowing them to follow odour trails.
• Western fox snakes respond more to visual cues in order
to hunt ground nesting birds.
Sensory Drive Hypothesis
• Explains divergence of
sensory abilities both
between and within
species.
• Facilitates communication
• Developing different sensory
abilities either between or
within species is costly, so
these capacities are lost or
not developed unless needed
Sensory Drive Hypothesis:
• Animals become separated by a geographical barrier (ex: mountain
range).
• New habitat has features that make it easier or harder to
communicate in the old territory.
• Ex: If birds move into a territory with denser trees, lower light would
make it difficult for females to detect bright plumage on males.
• Therefore, females with better visual acuity and males with brighter
feathers, have new advantage that was not present in old habitat.
• Birds of Paradise:
• https://www.youtube.com/watch?v=YTR21os8gTA
Birds of Paradise
Sensory Bias
• A paradox of the evolution of
sensory systems.
• Occurs in situations in which
individuals of a species
respond with increased
vigour to stimuli that are
exaggerated versions of
naturally occurring stimuli.
• Ex: Experiments using
artificial tails in Paradise
Whydah
Sensory Exploitation
• When sensory signals which
were important for one
process have been co-opted
by another.
• Female Zebra finches need
white feathers to build nests.
Their interest in the adorned
males has nothing to do with
male fitness, but rather is a
“borrowed” response from
their nest building behaviour.
Supernormal Stimuli
• The principles of sensory exploitation may also explain
heightened responses to exaggerated versions of natural
stimuli.
• Tinbergen (1951): graylag geese
retrieve and attempt to incubate
giant artificial eggs
• even when their actual eggs sat
nearby.
• Stickleback fish will ignore
invading conspecifics in favour of
attacking wooden dummy fish
with darker red undersides.
Recall from Lecture #1…
Tinbergen (1951)
In Summary…
• an enormous range of sensory abilities existis across the
animal kingdom.
• All animals experience only a portion of the sensory
world, and these generally reflect the evolutionary history
of that species.
2. Development of Sensory Systems
• Much of what is known regarding sensory system development comes
from pioneering work by Hubel & Wiesel (who won the 1981 Nobel
prize for their description of how the visual system is processed and
organized in the brain).
• Found that when young monkey or kittens are deprived of vision for as
little as 1 week, normal vision never develops.
• BUT…visual deprivation for weeks or even months in adults has no effects on vision.
• Cells in the eye respond normally after deprivation, however neurons in
the cortex that receive signals from these cells do not.
• Sensitive Period: The period in which experience-dependent changes
can have profound and enduring effects on development.
Blakemore (1976)
• If cats are exposed to a particular visual
stimulus during the first few weeks of life
(horizontal versus vertical lines), their
ability to detect the previously exposed
pattern is enhanced in adulthood.
• This shift in sensitivity occurs because
connections between neurons in the
visual cortex are rearranged during
development, and these cortical neurons
become more responsive to the familiar
pattern.
• Sensitive periods have been shown in
cognitive processes such as
categorization, social competence,
and communication.
Compensatory Plasticity Hypothesis
• If sensory input (ex: vision, audition) is blocked during
development, the functioning of that system may be
blocked in adulthood.
• Deficits in one sensory system may lead to enhanced
ability in another sensory system.
Chapman et al. (2010)
• Guppies raised under different light intensities, then tested for how
they responded to light or olfactory cues.
• Fish raised under high light intensity respond better to visual stimuli,
fish raised under low light respond better to olfactory cues.
• Compensatory Plasticity Hypothesis: A loss or deficit in one sense
results in heightened capacity in another.
• Whereas natural selection is a slow process requiring many
generations, compensatory plasticity allows animals to adapt, within
their lifetime, to a new environment.
In Summary…
• Most animals do not have fully functioning sensory
systems at birth.
• Both normal development and fine tuning of sensory
abilities depend on postnatal sensory experience.
• Nature AND Nurture!
3. Sensory System Function
• Two stages: detection and processing
• Sensory Detection: How animals acquire information
about their sensory world.
• Sensory Processing: How information is organized and
transmitted to other brain regions.
• Helps animals interpret the world around them, and
respond appropriately.
Sensory Detection
• Begins at the sense organs (eyes,
ears, nose, skin, tongue), each of
which contain sensory receptors.
• Sensory receptors transmit info to
Central Nervous System, through
neuronal communication.
• Action Potential: The
transmission of an electrical signal
from soma, along axon, to
presynaptic terminal, resulting in
release of neurotransmitters
(neuron is “firing”)
Transduction
• Sensory receptors respond not to neurotransmitter
release, but to input from the environment.
• This input arrives as a physical event (sound waves, light
waves, airborne chemicals)
• When these physical stimuli reach the sense organs,
sensory receptors are activated and fire action potentials.
• This process of taking this physical input and translating it
into electrical signals/neuronal messages is called
transduction.
Sensory Processing
• Sensory information remains separated by modality as it
is sent from the sense organs to the brain.
• This is because there are separate neuronal pathways for
vision, hearing, olfaction, etc.
• This ensures that messages do not get “scrambled” as
they are sent to the appropriate brain region.
• Scent/taste most ancient
• Visual system most complex
© Cambridge University Press 2015
Summary:
• All cognitive processes are influenced at least initially by
sensory input.
• Sensory systems are the first point of contact between
an organism and their environment.
• While humans rely heavily on vision, other species have
adapted to their respective environments.
• Sensory information is transmitted to the central nervous
system and on to different brain regions where is it
processed and interpreted (ie: perception)
Next up…Perception!
• In the first half of the lecture we talked about how sensory
information is detected, segregated, and transmitted
• but this is only the first step in understanding how animals interact
with their environment!
• Sensations: Produced when when physical stimuli
activate sensory receptors, which then send neural
circuits through specialized circuits.
• Perception: The interpretation of these signals which
occurs when sensory information is processed, organized,
and filtered within the central nervous system.
• In the below picture, sensory receptors detect a series of
black dots and random shapes.
• Perception allows us to see the spotted Dalmatian.
”The Dress”
Psychophysics
• The study of the relationship between sensations and
perception is called psychophysics.
• Conducted by asking participant to indicate when they
see a light, hear a sound, smell an odor, etc.
• ex: hearing tests
• BUT…animals can’t make verbal responses…so how do
we test them?
Psychophysics with Non-Human Animals
• Basically, we need to find a way to get a yes/no response
from an animal.
• The easiest way to do this is by training the animal to
make one response when a stimulus is present (S+), and
another response when the stimulus is not present (S-).
• By varying the intensity of the stimulus, the researcher
can determine the point at which the animal can no longer
perceives the stimulus.
Ernst Heinrich Weber (1795-1878)
• German Physician
• Noted that “in observing the
disparity between things that are
compared, we perceive not the
difference between the things, but
the ratio of this difference to the
magnitude of things compared.”
• In other words…we are able to
distinguish the relative difference, not
the absolute difference between
items.
Gustave Fechner (1801-1887)
• German philosopher and
scientist.
• Concerned with how a person’s
subjective experience could be
measured scientifically.
• Student of Weber; created
formal
equations based on Weber’s
observations.
Fechner’s “Three Problems” of Psychophysics:
• Detection: Find a way to measure the minimum amount
of a stimulus that could be detected (ie: absolute
threshold).
• Discrimination: Find way to determine how different two
stimuli must be in order to be detected (ie: difference
threshold/JND).
• Scaling: Find a way to describe the relationship between
the intensity of the stimulus and the intensity of our
sensation (ie: Fechner’s Law).
Detection--Absolute Threshold
• Question: How much of an energy change, starting from
zero, is required for a subject to sense it?
• Below some level of intensity, a subject will not be able to
detect it. As soon as the threshold intensity is exceeded,
the subject can be expected to always detect it. This is
known as the Absolute Threshold.
• Absolute Threshold is not fixed!
Psychometric Function
Subject’s
Perception
Intensity of Stimulus…could be sound, light, heat etc.
Psychometric Function
If we plotted proportion
of “No” responses
Subject’s
Perception
Intensity of Stimulus…could be sound, light, heat etc.
Dark Adaptation
• Dark adaptation is the lowered threshold for detecting
light that occurs under reduced illumination.
• Takes a few minutes to develop because it involves a
series of neurochemical reactions in the eye.
• Evolved in some humans and animals, providing ability to
see during day and night.
• Provides evidence that perceptions are not a direct
reflection of sensations.
Blough (1956)
Birds in operant chamber must peck S+ if
they detect light, and S- if they do not.
Threshold to detect light is much lower the
longer they are kept in a dark environment.
Methodology
What methods could we use to measure absolute
threshold?
