ASSOCIATIVE PROPERTIES OF A CONDITIONED INHIBITOR AS A FUNCTION OF AGE IN KITTENS

The efficacy of conditioned inhibition in a novel conditioned stimulus /conditioned inhibitor (CS/CI) compound was tested in 6-, 10-, and 14- week-old kittens. The conditioned response was suppression of respirat ion elicited by a 5.1-sec CS paired with a brief, mild footshock. Duri ng original inhibitory training, a CI was presented 2 sec after the on set of the CS, and the stimuli coterminated 3 sec later without the sh ock. As previously reported, the CI trained in this paradigm is more p otent in older kittens but passes a summation test in all age groups ( Dess & Soltysik, 1989). In the transfer test, the order of the CS and CI was reversed, so that the CI preceded the CS with no stimulus overl ap. Transfer of inhibition to this new compound was virtually absent i n the 6-week-old kittens and nearly perfect in the 14-week-old kittens . The CI alone (before CS onset) elicited a strong fear response in th e youngest kittens, moderate fear in the 10-week-old group, and very l ittle fear in the oldest group. The transferability of inhibitory trai ning to a different temporal configuration of the CS and CI is absent at 6 weeks of age and fully developed 8 weeks later.