Download Nonassociative Learning

Nonassociative
Learning
Lecture 3
Reflexes
Inherited behaviors
 via genes
 Smallest unit of organized behavior
 sensory receptors
 neurons
 effectors
 Learning
 modification of existing behavior
 initially reflexive behavior ~
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Withdrawal reflex
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R
2 categories of learning
Similar characteristics
 Nonassociative
 modification of reflexes
(unconditional responses)
 Habituation
 Sensitization
 Associative
 Respondent learning
 Operant learning ~
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Nonassociative Learning: Habituation
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Living near the train tracks
Habituation
  response to repeated stimulus
 stimulus specific
Ignore biologically unimportant stimuli
Universal in animal kingdom
 evolved early
protozoans
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Adaptiveness of Habituation
Conserves resources
 energy
 attention
 Stimuli w/o consequences
 response diminishes ~
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Stickleback Fish
Males defend territory
 Attack when others
approach
 If other males do not
enter territory
 Attack response
diminishes ~
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Habituation Phenomena
Gradually Decremental
Hi
Startle
Response
Lo
Number of Presentations
Spontaneous Recovery
Learning is relatively permanent
 Reinstatement of reflexive response
 due only to passage of time
 stimulus may again have
consequences ~
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Spontaneous Recovery
Hi
Startle
Response
Stimulus
Time
Passes
Lo
Number of Presentations
Is it fatigue?
Temporary physiological change
 Motor?
 Sensory?
 Dishabituation
 introduce extraneous stimulus
 recovery of habituated response ~
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Dishabituation: Example
Tone (Noise)  startle response in rat
 Repeat tone  habituation
 Flash a light
 Present tone  startle response ~
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Dishabituation
Hi
Habituation
occurs
*Light (New)
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Noise
Startle
Response
Lo
Number of Presentations
Dishabituation
Decrease in response not due to fatigue
 animal capable of response
 signals a new situation
 Response is inhibited
 by activity of neurons ~
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Generalization
Organism reacts to similar stimuli in
the same way
 Greater the difference...
 less habituation evident
 Color perception in infants ~
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Effect of Stimulus Intensity
Stimulus intensity
 Intense  stronger response
 Weak  weaker response
 Which stimulus will the organism
habituate to more quickly? ~
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Stimulus Intensity
Hi
Strong stimulus
Startle
Response
Weak Stimulus
Lo
Number of Presentations
stimulus too strong  no habituation
•Biologically important ~
If
Sensitization
Increased responsiveness
 Following a noxious stimulus
 Less stimulus specific than
habituation
 general increase in vigilance
 sensitized responses to wide range
of stimuli
 Adaptiveness ~
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Sensitization
Noise
Hi
Shock
Startle
Response
Lo
Number of Presentations
Duration:Habituation & Sensitization
Can be short term
 lasts hours
 Change in neural activity
 or long term
 several weeks
 change in neural structure ~
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Habituation & Eating
1st taste most pleasant
  # tastes   pleasantness
 Role in meal termination
 e.g., popcorn, cashews
 Not just for taste
 also texture, shape, odor, etc. ~
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Habituation & Eating: Rats
Cabanac (1971)
 Steady flow of sucrose into mouth
 tasty  disinterest  aversion
 Allow rats to eat all rat chow they want
 voluntarily stop
 offer sucrose: eat just as many calories ~
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Habituation & Eating: Humans
Rolls (1990)
 Preference ratings for foods
 given meal of one of foods
 rated again   rating for just-eaten
food
 Given 2 meals
 different foods   same amount
eaten
 same food  2nd meal ate less ~
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