1. Method of Constant Stimuli
2. Method of Limits
3. Adaptive Testing
Method of Constant Stimuli
• Uses a fixed number of stimuli of various intensities.
• Each stimuli presented many times in different orders.
• Subject response “yes” when stimuli is detected and “no”
when it is not.
• S-shaped curve is usually found for all sensory systems
when using Method of Constant Stimuli.
Method of Constant Stimuli
“What Actually Happens”
Psychometric Function
Theoretical Psychometric
Function
Method of Limits
• Focus only on stimuli near the absolute threshold
• Descending series: Experimenter starts with easily detected
stimuli, decreases intensity until subject can no longer perceive it.
(Start above threshold, go down until stimulus not perceived)
• Ascending series: Experimenter starts with stimuli that cannot
be perceived, increases intensity until it can be perceived.
(Start below threshold, go up until stimulus is perceived)
Adaptive Testing (Staircase Procedure)
• Method of limits only test stimuli that bracket the absolute
threshold (the last two in the testing series)…all other
stimuli in these sets tell us nothing.
• Adaptive testing keeps the test stimuli “hovering” around
threshold by adapting stimuli based on subjects
responses.
• Threshold is obtained by averaging stimulus intensity
value of the reversals.
Staircase Procedure
Allows
Experimenter to
track changes in
threshold over
times or across
the “track”
Average of
reversal points
will give us the
threshold value
Signal Detection
• All of the detection methods we have talked about so far
involve responses of “yes I perceive it” or “no I don’t
perceive it”.
• Problem—what if the individual wants to appear more
sensitive than they really are?
• Catch trials can help eliminate this problem…in these
trials, no stimulus is presented.
Signal Detection Theory
• Recognizes that any stimulus must be detected amongst
a background of ongoing intermittent noise.
• No absolute threshold, only a series of observations
which must be categorized as ”signal present” or
“signal absent”
• Can be used to determine how sensitive individual is to a
signal, independent of any expectation effects that might
bias decisions.
Outcome Matrix
Target stimulus Presented
Target stimulus not presented
Just Noticeable Difference (JND)
• JND is the amount by which two stimuli must differ so that
the difference can be detected.
• As the intensity of a stimulus increases, so does the
intensity that produces a JND (ex: a dim light turned up
in a dark room is immediately noticeable, whereas a much
brighter light will need much more illumination to produce
a perceptual change).
• The ratio between the current stimulus intensity, and the
intensity change required for a JND is called the Weber
fraction.
Weber’s Law
• Weber's Law says that the size of the just noticeable
difference (i.e., delta I) is a constant proportion of the
original stimulus value.
• Expressed as follows: I = k I
• I is the difference threshold (or JND)
• I is the intensity/magnitude of the standard
• k is a constant, known as the Weber Fraction
• The Weber fraction (k) is equal to I / I
Percentage Correct
Sedona--Overall Performance
100
80
60
40
20
0
0
0.11 0.2 0.25 0.33 0.5 0.67 0.75 0.89
S/L Ratio
Weber’s Law Effects in Monkey (Numerical Task)
1.00
Proportion Correct
0.90
0.80
0.70
Model
Observed
0.60
0.50
Beran (2007)
0.40
0.30
0.20
0.10
0.00
0.1
0.2
0.33 0.5 0.67 0.8
Small/Large Ratio
0.9
Difference Threshold (or JND)
• Asks the question “by
how much must two
stimuli differ in order to be
discriminated as not the
same”.
• We are still measuring a
threshold, but in this case
it is a threshold for the
perception of a difference
between the standard
and comparison stimuli.
Difference Threshold (or JND)
• We can’t take the point where
the comparison stimulus is
considered “lighter” half the
time and heavier half the time
as a threshold—that is the
point where the weights are
judged to be the same (0.5 on
y axis = 99g)…this is the
point of subjective equality
(PSE).
Interval of
Uncertainty
• Instead, we are interested in
the point where heavier/lighter
can be distinguished from the
PSE…this is the interval of
uncertainty (0.25 and 0.75 on
y axis).
PSE
Differences in Discriminative Ability :
Better discrimination =
smaller difference threshold,
and steeper curve
Sensations Transformed to Perception
• Three Stages:
• Sensory info segregated by modality (sound, light, etc.)
• Sensory info coded for stimulus dimensions (duration/intensity)
• Combined into a perceptual whole
Sensations Transformed to Perception
• To understand how information is processed at each
stage of the circuit, scientists implant electrodes in groups
of neurons at each relay station and record how these
neurons respond to different stimuli.
• In the visual system, most of the sensory receptors in the
eye project to a region of the thalamus called the lateral
geniculate nucleus (LGN)
LGN vs. Superior Colliculus
• Superior Colliculus is a visual pathway that does not travel through
LGN.
• 10% of retinal fibres project onto Superior Colliculus…was thought
the be “vestigial” system.
• LGN = the “what” of vision
• Superior Colliculus = the “where” of vision
• For this reason, cortically blind patients sometimes demonstrate
“blindsight” and can tell you where an object is, even though they
claim they cannot see it.
Orbitofrontal Cortex (OFC)
• Receives direct and indirect information from ALL
sensory areas.
• Likely has important role in sensory integration.
• May help assign motivational significance, allowing animals to
make decisions about how to react to stimuli
• In sum, sensory processing occurs in stages with
neurons responding to more and more complex aspects
of the environment as information is transmitted to higher
brain regions.
Elemental Theories of Perception: Structuralism
• Discussed by Wundt (1832-1920) but mostly developed
by Edward Titchener (1867-1927).
• Theory holds that perceptions are created by combining
or adding up elements of sensations.
• Ex: For vision, visual stimuli are coded in different groups
of neurons that convey this information, in parallel, to
higher brain regions. When neural signals arrive at a new
brain site, the information is recombined and transmitted
to other parts of the brain.
Feature Integration Theory
• The main evidence for structuralism stems from the fact
that the time to process two features (ex: colour and
shape) of a stimulus is the sum of the time it takes to
process the two individually.
• This effect would not be expected if perception was
synergistic.
• Feature Integration theory is a modern version of
structuralism. It posits that elements of sensory input are
coded at the initial stages of processing, and then
combined at higher levels to produce perceptual wholes.
Gestalt Psychology
• Elemental theories of perception seem at odds with
human experience, in which the sensory world is
perceived as “whole”
• Gestalt psychologists proposed instead that individuals
perceive sensory information in its entirety, and then
divide in into elements if further processing is required.
• Founded by Köhler, Wertheimer, and Koffka
Examples of Gestalt Principles
Multistability
Reification
Emergence
Invariance
Top Down vs. Bottom Up
• Gestalt principles are considered “Top Down” processing.
• Structuralism and Feature Integration Theory are
considered “Bottom Up” processing.
Stimulus Filtering
• Both bottom up and top down theories must account for
stimulus filtering…the process of separating and
extracting meaningful information from the many sensory
cues in the environment.
• Ex: Humans can hear a spectrum of sounds, but are
acutely sensitive to those used in speech.
• Stimulus filtering in animals is accomplished by sign
stimuli, the essential features of a stimulus which are
necessary to elicit a specific behavioural response.
Sign Stimuli
• Responses to sign stimuli are typically species-typical
behaviours that occur in a fixed order.
• Ex: Red dot on herring gull bill, red belly on stickleback
males, egg-rolling responses in geese.
• Because they reliably produce species-specific
behaviours that promote survivial, they are sometimes
called releasers.
Attention
• Attention is a mental process that allows us to select
which information will be processed in a world that is full
of both relevant and irrelevant stimuli.
• Attention is difficult to quantify
• tended to be ignored in early S-R learning promoted by behaviourists.
• Nonetheless, many psychologists recognized that
attention likely had important implication for many
cognitive processes, particularly memory.
• With the rise of cognitive psychology, greater interest in attention
occurred.
Human Memory
Reference
(or long-term)
Memory
Declarative Memory
-Facts & Events
Episodic Memory
-autobiographical,
specific event
Semantic Memory
-General world
knowledge
Working
(or short-term)
Memory
Non-Declarative Memory
-Implicit, unconscious
Sensitization
&
Habituation
Procedural
Memory
-Motor Skills
Priming
Classical
Conditioning
Selective Attention
• Selective attention is the ability to attend to a limited range of
sensory information while actively inhibiting competing input.
• A well known example is the “cocktail party effect”
• Eye tracking experiments show adaptive importance of
selective attention—ability to focus on eyes (rather than whole
face) allows one to recognize anger, fear, or friendliness very
quickly.
• Tinbergen (1960) proposed the idea of a search image—a
mental representation of a target formed by foraging animals.
