Lecture 23: Animal Cognition II
(Special Topics)
Learning, Psychology 3510
Fall, 2015
Professor Delamater
Selected Special Topics in the Study of
Comparative Cognition
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Episodic memory in non-human animals
Interval Timing
Serial Order learning
Categorization and Concept Learning
Episodic Memory: Food Caching Birds
1. Kamil and Balda (1985) study
2. Clayton and Dickinson (1999) study
Kamil and Balda (1985) study
• Clark’s nutcrackers live in Alpine regions of the western US.
• They are known for their uncanny ability to retrieve cached
food in the wild. They store seeds from pine cones during the
summer and fall, and then retrieve them in the winter and
spring.
• They can store up to 33,000 seeds and recover several
thousand of them at some later time.
• Can they do this because they remember well, or because they
can spot markings of where they’ve been? Or just randomly
run into food they’ve or others have previously stored?
Episodic Memory: Food Caching Birds
1. Kamil and Balda (1985) study
2. Clayton and Dickinson (1999) study
• Kamil and Balda forced the birds to store up to 18 seeds in a laboratory environment
with 225 storage holes. However, only 18 were available at any given time.
• Then, after some delay period, they were allowed to retrieve their stored caches.
• But, during this retrieval test, all 225 storage holes were accessible.
• The birds could recover their caches 2-4 times greater than would be expected by
chance.
• Furthermore, they could remember these after as long as a 285 day delay.
Episodic Memory: Food Caching Birds
1. Kamil and Balda (1985) study – This study shows an amazing memory ability.
2. Clayton and Dickinson (1999) study – This study shows some evidence for episodic
memory in birds (Scrub Jays).
What is “episodic” memory? Is it uniquely human?
a. Usual answer is that it is a recollection of a particular event that took place
in a particular location at a particular time. In essence, you reexperience the
episode.
b. Aside from the conscious aspects of this memory, it can be characterized
As a memory containing “what,” “where,” and “when” information.
c. Clayton and Dickinson (1999) asked if scrub jays had this kind of memory.
Episodic Memory: Food Caching Birds
Clayton and Dickinson (1999) study
• Birds were asked to cache different types of food (peanuts and mealworms) into ice
cube trays that had sand in them and were surrounded by lego block structures.
• Then they were asked to retrieve them after 4 or 124 hour delays.
• Some birds learned, though, that the meal worms deteriorated after 124 hours,
whereas for others the bad mealworms were replenished with fresh ones.
Episodic Memory: Food Caching Birds
Clayton and Dickinson (1999) study
• Since the jays preferred mealworms to peanuts, the Replenish group always retrieved
more mealworms (W) than peanuts (P) during the 4 and 124 hour tests.
• The birds that learned that mealworms decay after 124 hours preferred the peanuts to
the mealworms after 124 hours, but worms to peanuts after 4 hours.
• This means that the birds knew after 124 hours what food was stored where and when
it was stored there.
• This suggests that the scrub jays, like humans, may have episodic memories.
Interval Timing: Methods & Properties
1. Duration Estimation (symbolic matching to sample task….)
Sample Stimulus
Tone
Tone
Choice
Choose Response 1 if short
Choose Response 2 if long
• In the duration estimation task, the subject judges whether the first stimulus (the
sample stimulus) is short or long.
• If it is short, then choosing the left response is reinforced with food, but if it is long,
then choosing the right response is reinforced with food.
Interval Timing: Methods & Properties
1. Duration Estimation (symbolic matching to sample task….)
2. Peak Procedure (duration production)
S
S
Response
Reward
Training trials
Fixed Interval 20 s
Response
Nonreinforced Probe trials
80-s S duration
• In the peak procedure, a stimulus comes on and signals reward opportunity after a
fixed interval (e.g., FI 20 s).
• But on nonreinforced probe trials, the duration of the trial is extended and no reward
can be earned.
• It is on these trials that we assess responding as a function of time.
Interval Timing: Methods & Properties
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1. Duration Estimation (symbolic matching to sample task….)
2. Peak Procedure (duration production)
Roberts (1981) study
In this case one discriminative stimulus
signaled FI 20 reward, while a second
signaled FI 40.
The rats lever press rate on probe trials
peaked at 20 and 40 s, respectively, in
the presence of the two stimuli.
This indicates that they have learned
about reward time.
Also, not that the variability (spread) of
the two timing functions differ.
The amount of variation increases with
the mean of the interval being
estimated.
In fact, responding is related to the proportion of time elapsed, independent of the value
of the interval being judged. This is known as the scalar invariance property of interval
timing.
Interval Timing: Theories
1. Scalar Expectancy Theory (Gibbon & Church, 1984)
2. Behavioral Theory of Time (Killeen & Fetterman, 1993)
3. Multiple Oscillator Theory (Church & Broadbent, 1990)
• There are clock, memory, and decision
processes in the scalar expectancy
model.
