Chapter 2: Elicited behavior, Habituation, and sensitization
• Elicited Behavior
– behavior is a reaction to a stimulus in the
environment.
• Food  salivation
• Bright light pupil dilation.
• The simplest form of elicited behavior is the reflex.
• Components of a Reflex Arc
• All reflex arcs have five essential components
– 1. receptor
• reacts to a stimulus.
– 2. The sensory (afferent) neuron
• conducts message to CNS
– 3. The integration center
• consists of one or more synapses in the CNS.
– 4. The motor (efferent) neuron
• conducts from CNS to an effector.
– 5. The effector,
• muscle fibers or glands,
– contracts or secretes.
• The reflex arc just described = simplest
situation.
– Often other neural connections are involved.
• Notice that the Reflex arc does not require
any willful conscious act
– Thus - elicited
• Reflexes appear to have evolved to protect the well
being of the organism.
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withdrawal from pain
eyeblink
pupillary reflex
Sneeze, cough, vomit
patellar reflex
rooting reflex.
salivation
release of digestive fluids.
• Animals with reflexive tendencies had an advantage
• Ethology and Modal Action Patterns
– Ethologists study the role of behavior within
the context of species-specific behaviors.
• This is in contrast to the general processes
approach used by most psychologists
• Ethologists
– behavior is generally instinctive.
– often study animals in the wild rather than the
laboratory
• Consummatory behaviors
– behaviors that are crucial for survival.
• feeding, courting, reproducing, and care for offspring.
– innate, genetically determined survival behaviors.
• For Example
– Imprinting.
• Konrad Lorenz
• Why do geese imprint, but other
birds/animals (robins) do not?
– Precocial vs Altricial?
• Ethologists try to find the variables that are
responsible for eliciting the behavior.
– imprinting = two important factors.
• 1. The object must be moving
• doesn’t matter if it is living or not
– ultra lights
• 2. The imprinting must occur within a critical period
• (13-16 hours after hatching).
• Critical Period for learning some things for humans?
– language
• Modal Action Patterns. (MAP’s)
– modern Ethology abandoned the term instinct
• MAPs vs Reflexes
– MAPs are
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more complex
consist of a long series of reflex-like acts
more variable, though still stereotypic
less likely to be evident at or soon after birth.
• In addition, to qualify as a MAP, a behavioral
sequence must meet four specific criteria
according to Moltz (1963)
– 1. Stereotyped
• occurs the same way each time
– 2. continue to completion once begun
• difficult to disrupt
– 3. latent period
• once completed, some time must pass before behavior
appears again
– 4. innate
• the animal must perform the full integrated behavioral
sequence the first time its elicited
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Like Reflexes MAPs are highly adaptive
Protection from predators
– Cat – arch back, fluff hair, hiss
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Protection against the elements
– Migration
– hibernation
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getting food
– Pigs rooting
– spider webs
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courtship and mating
– Big Horn Sheep
– Ducks
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care for young
– Birds
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Nests
Gathering food
– Wasps that capture spiders
• Modal Action Patterns are released by a
sign stimulus
– Sign stimulus
• a specific environmental event that triggers an MAP
– Female pheromones often trigger mating behavior in males
• The sign stimulus works like a key to unlock
an innate releasing mechanism
– innate releasing mechanism
• a neural mechanism that is stimulated by a sign
stimulus.
• controls the modal action pattern
• Examples
– Geese with Eggs
• Rolling away?
• What if it slips on way back?
– stereotyped
• Larger eggs?
– Supernormal stimuli
– Birds feeding young
• Cowbirds
– Herring gull studies
• Which beak works best?
• Do humans exhibit Modal Action Patterns?
– sleep?
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Stereotyped?
continue to completion once begun?
latent period?
Innate?
– emotions?
– sex?
• Effects of Repeated Stimulation
– Descartes thought that a reflexive response
would occur the same way each time it was
elicited
– However – elicited behavior are not invariant
• Habituation.
– repeated exposure to a stimulus reduces
responding to that stimulus.
• Habituation is a very simple form of
learning
• Very useful tool for understanding animal
and infant behavior.
• Can you distinguish between “ba” and “pa”
– Infants?
– Used suck rate as response
• Pacifier with an embedded switch
• As simple as habituation is, it can be used to
tell us a lot about a nonverbal organism
• Other race effect
– Caucasian infants (3.5 months old)
– Group 1 (Caucasian faces)
• shown a Caucasian face until habituated
– Group2 (Asian faces)
• Shown an Asian face until habituated
– Test
• Both groups shown novel faces
– New Caucasian face for group 1
– New Asian face for group 2
Other-race effect in Caucasian infants
• HOWEVER,
• Repetitive stimulation does not always cause
habituation.
– sometimes you get sensitization.
• My father and motorcycle
– emotional response
• flee
– do not habituate
– likely to be more responsive to other stimuli.
• tap on the shoulder
• drop a wrench.
• My dog and car AC
• Davis (1974)
– sensitization and habituation to the same stimulus.
– 110 db noise = loud.
• Gp1 = rats housed in a quiet chamber = 60 db
• Gp 2 = rats housed in a loud chamber = 80 db
• One of the groups decreased their startle response to the 110
db noise after repeated presentations.
• The other group increased their startle response to the 110 db
noise after repeated presentations.
– Which group is which?
– What phenomenon does each group demonstrate?
• What determines whether we get
habituation or sensitization?
– Dual process theory
• Two simultaneous processes
– S-R system
• Reflex arc
– State system
• Involves additional parts of the nervous system
that regulate levels of arousal
• The S-R system and State system are
additive – but in opposite directions
– The more active system will determine
whether habituation or sensitization is
displayed
• Example
– Checkerboard study in book.
– Infants shown checkerboards
• 4x4
• 12 x 12
• Habituation versus Sensory Adaptation
and Response Fatigue
• Sensory Adaptation
– Bright light – blinded
– Loud noise – can’t hear
• Response Fatigue
– Too tired to move
• Stimulus specificity
– Habituation is stimulus specific
• Stop responding to one thing, but if there is a change in
the stimulus the habituation goes away.
– Dishabituation
– Sensitization is not stimulus specific
• If working in a loud factory you may be more reactive to
other stimuli
– Tap on the shoulder
– This is consistent with dual process theory
• S-R system = specific to sensory input
• State system = general arousal
• Time course for habituation
– Short-term = seconds to minutes
– Long-term = may persist for many days
– Leaton (1976)
• Startle response in rats to loud high pitched tone