Conditioned reflexes and habit formation / by W. Horsley Gantt.

  • W Horsley Gantt
Date:
[1932?]
Catalogue details

Licence: In copyright

Credit: Conditioned reflexes and habit formation / by W. Horsley Gantt. Source: Wellcome Collection.

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    tinguished others are extinguished after a fewer number of trials, and it is so even with those for other receptors. Then, when the conditioned reflexes are restored, extinc¬ tion is much easier than it was the first time. Associative Inhibition The second kind of internal inhibition is associative or conditioned inhibition, which occurs when the indifferent agent is given together with the positive conditioned stimulus and the combination is reinforced. Suppose we have a metronome (M) which we have made into a posi¬ tive conditioned stimulus. Every time we use it we give food. Now we give the metronome plus the light (L) (which has never been used before) ; with this combina¬ tion we do not give food, although each time we give M alone we do feed the animal. At first the animal reacts to the combination of M and L as it does to M alone, but as this stimulus is repeated the salivary secre¬ tion to it gradually diminishes to zero, although M alone gives the same effect as before. L, which was indifferent for the food centre, has now acquired an inhibitory value, not only for the stimulus with which it was used, but for other food stimuli and also for stimuli of other centres. For example, if we now combine L with a bell (B), which is a positive food stimulus, the combination L plus B produces no salivary flow the first time it is used. L, from its association with M, now has a different signi¬ ficance for the animal from what it had before it was used with M. Or even if L is given with a conditioned stimulus —not for food but for the introduction of acid into the mouth—it will inhibit the conditioned reflex to the acid. Thus we come to see that all extraneous and accidental stimuli or changes in the environment coinciding with an inhibitory state of the animal in time acquire the property of themselves calling out this inhibition. Chain Conditioned Reflexes How closely related internal inhibition and excitation and how slight a change in temporal relations constitute the determining factor as to whether the same indifferent agent under otherwise identical conditions becomes posi¬ tive or negative—“ a hair perhaps divides the false from the true,” as the poet has it—are seen in this example. If we combine the positive conditioned stimulus M with some agent L so that M coincides with it and overlaps it, then L becomes an inhibitory signal—a conditioned inhibition. But if L precedes M by a few seconds, then L takes on the character of a positive conditioned