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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 ~. +. +. +. R. Withdrawal reflex. 2 categories of learning.

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Nonassociative Learning

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  1. NonassociativeLearning Lecture 3

  2. Reflexes • Inherited behaviors • via genes • Smallest unit of organized behavior • sensory receptors • neurons • effectors • Learning • modification of existing behavior • initially reflexive behavior ~

  3. + + + R Withdrawal reflex

  4. 2 categories of learning • Similar characteristics • Nonassociative • modification of reflexes (unconditional responses) • Habituation • Sensitization • Associative • Respondent learning • Operant learning~

  5. Nonassociative Learning: Habituation • Living near the train tracks • Habituation • ¯response to repeated stimulus • stimulus specific • Ignore biologically unimportant stimuli • Universal in animal kingdom • evolved early • protozoans ~

  6. Adaptiveness of Habituation • Conserves resources • energy • attention • Stimuli w/o consequences • response diminishes ~

  7. Stickleback Fish • Males defend territory • Attack when others approach • If other males do not enter territory • Attack response diminishes ~

  8. Habituation Phenomena

  9. Gradually Decremental Hi Startle Response Lo Number of Presentations

  10. Spontaneous Recovery • Learning is relatively permanent • Reinstatement of reflexive response • due only to passage of time • stimulus may again have consequences ~

  11. Spontaneous Recovery Stimulus Hi Startle Response Time Passes Lo Number of Presentations

  12. Is it fatigue? • Temporary physiological change • Motor? • Sensory? • Dishabituation • introduce extraneous stimulus • recovery of habituated response ~

  13. Dishabituation: Example • Tone (Noise)  startle response in rat • Repeat tone  habituation • Flash a light • Present tone  startle response ~

  14. Dishabituation *Light (New)+ Noise Hi Startle Response Lo Number of Presentations Habituation occurs

  15. Dishabituation • Decrease in response not due to fatigue • animal capable of response • signals a new situation • Response is inhibited • by activity of neurons ~

  16. Generalization • Organism reacts to similar stimuli in the same way • Greater the difference... • less habituation evident • Color perception in infants ~

  17. Effect of Stimulus Intensity • Stimulus intensity • Intense  stronger response • Weak  weaker response • Which stimulus will the organism habituate to more quickly? ~

  18. Strong stimulus Weak Stimulus Stimulus Intensity Hi Startle Response Lo Number of Presentations • If stimulus too strong  no habituation • Biologically important ~

  19. Sensitization • Increased responsiveness • Following a noxious stimulus • Less stimulus specific than habituation • general increase in vigilance • sensitized responses to wide range of stimuli • Adaptiveness ~

  20. Sensitization Noise Shock Hi Startle Response Lo Number of Presentations

  21. Duration:Habituation & Sensitization • Can be short term • lasts hours • Change in neural activity • or long term • several weeks • change in neural structure ~

  22. 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. ~

  23. 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 ~

  24. 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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