CHAPTER 4 Pavlovian Conditioning: Causal Factors

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.

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.

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.

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.

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.

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

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

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

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.

Selective Associations Two prime examples of selective associations: –Overshadowing –Blocking

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.

Overshadowing Training Test Strong Test Weak Group SW SW+High RespLow Resp Group S S+High Resp -- Group W W+ --Med Resp

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.

Blocking Phase 1 Phase 2 Test X Group B A+ AX+ Low Resp Group C -- AX+High Resp

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.

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.

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.

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.

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.

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

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.

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

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.

Summation Phase 1Phase 2Testing Control Group Light Alone Tone  Food T (High) T+L (High) Inhibition Group Light and Food Unpaired Tone  Food T (High) T+L (Low)

Resistance to Reinforcement Phase 1Phase 2 Control Group Light Alone T+L  Food (Fast learning) Inhibition Group Light and Food Unpaired T+L  Food (Slow learning)

Retardation Phase 1Phase 2 Control Group Light Alone L  Food (Fast learning) Inhibition Group Light and Food Unpaired L  Food (Slow learning)

Approach-Withdrawal CS+  Food CS-  No Food Animals approach CS+ Animals avoid CS-

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

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.

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.