PSY402 Theories of Learning

1. PSY402Theories of Learning Wednesday March 12, 2003

2. Problems with Rescorla-Wagner • Overshadowing – salient cues have more associative strength. • Sometimes a salient cue potentiates another cue instead of overshadowing. • Garcia says cues are indexed. • R-W says cues are seen as unitary stimulus. • Unclear which explanation is correct.

3. More Problems • CS preexposure effect – appearance of CS without UCS prior to learning weakens learning. • Shouldn’t have any effect according to Rescorla-Wagner theory, but it does. • Cue-deflation effect – extinction of a more salient cue enhances learning for the less salient cue. • Should be no change according to R-W.

4. Comparator Theory • If two CS’s are associated, extinction of one should reduce responding to the other. • Sometimes true, other times not. • CS-UCS associations exist for many stimuli but are exhibited only for the strongest. • CS’s are judged in relation to each other.

5. Attentional View • Mackintosh – learned irrelevance occurs during preexposure of CS. • Animals exposed to a novel stimulus exhibit an orienting response. • No orienting with preexposure. • Habituation results in failure of conditioning. • Pairing of CS/UCS in novel context results in learning.

6. Retrospective Processing • Most theories assume the level of responding will be constant after learning. • Baker & Mercier suggest association can change after learning. • Retrospective processing – CS-UCS contingency reevaluated after learning. • Backward blocking – support for theory • Suggests animals have mental representations, memory for events.

7. Operant Conditioning • Nature of reinforcement: • Premack’s probability differential theory • Response deprivation theory • Behavioral economics: • Behavioral allocation – blisspoint • Choice behavior – Herrnstein’s matching law. • Momentary maximization theory • Delay-reduction theory

8. Probability-Differential Theory • Premack – a reinforcer can be any activity that is more likely to occur than the reinforced behavior. • Manipulators vs eaters • High probability behaviors can be used as reinforcers of low probability behaviors. • Frequency of the reinforcer decreases when it is made contingent on another response.

9. Response Deprivation Theory • Timberlake & Allison – deprivation occurs when an activity is used as a reinforcer and is not freely emitted. • The activity is reinforcing because it satisfies the deprivation created. • The animal tries to return to its pre-deprivation level of responding. • Activities can be reinforcing even if their baselines were not higher.

10. Behavioral Allocation • Blisspoint (paired basepoint) – the free operant level of two responses. • Unrestricted responding with two choices of behaviors. • Blisspoint is used to figure out how much behavior an animal will engage in to obtain a reward. • Animals try to get as close to the blisspoint as possible.

11. Problems with Contingencies • Blisspoint is established by looking at behavior before a contingency is established. • The established contingency must take blisspoint into account or it may not increase desired behavior.

12. Choice Behavior • Herrnstein’s matching law – describes how animals act when they have two or more choices. • Different responses have different schedules of reinforcement. • Responding to each choice is proportionate to the reinforcement for each choice – after learning. • This can be expressed mathematically.

13. Delayed Gratification • Why does anyone choose a smaller reward part of the time? • Animals and people typically choose a small immediate reward over a larger delayed reward. • Large rewards are selected when: • The choice is made in advance of reward. • Reinforcers are not visible or reward is already present (pleasurable activity).

14. Complexities of the Matching Law • Maximizing law – sometimes the aim is to obtain as many rewards as possible. • Explains FR-10 vs FR-40 schedules. • Doesn’t work for VI vs VR schedules. • Momentary maximization theory – choose best alternative at the time. • Delay reduction theory – choose what will get the reward the fastest.