PSY402 Theories of Learning

1. PSY402Theories of Learning Friday February 28, 2003

2. Criticisms of Two-Factory Theory • Avoidance behavior is extremely resistant to extinction. • Should extinguish with exposure to CS without UCS, but does not. • Levis & Boyd found that animals do not get sufficient exposure duration because their behavior prevents it. • Avoidance persists if long latency cues exist closer to the aversive event.

3. Is Fear Really Present? • When avoidance behavior is well-learned the animals don’t seem to be afraid. • An avoidance CS does not suppress operant responding (no fear). • However, this could mean that the animal’s hunger is stronger than the fear. • Strong fear (drive strength) is not needed if habit strength is large.

4. Avoidance without a CS • Sidman avoidance task – an avoidance response delays an aversive event for a period of time. • There is no external cue to when the aversive event will occur – just duration. Temporal conditioning. • How do animals learn to avoid shock without any external cues for the classical conditioning of fear?

5. Kamin’s Findings • Avoidance of the UCS, not just termination of the CS (and the fear) matters in avoidance learning. • Four conditions: • Response ends CS and prevents UCS. • Reponse ends CS but doesn’t stop UCS. • Response prevents UCS but CS stays. • CS and UCS, response does nothing (control condition).

6. D’Amato’s Acquired Motive View • D’Amato proposed that both pain and relief motivate avoidance. • Anticipatory pain & relief responses. • Shock elicits unconditioned pain response RP and stimulus SP motivates escape. • Classically conditioned cues sP elicit anticipatory pain response rP that motivates escape from the CS.

7. Anticipatory Relief Response • Termination of the UCS produces an unconditioned relief response RR with stimulus consequences SR. • Conditioned cues elicit an anticipatory relief response rR with stimulus consequences sR. • Example: dog bite elicits pain response, sight of dog elicits anticipatory pain, house elicits relief

8. A Discriminative Cue is Needed • During trace conditioning no cue is present when UCS occurs and no avoidance learning occurs. • A second cue presented during avoidance behavior slowly acquires rR-sR conditioning. • Similarly, in a Sidman task, cues predict relief -- associated with avoidance behavior, not the UCS.

9. How is rG Measured? • Anticipatory goal responses were initially measured as peripheral nervous system (ANS) response. • No consistent relationship between such measures and behavior could be found. • Now, Rescorla & Solomon propose that these anticipatory states are due to CNS activity (brain states).

10. Guthrie’s Contiguity Theory • Guthrie rejected the necessity of reward. • Contiguity is enough to establish an S-R association. • A response that occurs when a stimulus is present will automatically become associated with it. • Learning is entirely governed by co-occurrences – contiguity in time.

11. Impact of Reward • According to Guthrie, reward is important, but it does not strengthen the S-R association. • The effect of reward is to change the stimulus context present prior to reward. • New actions are conditioned to this revised stimulus context. • Reward prevents further conditioning of the undesired behavior.

12. Guthrie’s View of Punishment • Punishment is a stimulus that can either be escaped or avoided. • If a response terminates punishment, it will replace the punished behavior next time that context occurs. • Punishment works only if the response elicited by the punishment is incompatible with the punished behavior.

13. Importance of Practice • According to Guthrie, learning occurs in a single trial. • The strength of the S-R bond does not slowly increase with experience. • Performance increases because subjects must learn which stimuli are consistently present. • Over time, many different stimuli become associated with a response.

14. Criticisms of Contiguity Theory • Guthrie conducted few studies to support his theory. • Accurate parts: • Punishment can intensify inappropriate behavior when it elicits a response compatible with the punished response. • Contiguity is essential to prevent conditioning of competing associations. • Not all environmental cues are noticed.

15. Impact of Reward • Guthrie’s view of reward has been disproved. • If what happens after a response is not rewarding, an S-R association is not formed, even if the stimulus changes. • Noble – reward size predicts response better than recency or frequency (contiguity measures).

16. Single-Trial Learning • All-or-nothing (single-trial) learning has been difficult to demonstrate. • Voeks – found single-trial learning of an eye-blink response in humans. • Other studies report gradual learning. • Spence proposed a threshold explanation of single-trial learning using incremental learning theory.

17. Skinner • Emphasized the importance of environment (reinforcers & contingencies). • Validation of hypothetical constructs interferes with analysis of the variables controlling behavior. • Anti-theory