• Clock generates counts in an
accumulator.
• Memory: Running count vs reinforced
memory count (at time of reward).
• Decision: Compares running value of
elapsed time in working memory to the
stored reinforced time in reference
memory.
• Comparator rule shows how behavior
will be proportionally related to the
value of the reinforced time in
reference memory.
Gibbon and Church, 1984
Comparator:
(N* - N) < b (threshold)
N*
Interval Timing: Theories
1. Scalar Expectancy Theory (Gibbon & Church, 1984)
2. Behavioral Theory of Time (Killeen & Fetterman, 1993)
3. Multiple Oscillator Theory (Church & Broadbent, 1990)
Church and Broadbent, 1990
• In the Multiple Oscillator theory, there
are different oscillators that run
concurrently.
• Each oscillator has a different
periodicity.
• Each moment in time has a different
pattern of activation across the
different oscillators.
• These different patterns of activation
are thought to code different temporal
intervals.
Time 1
Time 2
Serial Order Learning
1. Learn a sequence of responses: 123 234 345 456 567 678 (Fountain, et al, 2012)
2. Do the rats learn an internal representation of the sequence or do they learn
a chain of S-R associations?
• They learn a structured sequence better than a non-structured one.
• But that could be understood in terms of easier associative learning….
Serial Order Learning
1. Learn a sequence of responses: 123 234 345 456 567 678 (Fountain, et al, 2012)
2. Do the rats learn an internal representation of the sequence or do they learn
a chain of S-R associations?
3. Terrace, Son, and Brannon (2003) study
• Monkeys first learned 4, 7-item sequences:
A1 – A2 – A3 – A4 – A5 – A6 – A7
B1 – B2 – B3 – B4 – B5 – B6 – B7
C1 – C2 – C3 – C4 – C5 – C6 – C7
D1 – D2 – D3 – D4 – D5 – D6 – D7
• These stimuli were different pictures taken from several different categories.
• Then the monkeys were given a set of 2-item probe tests consisting of different
stimuli from the different sets. They asked whether the monkeys could
accurately select the first item.
A3 – C5, B2 – D4, C5 – D7, D3 – A4, etc
• The monkeys DID choose the “earlier” item of each sequence even though these
particular items were never trained together.
• It looks like the monkeys had constructed a representation of the order of each
sequence, and this order guided their choices, not a series of S-R associations.
Categorization & Concept Learning
1. Classic Herrnstein, Loveland, and Cable (1976) study
• Pigeons learn to categorize pictures of people vs plants.
• A control group is trained to arbitrarily categorize different sets of stimuli.
• The individual stimuli chosen for this study are taken from a large number of items
(somewhere on the order of 100 or more).
• Then, during a test phase the animals are tested with NEW exemplars (ones they
never saw before), and were asked to choose to respond.
• The birds learning the Categorization task did so fairly well, with some loss in
accuracy.
• Later work has shown that greater generalization occurs in these tests as the
number of exemplars in the training set increases.
Categorization & Concept Learning
1. Grainger, et al (2012) study with baboons
• Baboons first learned to categorize English words
vs non-words (up to over 300 exemplars of each)
• Then they were tested with new words and nonwords they hadnt seen before.
• They’re performance was pretty good, as can be
seen on the graph to the right.
Categorization & Concept Learning:
Mechanisms of Concept Learning
1. Aust and Huber (2003) study with pigeons
• The birds first learned to classify pictures
of people vs no people
• Then they were tested with new exemplars
of people that were in their original
form or were rearranged in various
ways.
• The birds responded most when the new
people were in their original form, but
they responded more to rearranged
people than to slides with no people in them.
• This suggests that the birds responded at least partly on the basis of the
specific features making up the original slides.
• This is the Feature Theory of Concept learning.
• Notice how this is rather similar to the Rescorla-Wagner theory of simple
conditioning.
Categorization & Concept Learning:
Mechanisms of Concept Learning
2. Wright and Katz (2007) study with pigeons, rhesus monkeys, capuchin monkeys
• This was a Same/Different concept learning task
• Do these species learn “abstract” concepts?
• If the two objects on a trial are the same, then
touching the lower picture is correct.
• If the two objects are different, then touching the
button to the right of the lower picture is
correct.
• After the basic learning phase, then the animals
are given tests with new exemplars.
• The basic findings are that generalization to new exemplars increases as the
number of training exemplars increases.
• This result occurs in all species suggesting that all species may learn in
similar ways.
• Perhaps they are abstracting some general notion of sameness, and
responding on the basis of this representation. Further work is needed to
clarify the nature of that representation.