Abstract
In connection with a study of the association areas of the cerebral hemispheres which are essential for obtaining correct conditioned differential responses of a foreleg with olfactory, auditory, general cutaneous and optic stimuli, a correct absence of response appeared in some of the early negative tests with normal and operated dogs, which at first was confused with a later well-differentiated negative conditioned reflex.
Clarification of this reflex requires familiarity with the technic used in the general problem!, as follows: Flexion of the foreleg is the conditioned response, to be correctly positive it must occur within 7 seconds, to be correctly negative it must be withheld for 7 to 15 seconds, depending on the time of appearance of the positive reflex. To be called correct, conditioned differential responses required at least 95% correctness when the positive and negative stimuli were given in varied order. A positive or negative conditioned reflex was never reinforced except for error, in which case the positive error was punished by electric shock and the negative by whipping. Emphasis therefore was placed on the correctness of the reflexes rather than on fine discriminations between analysers.
Two sets of correct conditioned differential tests were used for each sense, one based on components and the other on rate. For example in one set of auditory tests the positive conditioned stimulus consisted of tapping a bell once per second and the negative consisted of tapping a board once per second. In the other set, a bell was tapped once per second for the positive stimulus and 3 times per second for the negative stimulus.
A correct negative reflex that could be elicited by external inhibition 1 is illustrated by the following example, which is but one from many normal dogs in which the first negative conditioned test resulted in absence of response to an auditory, olfactory, or general cutaneous stimulus.
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