Pietrewics & Kamil (1981)
Sustained Attention
• Sustained Attention allows animals to focus on one aspect of
their surroundings for an extended period of time.
• Measured in both humans and animals using a vigilance task.
• Subjects are required to monitor a particular location and to indicate when a
target stimulus has been presented.
• Both humans and animals show wide variability in sustained
attention.
• Important implications in the wild for vigilance/watching out for
predators (easier for animals in social groups).
Divided Attention
• Divided attention is the ability to process sensory
information from more than one source simultaneously.
• Allows us to do more than one task at once, although
usually one or both tasks will suffer.
• Dukas & Kamil (2000): Blue Jays locate prey better when they can
focus on one target, rather than dividing attention between two targets.
• Feeding guppies are slower to react to predators than resting guppies
(Krause & Godin, 1996)
• Almost all cognitive processes are compromised
when attention is divided between too many sources.
Attention Summarized…
• Selective attention is the ability to attend to a limited
range of sensory information, and is aided by mental
search images.
• Sustained attention is the ability to maintain focus on
one aspect of the environment for an extended period of
time. This aids animals in remaining vigilant in watching
for predators or prey.
• Selective and Sustained attention work in opposition to
divided attention, which allows an animal to process
input from more than one source at a time.
LECTURE :
Sensation/Perception (Part 2);
Memory
Psychology 2210B
Instructor: Krista Macpherson, PhD
Date: January 20th, 2025
Part 1: Sensation
• Evolution of Sensory Systems
• Development of Sensory Systems
• Sensory System Function
Part 2: Perception
• Interpretation
• Measurement (psychophysics!)
• Stimulus Filtering/Attention
• (if we have time…if not next week)
The five senses…
• Vision
• Those other 4?!
• Hearing
• Touch
• Taste
• Smell
• Without these five senses, our brains would not be able to
process anything about our world.
Sensation vs. Perception
• Sensation: The process through which the senses pick
up visual, auditory, and other sensory stimuli and transmit
them to the brain; sensory information that has registered
in the brain but has not been interpreted.
• Perception: The process by which sensory information is
actively organized and interpreted by the brain.
Stimulus Filtering
• Both bottom up and top down theories must account for
stimulus filtering…the process of separating and
extracting meaningful information from the many sensory
cues in the environment.
• Ex: Humans can hear a spectrum of sounds, but are
acutely sensitive to those used in speech.
• Stimulus filtering in animals is accomplished by sign
stimuli, the essential features of a stimulus which are
necessary to elicit a specific behavioural response.
Sign Stimuli
• Responses to sign stimuli are typically species-typical
behaviours that occur in a fixed order.
• Ex: Red dot on herring gull bill, red belly on stickleback
males, egg-rolling responses in geese.
• Because they reliably produce species-specific
behaviours that promote survivial, they are sometimes
called releasers.
Attention
• Attention is a mental process that allows us to select
which information will be processed in a world that is full
of both relevant and irrelevant stimuli.
• Attention is difficult to quantify
• tended to be ignored in early S-R learning promoted by behaviourists.
• Nonetheless, many psychologists recognized that
attention likely had important implication for many
cognitive processes, particularly memory.
• With the rise of cognitive psychology, greater interest in attention
occurred.
Human Memory
Reference
(or long-term)
Memory
Declarative Memory
-Facts & Events
Episodic Memory
-autobiographical,
specific event
Semantic Memory
-General world
knowledge
Working
(or short-term)
Memory
Non-Declarative Memory
-Implicit, unconscious
Sensitization
&
Habituation
Procedural
Memory
-Motor Skills
Priming
Classical
Conditioning
Selective Attention
• Selective attention is the ability to attend to a limited range of
sensory information while actively inhibiting competing input.
• A well known example is the “cocktail party effect”
• Eye tracking experiments show adaptive importance of
selective attention—ability to focus on eyes (rather than whole
face) allows one to recognize anger, fear, or friendliness very
quickly.
• Tinbergen (1960) proposed the idea of a search image—a
mental representation of a target formed by foraging animals.
Pietrewics & Kamil (1981)
Sustained Attention
• Sustained Attention allows animals to focus on one aspect of
their surroundings for an extended period of time.
• Measured in both humans and animals using a vigilance task.
• Subjects are required to monitor a particular location and to indicate when a
target stimulus has been presented.
• Both humans and animals show wide variability in sustained
attention.
• Important implications in the wild for vigilance/watching out for
predators (easier for animals in social groups).
Divided Attention
• Divided attention is the ability to process sensory
information from more than one source simultaneously.
• Allows us to do more than one task at once, although
usually one or both tasks will suffer.
• Dukas & Kamil (2000): Blue Jays locate prey better when they can
focus on one target, rather than dividing attention between two targets.
• Feeding guppies are slower to react to predators than resting guppies
(Krause & Godin, 1996)
• Almost all cognitive processes are compromised
when attention is divided between too many sources.
Attention Summarized…
• Selective attention is the ability to attend to a limited
range of sensory information, and is aided by mental
search images.
• Sustained attention is the ability to maintain focus on
one aspect of the environment for an extended period of
time. This aids animals in remaining vigilant in watching
for predators or prey.
• Selective and Sustained attention work in opposition to
divided attention, which allows an animal to process
input from more than one source at a time.
NEXT UP:
MEMORY
Memory
• The stored representation of past experiences
• More precisely…The mental processes of acquiring
and retaining information for later retrieval
(Ashcraft & Klein, p.9)
• Given this definition, it is difficult to think of any
cognitive process that is independent of memory!
(Human) Memory
Reference Memory
Declarative Memory
-Facts & Events
Working Memory
Non-Declarative Memory
-Implicit, unconscious
Sensitization &
Habituation
Episodic Memory
-autobiographical,
specific event
Semantic Memory
-General world
knowledge
Procedural
Memory
-Motor Skills
Priming
Classical
Conditioning
Memory vs. Other Cognitive
Processes
• Ex: To categorize cats vs. dogs, or different types of
dogs, we first need to remember different types of
animals. Categorization therefore is dependent on
memory.
• The same holds true for other cognitive processes.
• Another important example is Spatial Memory, which is
often studied in non-human animals (typically rats)
using a radial maze.
Radial Maze
Cognitive Maps
• One possibility is that the rats are making a mental list of
the arms they have visited. But rats are good at this task
even when the maze has 16 arms (Cole & ChappellStephenson, 2003), so this seems unlikely.
• More likely that the rats are using a mental “map” or
representation of how the maze is arranged.
• They could then use this cognitive map to navigate the maze
(O’Keefe & Nadel, 1978).
• Beacons, landmarks, and geometric cues are all also
helpful tools which can help an animal navigate within this
map.
Beacon, Landmarks, & Geometric cues
Why did memory evolve?
• Sometimes we make costly mistakes with our memory (ex: eating
wrong food, wandering into wrong territory)…so why did this trait
evolve?
• Answer: Because our world is ever-changing. In a perfectly
stable environment we could operate strictly through S-R
associations. The most adaptive responses would then be
passed on to offspring.
• Difficulty in studying memory across different species…how do
we decide what an animal “should” remember, and how do we
measure it?
• Another approach is to consider the ecology of the animal (ex:
food caching birds).
Inheritance of Memory in
Stickleback Fish
Stages of Memory Processing
• Memory processes involve
three phases:
• 1. Encoding
• 2. Consolidation
• Rehearsal & Retention
• 3. Retrieval
• What we remember and how
well we remember it depends
on all three of these of these
processes.
1. Encoding
• The conversion of incoming information into neural
signals that will be used for later coding.
• Memory depends on us experiencing an event, and
having recorded some memory of that event.
• We do not keep a perfect/literal record of this event,
rather, our experiences are coded in our nervous system.
• Not every piece of sensory info becomes a memory
• Attention plays key role here!
Elaboration
• Enhances encoding
• The process of adding meaning, images, or other complex
information to sensory input.
• The greater the level of processing, the more durable the
encoding.
• Ex: tagging a visual image to a person’s name (Mark = image
of “X” on chest)
• Difficult to know whether this is a uniquely human trait (can’t
ask animals if they do this)
Chunking
One of the criticisms of encoding is that there is a limit on the amount
of information that they nervous system can process.
Miller (1956) suggested that we increase memory capacity by
reducing the amount of information that is encoded through
chunking.
OFDETWHURDSOSKMCNTELPOGSERTUORGETHERORF
LETTERSGROUPEDTOGETHERFORMCHUNKSOFWORDS
Better Encoding Leads to Better
Memory!
• Encoding is not a passive transfer of information.
• It is an active mechanism, and is facilitated by
cognitive processes such as attention, elaboration,
and chunking.
