A comparator view of theovertraining effect

Gonzalo P. Urcelay & Ralph. R. Miller.

SUNY-Binghamton

Is there a relationship between amount of training and conditioned performance?

• Although counterintuitive, a diminution in conditioned responding is sometimes observed when reinforced training is continued after the CS-US association has reached a peak level.

Kamin, 1961, Exp 1

Extended comparator simulation

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Rescorla-Wagner simulation

The Original Comparator Hypothesis

Clicks Directly Activated US Representation

Conditioning context

ResponseComparison

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Indirectly Activated USRepresentation

Explanations of the overtraining effect

• US habituation

• Inhibition of delay

• Decreased performance due to conditioning of the training context (comparator stimulus)

Objectives

• To demonstrate the basic overtraining effect (Experiment 1)

• To contrast these divergent explanations of the overtraining effect (Experiment 2)

Method

• Conditioned lick suppression with thirsty rats as subjects.

• US = footshock; X = click train• Dependent variable: latency to resume

drinking in the presence of the test stimulus.

Experiment 1. Design

Group Training Test Expected

5 5XUS X CR

10 10XUS X CR

20 20XUS X Cr

50 50XUS X cr

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)Experiment 1. Results

Conclusions from Exp 1

• Other factors being equal, increasing the number of XUS pairings decreased conditioned responding to X.

• We observed an overtraining effect.

Experiment 2

Test divergent explanations of the overtraining effect

Group Training Extinction Test Expected

5C 5XUS CTX 20m X Cr

5E 5XUS CTX 10h X CR

50C 50XUS CTX 20m X cr

50E 50XUS CTX 10h X CR

The Original Comparator Hypothesis

ClicksDirectly Activated US

Representation

Conditioning context

ResponseComparison

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Link 2

Indirectly Activated USRepresentation

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Beginning of context extinction

Experiment 2. Results

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Control Extinction

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Conclusions from Exp 2

• Similar to Experiment 1, without any posttraining manipulation we observed an overtraining effect (Condition Control)

• When the training context was massively extinguished, conditioned responding increased after 5 (not significantly) and 50 training trials

• As indicated by the interaction, the increase was much larger in groups trained with 50 trials.

Overall conclusions• With the present parameters, we saw a

diminution in conditioned responding after extended reinforced training

• When the training context was extinguished, responding after 50 trials recovered, suggesting that this is a performance effect rather than habituation to the US.

Questions?