CHAPTER 4

1. CHAPTER 4 Pavlovian Conditioning: Causal Factors

2. NECESSARY CONDITIONS FOR PAVLOVIAN CONDITIONING • Contiguity • For Pavlov, conditioning involved simple, mechanical associations between events that occurred closely together in time. • Contiguity between CS and US automatically stamped in a connection between them.

3. NECESSARY CONDITIONS FOR PAVLOVIAN CONDITIONING • Contingency • But, in 1967, Robert Rescorla suggested that although contiguity between CS and US might be necessary for conditioning to occur, it might not be sufficient. • What might also be necessary is that there be a differential contingency between CS and US. • Only then would CS convey information about occurrence of US.

4. NECESSARY CONDITIONS FOR PAVLOVIAN CONDITIONING • It now appears that information is critical for Pavlovian conditioning. • Does CS provide reliable information as to whether US is forthcoming? • Just when is US likely to occur? • Such information appears to be taken into account in production of CRs.

5. Information and Conditional Probability • Imagine two hats: one large, one small. • Imagine 10 red balls and 10 green balls in large hat. • Imagine 10 blue balls and 10 yellow balls in small hat.

6. Information and Conditional Probability • Without knowing hat size, what is P of picking a red ball from either hat? 10/40 = .25. • If hat is large, then what is P of picking a red ball? 10/20 = .50. • If hat is small, then what is P of picking a red ball? 0/20 = .00. • Clearly, P of picking a red ball depends on hat size. • We thus say that P of picking a red ball is conditional on hat size.

7. Information and Conditional Probability • This analysis suggests that hat size conveys information about ball color. • Information may be critical for conditioning. • If CS provides information about occurrence and timing of US, then organisms should attend to and learn about it. • Such learning might involve: • Positive relations or contingencies • Negative relations or contingencies • Random relations--no contingency whatsoever

8. Information and Conditional Probability • Positive Relation • P(US|CS) > P(US|No CS): Excitation • Negative Relation • P(US|CS) < P(US|No CS): Inhibition • Random Relation • P(US|CS) = P(US|No CS): Learned irrelevance or learned helplessness

9. Information and Conditional Probability • Experimental evidence is consistent with informational theory. • Yet, informational theory is incomplete without considering role of time in conditioning: • CS-US Interval (ISI) • Intertrial Interval (ITI) • ISI/ITI Ratio

10. Informativeness, Redundancy, and Blocking • Organisms may not only be sensitive to whether a CS predicts a US, but whether it better predicts the US than other CSs. • In other words, conditioning may involve the selective association of a US with the most predictive CS. • If two or more CSs predict the US, then each is said to be redundant.

11. Selective Associations • Two prime examples of selective associations: • Overshadowing • Blocking

12. Overshadowing • If a CS is a compound of two stimuli and one is more salient or noticeable than the other, then nearly all of the conditioning occurs to the more salient stimulus--overshadowing. • The less salient one may be completely overshadowed, even though it alone could have been an effective CS.

13. Overshadowing

14. Blocking • An overshadowing effect can occur even if both stimuli are quite salient. • This kind of overshadowing results from organism’s past experience with stimuli. • It further shows selective association based on informativeness of stimuli.

15. Blocking

16. PREDICTIVENESS, FEAR, AND ANXIETY • One hallmark of a successful science is that it yields a technology that can be used to improve human life. • In Pavlovian conditioning, attempts have been made to use Pavlovian principles to explain emotional disorders. • Those attempts have relied on importance of predictiveness to Pavlovian conditioning. • One case is fear versus anxiety.

17. Fear Versus Anxiety • Fear is said to be objective: focused on particular objects or situations. • Anxiety is said to be subjective: unfocused or diffuse. • Anxiety is thought to be main component of many types of psychopathology. • People with anxiety disorders are emotionally paralyzed and unable to identify source of paralysis. • They become withdrawn, unable to act, and miserable.

18. Fear Versus Anxiety • There is much evidence for conditioned fear. • Using shocks as USs and tones or lights as CSs reliably produces fear to light or tone. • Evidence for conditioned anxiety comes from randomly presenting CSs and USs. • This procedure does not produce conditioned fear to tone. • Rats behave no differently in presence of tone than in its absence. • Rats suppress lever pressing at all times. • They also huddle, seemingly frozen with terror.

19. Fear Versus Anxiety • These rats develop stomach ulcers. • These ulcers are not produced by shock itself, but by its unpredictability. • Animals exposed to tone-shock pairings do not develop ulcers. • Key here is that predictable shock means there is a safety signal (no CS). • There is no safety signal with unpredictable shock.

20. PAVLOVIAN CONDITIONING AND INHIBITION • Through pairing of CS and US, CS comes to excite a CR. • But, what happens if--after excitatory conditioning--subject receives presentations of CS without US? • Answer: Extinction and (perhaps) Pavlovian conditioned inhibition.

21. PAVLOVIAN CONDITIONING AND INHIBITION • What is inhibition? • Activesuppression of behavior that would occur under other circumstances. • External inhibition is unconditioned. • Internal inhibition is conditioned.

22. PAVLOVIAN CONDITIONING AND INHIBITION • Study of conditioned inhibition poses special methodological problems. • A sign of conditioned excitation is presence of a response that did not occur before conditioning. • But, a sign of conditioned inhibition is absence of a response that might otherwise occur. • Mere absence of that response does not guarantee that conditioned inhibition is present. • Response could be absent for many other reasons--most obviously lack of excitation.

23. PAVLOVIAN CONDITIONING AND INHIBITION • Methods to observe inhibition: • Disinhibition • Summation • Resistance to reinforcement • Retardation • Approach-withdrawal

24. Disinhibition • According to Pavlov, presentation of a novel stimulus will inhibit inhibition. • Suppose that salivation to CS has been extinguished and that extinction produces inhibition. • CS is presented and dog does not salivate. • If novel stimulus is given with CS, then dog will resume salivating.

25. Summation

26. Resistance to Reinforcement

27. Retardation

28. Approach-Withdrawal • CS+  Food • CS-  No Food • Animals approach CS+ • Animals avoid CS-

29. CONDITIONS PRODUCING INHIBITION • Extinction • Conditioned Inhibition Training • Negative Contingency Training • Inhibition of Delay • Discrimination and Generalization • Excitatory and inhibitory gradients • Backward Conditioning

30. NECESSARY CONDITIONS FOR INHIBITION • Inhibitory stimulus must signal absence of otherwise expected US. • It is not sufficient to present a cue in absence of a US for inhibition to develop. • In fact, nonreinforced pre-exposure of CS retards its ability to become a conditioned excitatory stimulus and it reduces its ability to become a conditioned inhibitor--latent inhibition of excitation and inhibition.

31. Pavlovian Conditioning: Causal Factors • Contiguity and contingency play strong roles in Pavlovian conditioning. • Stimuli seem to compete with one another for control of Pavlovian CRs. • Excitation and inhibition both seem to regulate Pavlovian CRs. • Explanations of Pavlovian conditioning must take these findings into account.