PSY 402

1. PSY 402 Theories of Learning Chapter 10 – A Synthetic Perspective on Instrumental Learning

2. Avoidance Learning • Avoidance learning is puzzling because the reinforcer is not obvious. • What sustains running to the other side in a shuttlebox? • How can something that does not happen be a reinforcer? • Mowrer’s two-factor theory was the first explanation.

3. Two-Factor Theory • The first factor is Pavlovian fear conditioning. • A light is a CS that warns of a shock. • The CR is fear. • The second factor is reinforcement of avoidance behavior. • The avoidance response terminates the fear (CR) and the experience of relief (negative reinforcer) rewards the behavior.

4. Acquired Drive Experiment • Miller presented a shock in the presence of a white chamber. • Later, rats could exit from the white side to a black side through a door. • Later rats had to run in a wheel to open the door to the black side. • Later rats had to press a lever to open the door to the black side. • The later responses were reinforced by relief.

5. Clinical Applications • Drug-taking and alcohol use may be reinforced by escape from negative affect. • People with panic disorders such as agoraphobia avoid the places that evoke anxiety. • OCD hand-washing reduces fear of contamination. • Bulimic purging reduces fear of getting fat.

6. Problems with Two-Factor Theory • The strength of the avoidance response should be correlated with the strength of the fear, but it is not. • Dogs avoiding shock don’t look worried. • Maybe after extensive training, habit takes over. • Learning that turns off the CS but not the shock should reinforce behavior, but doesn’t unless it is related to an innate behavior. • Learning varies with the type of response.

7. Species Specific Defense Reactions • An avoidance behavior is easy to learn in the lab if it is similar to a SSDR. • Thigmotaxis – wall-seeking behavior. • Rats learn to jump to a platform along the wall but not in the middle of the space. • Mice from Eastern vs Western Washington freeze in response to different predators. • Neither freeze to garter snakes or squirrels.

8. Freezing is a CR (Respondent) • Rats rapidly learn to freeze in order to avoid shock, but the behavior is a CR not operant. • 100% of rats learned to freeze to avoid shock. • Rats punished for freezing never learned not to freeze. • Freezing was elicited by the punishment – the box became a CS eliciting the freezing as CR. • Pavlovian learning is important to avoidance.

9. Endorphins • CS’s associated with shock also elicit endorphins (natural pain killers). • These inhibit recuperative behaviors (licking a wound) that would interfere with evading a predator. • The actual SSDR elicited depends on the situation as well as the species (flight, freezing, burying). • Fear also inhibits pain.

10. CS Termination is Important • Animals are able to learn non-SSDR behaviors under certain circumstances. • Termination of the CS aids such learning because it provides feedback about the correct behavior for avoidance. • Feedback stimuli become conditioned inhibitors. • The avoidance response becomes an inhibitor too. • Not performing the response predicts the US.

11. Expectancies About Shock • Seligman & Johnston proposed that an expectancy is formed that response=no shock. • This idea is inconsistent with learning theory. • DeHouwer found that changing an expectancy to response=shock (when no signal is present) does not change the avoidance behavior. • The idea that avoidance behavior is a negative occasion setter (response-no shock) fits better.

12. Learned Helplessness • Overmeier & Selgman found that dogs have difficulty learning avoidance behavior after being exposed to inescapable shock. • Step 1 – expose dogs to 3 conditions: escapable shock, inescapable shock (yoke), no shock • Step 2 – escape training • Results – yoked dogs did not learn to escape.