Classical Conditioning

Underlying Processes and Practical Application

S-S versus S-R Learning

Why does CC occur?

S-S versus S-R Theories

UCS UCR

NS/CS

CR

Pavlov

Pavlov’s stimulus substitution theory:

Theory: The CS becomes a substitute for the UCS.

3 problems: 1. Size of the CR and UCR may differ

2. Not all components of the UCR become the CR ( if the stimulus is food, the CR only elicits salivation. The UCR also entails chewing and swallowing etc.)

3. CR is sometimes in opposite direction of UCR (conditioned compensatory response)

What would you predict?

Addiction brought to America 1000s of American soldiers addicted? Spread to rest of population?

This did not happen. Soldier return to normal life. What happened?

Drug Tolerance as…a Conditioned Response:

1st heroin use (1 unit) - euphoria

Anytime with repeated use…. 2 units “10” 3 units “10” so, you need more

of the drug to achieve the same effect.

Compensatory Responses

Decrease in the effectiveness of a drug with repeated use is called tolerance.

Why does tolerance occur? 1. Physiological changes: metabolism is altered. 2. Due to classical conditioning

Compensatory Responses

Seigel (1975) : drug tolerances due to contextual stimuli that regularly precede a drug administration.

The room in which the drug is administered (CR) has the effect of an increased sensitivity to pain.

The result effect is that the CR + UCR cancel each other out

More drug is required

Compensatory Responses When the room changes, the former

CSs are removed, thus the compensatory reaction is also removed

Heroin (5 units, with room change…) physiological overload

OD, coma, and perhaps results in death

Compensatory Responses

CR

UCRUCS

Friends, Place, Smells, behaviors prior to use

Compensatory responses Treatment…

Exposure to cues, initially causes craving

Without UCS, cravings decrease

By Santoro, Deletis, Bergman

Rescorla-Wagner Model

Mathematical model of classical conditioning, on a trial by trial basis

The key is the relationship between

1) expectation 2) strength of UCS

6 Rules of RWM

1. If 2> 1 it is excitatory conditioning

2. If 2< 1 it is inhibitory conditioning

3. If 1=2 no conditioning occurs

6 Rules of RWM 4. Greater discrepancies result in

greater conditioning

5. Salient conditioned stimuli condition faster than subtle conditioned stimuli

6. If two or more conditioned stimuli are presented together, the expectation is that CS1 + CS2

RWM Consider: A light becomes a CS for food (UCS). On

the first trial, the subject has no expectation of food, therefore the strength of the UCS is greater than the expectation, which results in excitatory conditioning (consists of rules 1 and 4.)

Blocking: same expectations as above, but the tone is added after a number of conditioning trials.

no conditioning occurs because there is no surprise the strength of the subject’s expectations matches

the strength of the UCS. (rule 3)

RWM Extinction and Conditioned Inhibition:

same expectations as above, and a tone is added after a number of trials, but no food is delivered. (extinction trial).

this time, expectation exceeds the UCS strength (1>2), which is consistent with rule 2.

RWM

Overshadowing: If a strong CS is paired with a weak

CS, when presented in a compound form, the strong CS will overshadow (condition faster) than the weak CS.

Consistent with rule 5 (more salient stimuli will condition faster)

Rescorla Wagner Model: (formula)

this model predicts the outcome of classical conditioning on a trial by trial basis.

Total/change in learning = TCL

TCL= salience of CS x (UCS strength - expectation)

A product of past learningis constant

RWM

Let’s suppose….

Trial 1 TCL = ? (we have to calculate) Salience = .5 Strength of UCS = 100

1. Vn = 0.5 x (100-0) = 50 2. Vn = 0.5 x (100-50) = 25 50 +25 = 75 3. Vn = 0.5 x (100-75) = 12.5 4. Vn = 0.5 x (100-87.5) = 6.25