PSY402 Theories of Learning. Chapter 9 Biological Influences on Learning

Transcription

1 PSY402 Theories of Learning Chapter 9 Biological Influences on Learning

2 Limits to Learning How general are the laws of learning? Skinner s rules work in both lab and real-world settings, across species. Learning doesn t explain all aspects of behavior. Organization of behavior already exists within an organism. Learning modifies that organization.

3 Behavior Systems Approach Timberlake learning changes the integration, tuning, instigation or linkages within a behavior system. Different cues are salient to different behavior modes. Variations in learning occur across species because their behavior systems are different. Variations in behavior are the result of predispositions and constraints.

4 Components of Rat Feeding System

5 Animal Misbehavior Breland & Breland trained 38 species of animals for Busch Gardens. Elicitation of foraging and food-handling instincts interferes with performance of operant routines. Instinctive drift Pig and piggy bank Raccoons and food-washing

6 Pig Misbehavior

7 Explaining Misbehavior Does misbehavior result from operant food reinforcement or classical conditioning? Timberlake s appetitive structure view both kinds of learning contribute to animal misbehavior. Pairings with food are necessary but not sufficient to evoke misbehavior. Children play with their food if allowed.

8 Schedule-Induced Behavior Superstitious behavior induced by FI schedules. (see videos on next slide) The animal associates whatever it is doing at the time with the reinforcement. Ritualistic, stereotyped behavior during the interval. Two kinds of behavior: Terminal reinforcer-oriented Interim follows reinforcement.

9 Superstitious Behavior Examples wscgw superstitious pigeons BCk dog training example

10 Schedule-Induced Polydipsia Polydipsia drinking too much water. Occurs with a fixed interval (FI) schedule. Rats are deprived of food then trained to bar press for food. Rats consumed excessive amounts of water even though not water deprived. May be an example of interim behavior does not occur right before reinforcement.

11 Other Schedule-Induced Behaviors Excessive wheel running highest post reinforcement and during interim. Attack targets of aggressive behavior. Pigeons attack a stuffed model of another pigeon. Similar behavior in squirrel monkeys and rats. Animals continue to drink a flavor paired with illness. Polydipsia is immune to flavor aversion learning.

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13 Intervals Produce More Polydipsia SIP groups got periodic reinforcement PD groups got one big meal

14 Effects with Humans Schedule-induced behavior may be a good animal model for alcoholism: Use of an interval schedule is one of the few ways of inducing rats to drink ethanol. More beer drinking with FI-90 schedule in game playing with humans. Weaker in humans Develops rapidly, stops quickly

15 Flavor-Aversion Learning Long-delay learning does not depend on contiguity. Can precede illness by hours. Preparedness certain stimuli are innately more likely to be associated with a UCS than others. Visual cues more salient to birds Taste cues more salient to rats Salience depends on when the animals seeks its food (nocturnal or not).

16 Salience of Cues for Rats

17 Explanations Learned-Safety theory an evolved mechanism unique to flavor-aversion to protect animal. Ingestional neophobia small quantities consumed at first. Eat again if no illness occurs. Concurrent-Interference view long delay occurs because the animal doesn t eat anything else for a while. Supported too.

18 Support for Learned Safety View Time & repetition led to learned safety for longer delay groups

19 Applications Cancer chemotherapy (UCS) causing nausea may be associated with hospital food (CS). Preexposure to food without the toxic drug or drug without food may help prevent food aversions. Coyotes and wolves can be taught to avoid attacking and eating sheep using flavoraversion learning.

20 Flavor Preference Learning Two reasons for acquired flavor preference: Sweetness preference a non-sweet flavor is associated with sweetness. Flavor-nutrient preference flavor is associated with positive nutritional consequences Young rats prefer glucose to sucrose because they cannot digest sucrose as well. Humans prefer high fat cream cheese despite bitter Dopamine receptors activated

21 Imprinting Lorenz social attachment process where young ducks follow their mother. Ducks imprint to: Moving objects with lifelike motion Vocalizing objects, short rhythmic sounds, not high-pitched Objects that are the right size Occurs within 1 to 6 hours after hatching

22 Goslings Imprinted on Lorenz

23 Infant Love Harlow baby primates attach to soft terry cloth rather than wire. Rocking rather than stationary Warm rather than cold Ainsworth attachment to a responsive mother. Occurs more easily during sensitive period of animal s life. 6 to 12 months for humans

24 Sexual Preference Imprinting In birds, occurs early in development, long before sexual maturity, not modifiable later. Not dependent on reinforcement Birds can sexually imprint on another species, such as a human.

25 Nature of Imprinting Both instinctive and associative processes are involved. Associative-learning view objects become familiar before fear system matures Familiar objects reduce fear later, so become preferred due to relief. Harlow s studies contradict this. Some objects are more imprintable (cloth versus wire mother).

26 Monkeys Prefer Cloth Mother

27 Instinctive View of Imprinting Organisms contain an innate schema of the imprinting object Evoluntary pressure to learn the right thing. Response is hard to change. Extinction does not lead to loss of preference for the imprinted object. Abused primates and children cling to abusive mothers despite punishment.

28 Avoidance of Aversive Events Species-specific defense reactions (SSDR) instinctive responses to specific dangers. Rats running, freezing, fighting. Cues predicting danger also select the specific response. Escape and avoidance behaviors are learned more readily when they incorporate SSDRs.

29 Better Learning for SSDR SSDR

30 Reinforcement Area of Brain Some people are intensely motivated to obtain reinforcement; others lack interest in it. Brain systems may be involved in response to reinforcement. Electrical brain stimulation (ESB) was used to study this. Olds & Milner discovered rats would press a bar for stimulation of the hypothalamus.

31 Sample Cumulative Record

32 Two Reinforcement Pathways Motivation Memory

33 Rat Reinforcement System

34 Motivation-Reward Center Medial forebrain bundle (MFB) in the limbic system is the brain s reinforcement center. Has both reward and motivating properties. Motivation is stimulus-bound (behavior depends on what reward is available). Presence of reinforcement enhances MFB functioning, increasing response to reinforcers. Deprivation arouses MFB.

35 Memory-Learning Center In addition to the MFB, a separate pathway facilitates storage of experiences. Nigrostriatal pathway consolidates memory. The other pathway (tegmentostriatal) is governed by dopamine. Drugs like amphetamine and cocaine activate dopamine receptors. Natural reinforcers (water, food) also increase dopamine.

36 Opiates Have Their Own Receptors Opiates do not activate dopamine but their own opiate-sensitive receptors in the VTA. Two kinds of receptors exist, one for dopamine another for opiates. High responding in the NA leads to compulsive behavior, including gambling, hypersexuality, buying, restless leg syndrome. Parkinsons treatment may cause high responding

37 Both Activate the NA