Retrospective & Prospective Coding
So far, we have talked about how animals code information
required to navigate spatially.
We generally think of memory as involving retaining
information about information in the past…but it also
involves planning for the future.
Consider a football quarterback during a huddle. He must
recall the plays that were learned during practice. This
involves retrospective coding.
Executing the play requires the team to remember what
they need to do next in order to complete the play. This
involves prospective coding.
Prospection & Retrospection
Prospection = Imagining the future
Retrospection = Thinking about the past
The cognitive processes involved in thinking about the
past vs. imagining the future seem to be very similar,
which has generated a great deal of interest amongst
cognitive researchers.
Mentally moving back and forth in time is referred to as
mental time travel.
Feeney, Roberts, & Sherry (2011)
Future planning in chickadees.
Experimental Chickadees were given sunflower seeds for 5
minutes, then mealworms (a preferred food) after a delay.
Control Chickadees receive sunflower seeds, but no mealworms.
Question—will the experimental chickadees “save room for
dessert”?
2. Consolidation
The process of modifying encoded representations
so they become more stable over time.
Two components: retention & rehearsal (important in
working memory)
Rehearsal refers to keeping information in an active
state, so that it is readily available for use (ex:
remembering a phone number)
Accuracy of recall can be modified by cues indicated that
something should or should not be remembered
(Johnson, 1994)
Directed Forgetting
• Studies have shown that the accuracy of recall can be
modified by cues indicated that something should or
should not be remembered (Johnson, 1994)
• Directed forgetting occurs when a stimulus (a forget
cue) indicates that working memory will not be tested
on that trial.
Milmine, Wantanabe, & Colombo (2008)
• Pigeons tested in operant
conditioning chamber
with three keys in a row
(Delayed Matching to
Sample Task).
• Middle key displays
sample stimulus (red or
white light)
• Side key used during
memory test (must
peck key that
matches sample
stimulus)
Milmine, Wantanabe, & Colombo (2008)
“I need to study the sample
because there will be a test”
“There is no test, so I don’t
care about studying”
“There’s no test, but
I get food!”
Probe (test f-cue condition)
Probe (test free-reward
condition)
Milmine, Wantanabe, & Colombo (2008)
• In R-cue trials, pigeons remembered the stimulus and matched
correctly in the choice task.
• In F-cue trials, pigeons performed poorly on the choice task (the Fcue disrupted memory).
• Pigeons also did well with the F-r cue…the anticipation of reward
seems to have facilitated memory.
3. Retrieval
• Retrieval occurs when stored information is recovered
so that it can be used to guide behaviour.
• Two mechanisms by which items are retrieved: recognition
and recall.
• Both recognition and recall are better if they occur in
the same context in which the memory was encoded.
• Retrieval processes are triggered by retrieval cues. These
act as reminders…if you are discussing what you did during
reading week last year with your friends, what they say will
trigger other memories of what you did that week.
Memory for Kicking Behaviour in Babies
Borovsky & Rovee-Collier (1990)
• Babies with ribbon
attaching their ankle to a
mobile were trained to kick
in order to move mobile.
• Tested for kicking
response 24 hours later
Forgetting and Sources of Memory Failure
• Failures of memory do not
always reflect the loss of
previously learned
information.
• “Forgetting” is often not the
irreversible loss of
information, but rather some
other mechanism that
interferes with retrieval.
Proactive and Retroactive Interference
The most common sources of memory disruption arise
from exposure to prominent stimuli either before or after
the event you are trying to remember.
Proactive Interference: Occurs when memory is
disrupted by exposure to stimuli before the event to be
remembered.
Retroactive Interference: Occurs when memory is
disrupted by exposure to stimuli following the event to
be remembered.
Proactive Interference (Lewis & Kamil, 2006)
Clark’s nutcrackers were allowed to watch the experimenter
hide a seed in one of 176 cups of sand in a plywood board.
A total of 5 seed hidings were given each day during
training.
Testing for proactive interference involved giving each bird
one of two types of trials on alternate days.
On single list days, the birds watched the experimenter
hide 5 single seeds. Five minutes after the last seed was
hidden, 5 recovery tests were given, one for each seed.
During each recovery test, 6 of the 176 holes were open to
access. Within each cluster of 6 open cups, one cup was the
correct cup while the remaining cups were incorrect. These
were the control trials used to test spatial memory
without proactive interference.
o o o o o o o o o o o
o o o o o o o o o o o
o X o o o o o o o o o
o o o o o o o o o o o
o o o o o o o o o o o
o o o o o o o o o o o
o X o o o o o o o o o
o o o o o o o o o o o
o o o o o o o o o o X
o o o o o o o o o o o
o o o o o o o o o o o
o o o o o o o o o o o
o o o X o o o o o o o
o o o o o o o o o o o
o o o o o o o o o X o
o o o o o o o o o o o
To assess proactive interference, birds were given this task
twice a day…except in these trials the set of correct cups was
different for each set.
For some of the recovery tests for the second list, the 6 cup cluster
did not contain a cup where a seed had been hidden in list 1.
These were control recovery tests to see how the bird performed
when it had received a previous list, but that list did not conflict with
the current recovery test.
For other recovery tests the 6 cup cluster included the correct
cup for the current list, a correct cup from list 1, and 4
incorrect cups.
If proactive interference occurred, it was expected that there would
be more errors on the recovery trials that included a correct
cup from list 1, and those errors would be more likely to occur
to the cup in the cluster that had been correct in list 1. Animals
performed well on two list recovery trials that did not contain an
interfering cup (red cup cluster), but performance was worse on
recovery trials with an interfering cup (green cup cluster) with the
errors most often occurring to the wrong cup from list 1.
o o o o o o o o o o o
o o o o o o o o o o Y
o o X o o o o o o o o
o o o o o o o o o o o
o o o o o o o Y o o o
o o o o o o o o o o o
o X Y o o o o o o o o
o o o o o o o o o o o
o o o o o o o Y o X o
o o o o o o o o o o o
o o o o o o o o o o o
o o o o o o o o o o o
o X o o o o o o o o o
o o o o o o o o o o o
o o o Y o o o X o o o
o o o o o o o o o o o
X = first set of seeds
Y = second set of seeds
Red cluster = no
proactive interference
Green Cluster =
Proactive Interference
from Green X
**Diagram represents
recovery test after
second set of seeds**
Retroactive Interference
• Retroactive interference can be studied using Delayed
matching to sample (DMTS), by presenting a stimulus
during the delay interval before the animal is given
comparison test stimuli.
• Roberts & Grant, 1978: the delay interval between sample and
comparison stimuli normally occurred with no illumination in the
chamber. For the interference manipulation, the chamber was
illuminated during the delay interval.
• If the delay interval was short, there was very little retroactive
interference. If the delay interval was long (longest studied was
12 sec) performance dropped to chance levels.
Roberts & Grant (1978)
Presenting an auditory stimulus
during the delay has a similar
effect, although the retroactive
interference effect is greater
if the interfering stimulus is
in the same modality as the
sample stimulus (ie: light, in
this example).
Retroactive interference is
thought to be due to disruption
of rehearsal of target
information by the subsequently
presented interfering
information.
Reference Memory
• Long-term retention of information necessary for the
successful use of incoming and recently acquired
information.
• Usually involves learning over repeated trials.
• Ex: Remembering what ingredients go in a stew.
Working Memory
• Is operative when information has to be retained only long
enough to complete a particular task, after which the
information is best discarded because it is no longer
needed or because it may interfere with successful
completion of the next task.
• Ex: Remembering which ingredients you have already
added in a recipe for stew.
• All successful working memory requires appropriate
reference memories.
• Like RAM on a computer
How Long can an Animal Remember?
• Skinner (1950) trained pigeons to peck a spot on an illuminated
key for reward.
• The pigeons were tested 4 years later, and immediately began pecking the
key for an extended period of time.
• Rensch (1957) trained an elephant to choose between two
wooden boxes containing different visual patterns, with food
under the correct box. The elephant learned 20 different
versions of this problem.
• A year later, the elephant was tested on 13 of the problems, and was 70-
100% accurate.
• Chaser the border collie (knows the names of 1000+ objects!)
• https://www.youtube.com/watch?v=_6479QAJuz8
Delayed Matching to Sample
• Initially developed to study working memory for
visual cues in pigeons (Blough, 1959).
• “delayed matching to sample is the most frequently
used procedure in the study of nonhuman short-term
remembering” (White, 2013)
• Typically thought of as test of working memory, but
in fact also requires reference memory.
• Has since been adapted to study a number of
different stimuli and species.
Delayed Matching to Sample
• First, subject is presented with a sample stimulus.
This sample stimulus will be the correct response at
the end of the trial.
