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