Simultaneous contrast effects in a classical aversive conditioning situation with rats

Abstract

Simultaneous contrast effects by aversive events were assessed in classical contextual conditioning with rats. The degree of freezing response induced by exposure to either the 0.7-or 4.9-s footshock was taken as a measure of conditioned response to the context. The 0.7- and 4.9-s shock were presented for Groups S and L, respectively, in either black or white context. Groups SL and LS received both shocks in alternating days with being correlated with each color of the contexts. The only difference between Groups SL and LS was that Group SL received the 0.7-s shock on the odd days, while Group LS on the even days. Groups S and L served as the controls for the simultaneous contrast effects. Group SL freezed much more than Group L on Day 16, whereas Group LS on Days 14 freezed less than Group S. These results suggests that (1)Simultaneous positive and negative contrast effects were obtained in classical aversive conditioning, (2)rats could compare different durations of shock across different contexts.