• Stimulus is then removed for a retention period.
• Subject is then given a memory test with two choices,
one of which is the original sample stimulus.
• Choice of the sample stimulus is reinforced with a
reward.
Delayed Matching to Sample
Roberts (1972b)
Delayed Matching to Sample
• Requires both working and reference memory for
successful completion.
• Working memory helps the subject retain information
about the sample stimulus, until it can be compared to
the test stimulus.
• Reference memory allows the subject to remember the
structure of the task from trial to trial.
• Has been used to study how animals remember
shapes, number of responses performed, presence or
absence of reward, the spatial location of stimuli, and
the order of two successively presented events.
Delayed Matching to Sample
• Not all procedures are equal! Several factors affect
accuracy of recall:
• The nature of the stimuli used
• amount of time subject is exposed to sample
• length of the delay after viewing the sample
• Generally, memory is best the longer the sample stimuli is
presented.
• The longer the delay between the presentation of the
sample stimuli and the choice task, the more mistakes are
made.
Sargisson & White (2001)
• If no delay before “test”,
they can remember stimuli
and match correctly.
• The longer the delay, the
less accurately they
match.
• BUT…the longer they get
to see sample key
(“training time”), the better
they are at matching.
How Many Stimuli should we use?
• If only a few simple stimuli are used, animals don’t
need to “match to sample” to solve the problem—
rather, they could learn a few simple S-R rules to solve
the problem.
• To make sure that animals are not making an
associative response, we need to see if their
performance transfers when tested with new stimuli.
• Oden, Thompson & Premack (1988): Matching to
sample with measuring cup and bolt lock. 80%
accuracy observed when subjects (infant chimps) were
transferred to novel stimuli.
Conclusions
• Memory involves three stages: encoding,
consolidation, and retrieval. What we have talked
about today really only scratches the surface of these
areas of study!
• Memory is an active process, involving continual
updates and modifications.
• Difficulties in any of the three phases of memory can
result in forgetting.
• Experimental paradigms like delayed matching to
sample have helped us greatly in understanding
memory capacity in non-human animals.
(Human) Memory
Reference Memory
Declarative Memory
-Facts & Events
Episodic Memory
-autobiographical,
specific event
-What/Where/When
in non-human
animals
Working Memory
Non-Declarative Memory
-Implicit, unconscious
Sensitization
&
Habituation
Semantic Memory
-General world
knowledge
Procedural
Memory
-Motor Skills
Priming
Classical
Conditioning
Declarative vs. Non-Declarative Memory
• Non-Declarative memory is an umbrella term to describe
types of memory that do not depend on awareness on
explicit knowledge to be expressed.
• Includes Sensitization/Habituation, Perceptual priming,
Classical conditioning, Procedural Memory.
• Declarative memory is a knowledge based system that
is expressed through explicit statements “ex: I remember
when…, I know that…”
• Includes Semantic memory, Episodic memory.
Non-Declarative Memory: Sensitization/Habituation
• Most simple type of non-declarative memory.
• Habituation develops to stimuli with low motivational
significance…allows organisms to filter out irrelevant
information so they do not waste time or energy responding to
a benign stimulus each time it is encountered.
• Sensitization, in contrast, develops to motivationally
significant events (ex: a loud noise, which may be paired with
a shock). Typically studied in animals through startle
responses.
• Both occur in many situations, but always require repeated
exposure to a stimulus.
Habituation
• Very useful as an experimental paradigm in both human
developmental psychology as well as animal cognition
studies.
• Typically compares amount of time subject spends staring
at a familiar versus a novel stimuli.
Turati, Bulf, & Simon (2008)
• Adapted visual attention task to study face perception.
• Newborn infants were familiarized with photos of faces
either full-faced or slightly angled.
Non-Declarative Memory: Perceptual Priming
• The facilitated identification of a stimulus as a
consequence of prior exposure to the stimulus.
• Functions primarily at the unconscious level.
• Birds are better at detecting prey in a visual search task if
item appeared in previous trials (Pietrewicz & Kamil,
1981).
Non-Declarative Memory: Classical Conditioning
• One of the principal categories of associative processes.
• Process by which a previously neutral stimulus, through
pairing with a motivationally significant event, acquires the
ability to elicit a response.
• Ex: Bell paired with food comes to elicit salivation in
Pavlov’s dogs.
• We will discuss this topic in detail next week!
Non-Declarative Memory: Procedural Memory
• A gradual change in behaviour based on feedback.
• We use this when we tie our shoes, comb our hair, or play
a musical instrument.
• Assessed in animals most frequently using operant
conditioning tasks.
• In most cases, performance improves with training (ex:
rats running through mazes or lever pressing).
Declarative Memory: Semantic Memory
• Tulving (1972) was the first to suggest that declarative
memory should be divided into knowledge of facts and
knowledge of episodes.
• Knowledge of facts is known as semantic memory. It
describes general knowledge of the world that is not
tagged to a particular event.
• Includes knowledge of words and their meanings as well
as concepts (ex: gravity)
Declarative Memory: Episodic Memory
• Knowledge of episodes is known as Episodic Memory. It
involves knowledge for events in a personal past.
• This autobiographical information is unique to each
individual as it is associated with a particular time, place,
and event.
• Has been a highly contentious topic in animal cognition!
Recall…Prospection & Retrospection
• Prospection = Imagining the future
• Retrospection = Thinking about the past
• The cognitive processes involved in thinking about the
past vs. imagining the future seem to be very similar,
which has generated a great deal of interest amongst
cognitive researchers.
• Mentally moving back and forth in time is referred to as
mental time travel.
Feeney, Roberts, & Sherry (2011)
• Future planning in chickadees.
• Experimental Chickadees were given sunflower seeds for 5
minutes, then mealworms (a preferred food) after a delay.
• Control Chickadees receive sunflower seeds, but no
mealworms.
• Question—will the experimental chickadees “save room
for dessert”?
Food Caching
• Numerous species store food when it is abundant, and
visit these caches later to recover the stored food.
• Ex: Scrub Jays, Black-capped Chickadees, Clark’s
Nutcrackers.
• Clark’s Nutcrackers, for example, hide seeds in
underground caches and recover them in winter and
spring. They hide as many as 33, 000 seeds in caches of
4-5 seeds each, and recover several thousand.
Food Caching
• Strongly related to ecological factors
• Varies among species and within different populations of
same species (ex: Alaskan black-capped chickadees vs.
Colorado black-capped chickadees).
• Caching behaviour has become a rich source of
information about comparative cognition
• Caching animal must deal with several issues:
• What foods to cache (perishable vs. non-perishable)
• Where to cache food (must be recoverable)
• Social situation (will competitors steal the cache)
How do birds cache/retrieve food?
• Many studies have focused on spatial memory as a
means through which animals retrieve their caches.
• BUT…experiments must rule out alternate possibilities,
such as:
• Randomly searching for caches
• Only hiding food in specific types of caches
• Marking storage sites
• Locating storage locations by smell or sight.
• Many studies have been conducted to rule out these
nonmemory explanations of caching behaviour.
Episodic Memory in Animals?
• The food caching/recovery paradigm has also become
very popular in asking questions about episodic memory
in animals.
• Episodic memories are very rich in detail…they tell us
what, where, and when something happened.
• Also involves a phenomenological component…the
conscious awareness (or autonoetic consciousness)
that an event was in the past and that you are now
remembering it (Tulving, 1983).
Episodic-like memory in animals
• Episodic memory was originally described by Endel Tulving
(1983) and was considered to be a uniquely human trait
(because of the component of awareness).
• Unlikely to be able to determine whether or not non-human
animals have the conscious awareness component of episodic
memory…but we CAN study the what, when and where
components of episodic memory.
• We refer to this “episodic-like” memory. Food
caching/recovery is an ideal way to study episodic-like memory,
as we can easily manipulate the what/where/when components
of memory.
Clayton & Dickenson (1999)
• Varied palatability of food in Western Scrub Jays (peanuts vs.
meal worms)
• Question: Will birds care/remember what is stored where,
based on when they are allowed to retrieve it?
• Birds were allowed to cache both peanuts and meal worms in
ice cube trays.
• This is followed by a retention interval of 4 or 124 hours.
• After 4 hours, both foods are still good…but after 124 hours
worms are decayed!
Clayton & Dickenson (1999)
Clayton & Dickenson (1999)
• Birds learned to recover meal worms after a 4 hour retention interval,
but peanuts after the 124 hour retention interval.
• As a control, a replenish group was used. In this group, fresh worms
were always provided after the 124 retention interval. These birds
always searched for worms as a result!
