Response strength to a compound conditioned stimulus and its elements as a function of the element interstimulus interval.

Abstract

Cats were conditioned to a CS composed of a light and a tone. One element preceded the shock US by 550 msec; the other by 700, 1050, or 1250 msec. The response was the GSR. Extinction trials were given to the compound and to each element. The magnitude of response to the compound was the same at all intervals, but response magnitude to the elements was a parabolic function of the long-short interstimulus interval value, with the long and short curves being mirror images of each other, the long being high at 1050 msec. The data are interpreted in terms of different mechanisms functioning at the 1050 msec, interval than at the other 2.