PSY402 Theories of Learning

1. PSY402Theories of Learning Monday February 10, 2003

2. Partial Reinforcement Effect (PRE) • Extinction is slowest when behavior was intermittently reinforced during learning. • With humans, the lower the slot machine payoff, the longer people play (resistance to extinction). • But, if the percent of reinforced trials is too low, rapid extinction occurs (U-shaped relationship).

3. Explanations for PRE • Two explanations: • Amsel – frustration-based • Capaldi – sequential theory • Both provide good explanations for observed data.

4. Amsel’s Frustration Theory • Frustration leads to rapid extinction during continuous reinforcement. • During intermittent reinforcement, frustration becomes associated with responding. • Frustration then elicits not suppresses responding.

5. Capaldi’s Sequential Theory • If reward follows a nonrewarded trial, memory of the nonrewarded trial is associated with responding. • During continuous reinforcement, animals do not associate lack of reward with responding. • When they encounter the first nonrewarded trial, the state it produces is not associated with responding.

6. Contingency Management • Assessment phase – determine the frequency of behavior and the situations in which it occurs. • Contracting phase – specifies the relationship between responding and reinforcement. • Management phase – implement the contract and evaluate results.

7. Aversive Conditioning Chapter 5

8. Aversive Events • Unpleasant, undesirable, bad for survival. • Typically evoke strong negative emotion: • Pain, fear, embarrassment or shame, anxiety, frustration. • Strong emotions motivate escape and avoidance behaviors.

9. Escape Conditioning • Escape response – behavior motivated by an aversive event. • Rewarded by termination of the aversive event. • Miller’s shuttlebox – rats escape shock by turning a wheel that opens a door so they can escape.

10. Factors Affecting Escape • Intensity of the aversive event – the stronger the aversive event the greater the escape response. • Amount of negative reward – escape depends on receiving relief from the aversive event. • Reward must be prompt – delayed reward interferes with escape learning.

11. Eliminating an Escape Response • Removal of negative reward – escape response stops if the aversive event continues despite it. • Removal of aversive event -- escape response stops if the aversive event no longer occurs. • Continues for a while due to conditioned anticipatory pain responses. This must be extinguished.

12. Vicious-Circle Behavior • Why did rats run into a pathway with shock when staying still would mean no shock? • Two explanations: • Fear motivates running and is conditioned to the start box. • The animals do not realize that no shock will occur if they don’t run.

13. Avoidance • Active avoidance response – an action is necessary to avoid aversive event. • Passive avoidance response – not responding prevents aversive event. • Mowrer’s hurdle jumping paradigm. • CS causes animal to jump to other side to avoid onset of shock.

14. Effects of Event Intensity • Except in two-way avoidance learning, a stronger aversive event leads to faster avoidance learning. • The greater the aversive event intensity, the faster the passive avoidance learning. • Greater delay between CS and UCS interferes with avoidance learning.

15. One-Way vs Two-Way Avoidance • One-way – animal can avoid shock by jumping to other side. • Two-way – animal can jump to other side, but after a rest, it must jump back again to avoid shock. • Animal avoids shock only by returning to the place where it was first shocked. • The animal must ignore situational cues. • Induces a conflict.

16. Flooding • Avoidance behaviors perpetuate phobias. • Techniques for eliminating avoidance are important to treating phobias. • Flooding forces a person to experience the conditioned feared stimulus without an aversive consequence.