(Experimental Condition)
(Control Condition)
Summary
• Memory progresses through three phases: encoding,
consolidation, and retrieval.
• In most cases, memory facilitates other cognitive processes.
• Working Memory is the active process of maintaining and
updating information in short-term store.
• Reference memory can be conceptualized within a multiple
memory model, containing both declarative and nondeclarative forms of memory.
• episodic-like memory contentious issue in comparative
cognition.
ASSOCIATIVE LEARNING
Psychology 2210B
Instructor: Krista Macpherson, PhD
Date: Jan 27th, 2025
Midterm
• Feb 3rd @ 1:30pm in class
• Format:
• Multiple Choice
• Fill in the blank
• Short answer
• Can answer point form
• Short Essay (1)
• 2-3 paragraphs
• https://www.youtube.com/watch?v=qG2SwE_6uVM&t=3s
Beyond Habituation and Sensitization…
• For the most part, habituation and sensitization involve
learning just about one stimulus, and bring an organism
“in tune” with its environment.
• Events in the world, however, often do not occur in isolation.
• If humans and non-human animals were limited to these
kinds of behavioural mechanisms, they would be very
limited in the kinds of things they could do.
• Learning what stimuli occur together can help us more
effectively interact with our environment!
Associative Learning
• Two kinds of associative learning have dominated the
psychological literature:
• A. Classical (or “Pavlovian”) Conditioning
• B. Instrumental (or “Operant”) Conditioning.
A. Classical Conditioning
• Also known as Pavlovian conditioning
• Classical conditioning is the most simple mechanism
whereby organisms learn about the relations between one
event and another.
• Classical conditioning enables both humans and non-
human animals to take advantage of orderly sequences in
the world:
• Your car does not run unless the ignition has been turned on.
• You cannot walk through a door until it is opened.
• It does not rain unless there are clouds in the sky.
History of Classical Conditioning
• Most famously associated with Russian Scientist Ivan
Pavlov (1849-1936).
• Simultaneously discovered by Edwin Twitmyer (1873-
1943).
• Twitmyer tested knee-jerk reflexes in college students by
sounding a bell .5 seconds before striking the patellar
tendon just before the knee cap (after several trials, the
bell alone would elicit the knee-jerk response).
Ivan Pavlov
• Not a psychologist.
• His studies of classical
conditioning were an
extension of his original
research in digestion, for
which he won a Nobel
prize.
• Initially maintained a
strong belief in nervism
• As part of his digestive research, Pavlov developed
artificial fistulae that collected stomach secretions
• Lab technicians observed that dogs produced stomach
secretions merely at the sight of food, or even at the sight
of the person who normally fed them.
• The lab assistants referred to these as psychic
secretions, because they appeared to occur at the mere
thought of food.
Pavlov’s Realization
• Pavlov realized that the dogs drooling in mere presence
of food was a simple but important form of learning.
• He began pairing the food with other, neutral stimuli, in
order to study this form of learning.
• The process of acquiring, through experience, new and
relatively enduring information or behaviours.
The Classical Conditioning Paradigm
• Pavlov’s procedure involved two simuli.
• The first was a light or a tone that does not elicit
salivation at the beginning of the experiment (a neutral
stimulus).
• The second was a food (typically meat powder) or the
taste of a sour solution which was placed in the dog’s
mouth. This would elicit vigorous salivation even the first
time it was presented.
The Classical Conditioning Paradigm
The Classical Conditioning Paradigm
• The tone/light is the conditioned stimulus (CS).
• The food/sour taste is the unconditioned stimulus (US).
• The salivation that eventually came to be elicited by the
tone/light is the conditioned response (CR).
• The salivation that was always elicited by the food/sour
taste is the unconditioned response (UR).
The Classical Conditioning Paradigm
• CS: A stimulus that does not elicit a particular response
initially, but comes to do so as a result of becoming
associated with a US.
• US: A stimulus that elicits a particular response without
the necessity of prior training.
• CR: The response that comes to be made to the CS as a
result of classical conditioning.
• UR: A response that occurs to a stimulus without the
necessity of prior training.
Contemporary Studies of Pavlovian Conditioning
• Contemporary studies of Pavlovian conditioning uses
many different species, including humans, rats, mice,
rabbits, pigeons, quail).
• These procedures were developed primarily by North
American scientists during the second half of the
twentieth century.
• Behaviorism dominant school in North America during this time
Fear Conditioning
• Watson & Rayner (1920) believed that infants are at first
limited in their emotional reactivity…interested particularly
in the conditioning of emotion.
• Assumed “there must be some simple method by means
of which the range of stimuli which can call out these
emotions and their compounds is greatly increased”
• The “simple method” they spoke of is Pavlovian
conditioning.
• Conditioned fear response to a white rat in baby Albert.
Little Albert (1920)
Little Albert
• John Watson conditioned Little Albert to fear a rat through
associative conditioning
• Generalized to other white furry objects/animals
• turns out that “Albert” was not healthy, possibly
neurologically impaired and died at age of 6
• Douglas Merritte was thought to be true identity (Fridlund & Beck, 2012)
• Albert Barger, a man who died in 2007 has since been suggested
• Proper debriefing never occurred
• His mother may have been an employee of the hospital
where the research took place, possibility of coercion
"Give me a dozen healthy infants, well-formed, and
my own specified world to bring them up and I'll
guarantee to take any one at random and train him
to become any type of specialist I might select-doctor, lawyer, merchant-chief, and yes, even
beggarman and thief, regardless of his talents,
penchants, tendencies, abilities, vocations, and race
of his ancestors." Watson (1930)
Fear in Non-Human Animals
• Fear and anxiety are sources of considerable human
discomfort, and in severe cases can lead to serious
psychological problems.
• Scientists are currently working to better understand the
neural mechanisms of fear and anxiety, and how these
behaviours are acquired.
• Many of these questions cannot be addressed with
human subjects, for ethical reasons.
Freezing in Rats
• The aversive US in these studies is a controlled shock
delivered through the floor of a cage.
• The CS in these studies is typically a discrete stimulus
(ex: light/tone).
• Rats show fear by freezing. Freezing is a common
defense response that occurs in a variety of species in
anticipation of aversive stimulation.
Freezing in Rats
• Freezing is defined as immobility of the body (except for
breathing) and the absence of movement of the whiskers
associated with sniffing.
• Freezing probably evolved as a defensive behaviour—animals
are less likely to be caught by predators if they are motionless.
• When animals freeze, they stop lever pressing. Number of
lever presses during CS vs. number of presses during non-CS
period is a measure of conditioned fear.
• Suppression Ratio: LP during CS/(LP during CS + LP
during an equal period of time preceding CS)
Conditioned Suppression
0.6
0.5
0.4
0.3
0.2
0.1
Note: y-axis is
incorrect in some
versions of
textbook (p.113)!
Other measures of fear-induced immobility
• Conditioned suppression procedures involve the
suppression of ongoing behaviours.
• Lick-suppression procedure: Ongoing behaviour is
licking a drinking spout. If a fear CS (a tone) is used,
licking behaviour is suppressed, and it will take them
longer to make a specified number of licks.
• Bar-press suppression: Rats can be trained to press a
lever for food reward. Tone or light is then paired with
brief shock. As subjects acquire the conditioned fear, they
suppress lever pressing during the CS.
Sign Tracking
• Pavlov’s research originally dealt with salivation and
highly reflexive responses, which encouraged the belief
that classical conditioning occurs only in reflexive
response systems.
• This restrictive view of Pavlovian conditioning has since
been abandoned. This is because of more complex
paradigms like sign tracking (aka autoshaping).
Sign Tracking
• Animals often approach and contact stimuli that signal the
availability of food.
• Ex: A squirrel can predict the availability of acorns based on the
leaves and shape of oak trees.
• By approaching these contact stimuli, the animal is likely
to be rewarded with food.
• Sign tracking is investigated in the laboratory by
presenting a discrete, localized visual stimulus just
before the delivery of food.
Burns & Domjan (2000)
• “long-box” procedure
• Subjects were male domesticated quail
• CS = wood block lowered from ceiling 30 seconds before a female
quail was introduced.
• CS and female were presented at opposite ends of 8 foot chamber.
• Male quail actually went to the CS, rather than the side where the
female would be presented.
Is Sign Tracking Always Observed in
Pavlovian Conditioning?
• No
• Individual differences in sign tracking have been attributed
to individual differences in impulsivity and vulnerability to
drug use (Tomie, Grimes, & Pohorecky, 2008)
• Greater activation of dopamine reward circuits
• Sign tracking is thus a valuable model for studying
learning processes and neural mechanisms that
contribute to drug addiction.
Sign Tracking vs. Goal Tracking
• Individual differences in sign tracking have been shown in rats.
• Rats placed in chamber with food cup in the middle of the wall.
Lever inserted through slots on either side of the cup.
• Lever = CS, food delivered to cup = US
• For each conditioning trial, lever is inserted/withdrawn, followed
by delivery of food. Rats then tested in trials in which no food
is delivered.
• Sign tracking measured by contact with lever (CS)
• Goal tracking measured by contact with food cup (US)
Flagel, Akil, & Robinson (2009)
Sign Tracking
Goal Tracking
Rats developing
sign tracking as
CR (Black
circles)
Rats using goal
tracking as CR
(White Circles)
(Grey dots are rats using both sign and goal tracking)
Learned Taste Aversions
Monarch vs. Viceroy Butterflies
Learned Taste Aversions
• When we eat, the sight, taste and smell of food are
experienced before the food is swallowed/digested.
• The sensory aspects of food are the CS (ex: wing pattern
in monarch butterfly).
• Exploited by the viceroy, a form of mimicry
• These become associated with the consequences of
eating (good or bad), which are the US.
• Learned taste aversions can occur even if illness
does not occur for several hours.
• Differences amongst species though!
Long-delay Taste Aversion (Smith & Roll, 1967)
• Rats put on water deprivation schedule, so that they are
thirsty.
• Given water flavoured with saccharin, then exposed to
radiation from x-ray machine to induce sickness.
• Control group taken to x-ray, but not irradiated (“sham-
irradiated”).
• Following radiation/sham-irradiation, given choice of
normal or saccharin water to drink for two days.
Percentage of Preference
Preference for Saccharin Solution (Smith & Roll, 1967)
CS-US Interval (hours)
Dietary Generalists vs. Specialists
• Rats forage for multiple
foods and cannot clear
their system of toxins by
vomiting.
• Neophobic, takes only a
small bit of anything new
• If it gets sick, avoids food in
future
• Vampire bats, unlike
insectivorous bats, are
dietary specialists, who
consume blood.
Common vampire bats could not form
learned taste aversions
Common Pavlovian Conditioning Procedures
• to measure the
effectiveness of
conditioning, we can
measure magnitude,
probability or latency of
response.
• no “best” procedure, per se
• when the CS occurs matters,
not just the CS-US relationship
• we can measure magnitude,
probability or latency of
response to determine
effectiveness
Common Pavlovian Conditioning Procedures
• Delayed, simultaneous, trace, and backwards
conditioning all result in strong learning and vigorous
conditioned responding in certain instances.
• Long-delayed conditioning occurs in learned taste
aversions.
• Fear conditioning in CS results in freezing with short-
delayed procedure, but escape with simultaneous
procedure.
• Backwards conditioning produces mixed results.
• Can be inhibitory
Mechanisms of Associative Learning
• 1. Temporal Contiguity
• 2. Stimulus Salience
• 3. Informativeness (Blocking, Latent Inhibition)
• 4. Extinction
1. Temporal Contiguity
• A US that immediately follows a CS and a response that
immediately produces a reinforcer induce robust conditioning.
• Similarly, when there is a long delay before receiving reinforcement,
animals are more likely to make associations with extraneous stimuli
(Dickenson, 1980).
• There are exceptions though
• long delay taste aversion
• Temporal contiguity does not account for all explanations in
associative learning
• “superstition” in pigeons
• Timberlake (1984): When rats are reinforced after 5s, rats develop CR of
gnawing at CS. When reinforcement occurs after more than 5s, foraging CR
was developed.
2. Stimulus Salience
• Animals are much quicker to acquire responses to stimuli
that are salient, and responding is increased when the
stimuli have biological significance to the animal.
3. Informativeness—Latent Inhibition
• Latent Inhibition: Previous exposure to the CS, in the
absence of the US, hampers subsequent conditioning to
the CS.
• Basically…a familiar stimulus takes longer to acquire
meaning as a CS than a new stimulus.
• This is because organism first learns that CS has no
motivational significance…they must then overcome this
information in order to learn the association between the
CS and the US.
The Blocking Effect
• The blocking effect involves interference with the
conditioning of a novel stimulus because of the presence of
a previously conditioned stimulus.
Phase 1: Experimental group received pairing of stimulus A
with US until association is formed (ex: bread pudding CS,
illness US).
Stimulus B is then presented with Stimulus A (ex: bread
pudding with sauce) and paired with US (illness).
***very little responding to stimulus B will happen when
presented on its own, even though it is paired with US***
Blocking Effect
• Bread Pudding = Illness
CS1
US
• Bread Pudding + Sauce = illness
CS1
CS2
• Sauce alone = NO illness
CS2
US
US
So sauce on bread
pudding won’t result
in illness, even
though it was paired
with bread pudding.
Sauce is “blocked”
by previous
association with
pudding.
The Rescorla-Wagner Model
• Is a model of Pavlovian conditioning in which the animal is
theorized to learn from a discrepancy between what is
expected to happen and what actually happens.
• Mathematical model for conditioning in which the
prediction of the US for a trial can be represented as the
sum of all the associative strengths for the CS present
during the trial.
• utilizes notion of the importance of “surprise” in US.
• One of the most influential models of learning
The Rescorla-Wagner Model
• If you expect a new pair of shoes for your birthday and
instead get a car, this would be an unexpectedly large US.
• If you expect a car and get a pair of shoes, this would be
an unexpectedly small US.
• Rescorla & Wagner assumed that the level of surprise
(ie: the effectiveness of the US) depended on how
different the US was from what the subject expected.
• Strong conditioning = strong expectation of US
• Weak conditioning = weak expectation of US
How it works…
• Learning on a given conditioning trial is the change in
associative value of a stimulus, represented by ΔV.
• (λ – V) is the level of surprise (the difference between
what occurs (λ) and what is expected (V)
• k is a constant related to the salience of the CS and US.
• The idea that learning depends on the level of surprise at
the US is therefore expressed as follows:
ΔV = k (λ – V)
The Delta Rule:
• ΔV = k (λ – V)
• This is the fundamental equation of the Rescorla-Wagner
model, sometimes known as the Delta Rule
• The Delta rule indicates that the amount of learning ΔV is
proportional to how far predictions of the US differ from
what actually occurs (λ – V). The prediction error (λ – V)
is very large at first but gradually becomes smaller.
US that is delivered on a given trial.
Level of “surprise”
How does Rescorla-Wagner Explain the Blocking Effect?
• Recall that the first stimulus A in the blocking effect
receives extensive conditioning so that it reliably predicts
the US. In other words, Stimulus A has already reached
the asymptote of learning (λ).
• In Phase 2, Stimulus B is presented together with
Stimulus A, and the two CSs are paired with the US, so
V = VA + VB
• Because of Phase 1 training, VA = (λ) at the start of Phase
2. But VB starts at 0. So V = λ + 0, or λ.
• Therefore, stimulus B takes on no associative value in
Phase 2, which results in the blocking effect.
4. Extinction
• In classical conditioning, extinction involves repeated
presentations of the CS without the US.
• appears to be the reverse of acquisition…but its not!
• We’ll come back to this in a bit!
B. Operant Conditioning
• Operant conditioning, is a method of learning that
occurs through rewards and punishments for behavior. It
encourages the subject to associate desirable or
undesirable outcomes with certain behaviors.
• Also known as Instrumental Conditioning
• Whereas classical conditioning concerns how animals
adjust their behaviour to elements of the environment that
they do NOT control, operant conditioning focuses
explicitly on their goal-directed or instrumental
behaviour
Video:
• https://www.youtube.com/watch?v=H6LEcM0E0io
Early Investigations of Operant Conditioning
• E.L. Thorndike—Puzzle Boxes
• Different boxes require different responses to get out.
Thorndike’s Law of Effect
• States that if a response R in the presence of a stimulus S
is followed by a satisfying event, the association
between the S and the response R becomes
strengthened.
• If, on the other hand, the response if followed by an
annoying event, the S-R association will be weakened.
• ***key feature of this mechanism is that it compels the
organism to make response R whenever stimulus S
occurs. Explains many compulsive behaviours.
• Ex: smell of popcorn (s) entices you to eat popcorn (r)
Watson’s “Behaviourist Manifesto” (1913)
• 1. Psychology should be purely
objective, with any interpretation of
conscious experience being removed,
thus leading to psychology as the
"science of behaviour"
• 2. The goals of psychology should be
to predict and control behaviour (as
opposed to describe and explain
conscious mental states).
• 3. There is no notable distinction
between human and non-human
behaviour.
John B. Watson (1878-1958)
B.F. Skinner (1904-1990)
• led “radical behaviourism”
movement in psychology
• Creator of operant
conditioning chamber (also
known as “Skinner Box”)
• Also, the “air crib”…but no, it
wasn’t a baby prison!
• Considered one of the most
influential psychologists of the
20th century, and the “father”
of operant conditioning.
B.F. Skinner (1904-1990)
Operant Conditioning Chamber
(Skinner Box)
The “Air Crib”
• Random Fact:
Skinner originally
wanted to call it the
”Heir Conditioner”
• NOT a baby prison!
Types of Operant Conditioning
Procedures
• Positive Reinforcement
• Positive Punishment (Or punishment in textbook)
• Negative Reinforcement
• Negative Punishment (Or omission in textbook)
• Often referred to as the “four quadrants” of operant
conditioning.
• Positive = Something added
• Negative = Taking something away
• Reinforcement = increase in behaviour
• Punishment = decrease in behaviour
Four quadrants of operant conditioning…
Modern Approaches to the Study of Operant
Conditioning
• Involve Discrete-Trial Procedures or Free-Operant
Procedures.
• Discrete-Trial Procedures: Similar to Thorndike’s
procedure in that each trial begins with putting animal in
apparatus, and ends when they complete instrumental
response.
• Often involves maze learning.
• Behaviour typically measured using running speed or
latency
Modern Approaches to the Study of Operant
Conditioning
• Free-Operant procedures: allow the animal to repeat the
instrumental response without constraint over and over again,
without being removed from the experimental apparatus until
the experimental session is complete.
• Invented by B.F. Skinner (1938) to study behaviour in a more
continuous manner than is possible with mazes.
• Allows experimenter to observe
variations in responding across
time.
Measuring Operant Behaviour
• Unlike discrete-trial techniques for studying operant
behaviour, free-operant methods permit continuous
observation over long periods of time.
• Therefore the subject, not the experimenter, determines
the frequency of response. This allows us to observe
changes in the likelihood of response over time.
• The relationship between responding and reinforcement is
determined by the reinforcement schedule
Reinforcement Schedules: Ratio
• Reinforcement is based on number of reponses
• Fixed Ratio (FR): A set number of responses is required
to obtain reinforcement.
• Variable Ratio (VR): Number of required responses
varies around a mean value.
• Progressive Ratio (PR): Animal must make increasing
number of responses.
Reinforcement Schedules: Interval
• Reinforcement is based on how much time has elapsed
• Fixed Interval (FI): Time subject must wait before
response can result in reinforcement is the same across
trials.
• Variable Interval (VI): Responding is reinforced after an
average time interval has passed. Like the VR schedules,
the average time required to set up the reinforcer is used
to label so (so if reinforcement occurs at 1min, 3min, and
2min, it will be a VI2).
Comparison of Ratio and Interval Schedules
• While it may seem that interval and ratio schedules
influence behaviour in the same way, they are in fact very
different!
• With both FR and FI schedules, there is a post-reinforcement
pause.
• Both FR and FI schedules result in increased responding right
before delivery of reinforcer.
• In contrast, both VR and VI schedules maintain steady rates of
responding without predictable pauses.
Reynolds (1975)
• Compared the rate of pecking in pigeons on VR and VI
schedules.
VR birds
respond 5
times as
fast as VI
birds!
Reinforcement Schedules
• Animals are also more sensitive to the payoff of a
given scenario.
• Acquisition is more rapid and declines more quickly in
continuous reinforcement than with partial reinforcement.
• Fixed schedules result in rapid responding up to the
presentation of reinforcer (the ratio run), with post
reinforcement pause after delivery of reinforcement.
• Ratio strain: extremely large FR may result in animal
stopping response altogether.
Schedules of Reinforcement
Superstition in Pigeons
• Skinner put pigeons in separate chambers and had food
delivered every 15 seconds regardless of what the bird was
doing.
• Skinner noted that birds would turn counter-clockwise, “toss”
their heads, and make other random movements, even though
they were being reinforced for nothing.
• Skinner thought these behaviours had accidentally been
reinforced and referred to them as “supersititious”
• many researchers felt that temporal contiguity was the main
factor for learning in operant conditioning at the time…these
results from Skinner appeared to support them.
Staddon & Simmelhag (1971)
• Replicated Skinner’s superstition experiment, but made more
systematic/extensive observations.
• Defined a variety of responses, recorded when they occurred
• orienting to food hopper
• pecking response key
• wing flapping
• turning in circles
• preening
• Data showed that clearly, certain behaviours occurred
predominantly at the end of the interval between successive
reinforcers.
• These were labeled terminal responses.
• Others occurred in the middle of the interval between food
deliveries
• These were labeled interim responses.
Staddon & Simmelhag (1971)
R1 = Orienting toward food magazine
(terminal response)
R7 = Orienting towards magazine wall
(terminal response)
R8 = moving along magazine wall
(interim response)
R4 = making quarter turn (interim
response)
R3 = pecking at floor (interim
response)
Staddon & Simmelhag (1971)
• Staddon & Simmelhag’s data suggest that what Skinner
observed weren’t accidental behaviours at all.
• To draw on Behaviour Systems Theory (Timberlake &
Lucas, 1985), the periodic deliveries of food most likely
activate species-typical foraging and feeding responses.
• As time for food approaches, animal will engage in focal search
behaviours.
• Immediately after food is received they engage in post-food focal
search
• in-between, they engage in general search.
Differences Between Operant and Pavlovian
Conditioning
• One of the simplest ways to remember the
differences between classical and operant
conditioning is to focus on whether the behavior is
involuntary or voluntary.
• Classical conditioning involves making an association
between an involuntary response and a stimulus,
while operant conditioning is about making an
association between a voluntary behaviour and a
consequence.
Differences Between Operant and Classical
Conditioning
• In operant conditioning, the learner is also rewarded
with incentives, while classical conditioning involves
no explicit enticements.
• Classical conditioning is passive on the part of the
learner, while operant conditioning requires the
learner to actively participate and perform some type
of action in order to be rewarded or punished.
Extinction
• In classical conditioning, extinction involves repeated
presentations of the CS without the US.
• In operant conditioning, extinction involves no longer
providing reinforcement when the operant response
occurs.
• In both cases, conditioned behaviour will decline until it
disappears. It therefore appears to be the reverse of
acquistion…but its not!
Extinction
• Association is never “erased” or lost, however…a CR will
reappear after extinction if there is a delay. This is known
as spontaneous recovery.
• If a novel stimulus is introduced during extinction, animal
will be distracted and start responding to new stimulus.
This is disinhibition.
• Ex: Dog with salivation CR to bell CS is given extinction training. Bell
then presented with without food, and salivation declines. When bell is
presented with new light stimulus, salivation recovers.
Extinction
• Extinction trials are context specific—if extinction trials are
conducted in a new context, response declines but will reemerge when CS is presented in original context. This is
Response Renewal.
• Renewal typically occurs as follows:
• Acquistion training conducted in presence of contextual cue A
• Participant then moved to context B for extinction training
• When participants are moved back to context A, conditioned
responding returns.
Study Guide: Exam 1
• NOTE: This is NOT and exhaustive list of everything on
the on the exam. Rather, it is meant as a “checklist” to
help guide your studying.
• Lecture 1:
• Major historical figures
• Four Questions of Ethology
• Fixed action patterns
• Different approaches to the study of animal
cognition/behaviour
• Anthropomorphism
• Anecdotal Method
• Morgan’s Cannon
• Clever Hans
• Lecture 2
• Sensory systems
• Sensory System Adaptation
• Sensory Drive Hypothesis
• Sensory System Development
• Compensatory plasticity hypothesis
• Blindsight
• Structure of the eye/retina/photoreceptors
• Fechner’s Law and Weber’s Law
• Absolute Threshold
• Difference Threshold
• Methods of Detection
• Top Down vs. Bottom-Up
• Lecture 3
• Attention
• Selective/sustained/divided
• Cognitive Maps
• Stages of Memory
• Proactive/Retroactive Interference
• Directed Forgetting
• Reference vs. Working Memory
• Delayed Matching to Sample task
• Declarative vs. Non-Declarative Memory
• Non-Declarative
•
•
•
•
Sensitization/habituation
Priming
Procedural memory
Classical Conditioning
• Declarative
• Semantic
• Episodic-like memory
-Clayton & Dickenson (1999)
• Lecture 4:
• Classical Conditioning
• Fear Conditioning/conditioned suppression
• Sign tracking vs. goal tracking
• Learned taste aversion
• Temporal Contiguity
• Latent Inhibition
• Rescorla-Wagner and Blocking Effect
• Operant Conditioning
• Four quadrants
• Free Operant procedure
• Schedules of Reinforcement
• Superstition in Pigeons
• Extinction