Acquisition of a second-order classically conditioned response.

Following alleyway food-training on a 50% random partial reinforcement schedule and 10 forward 1st-order (CS1-UCS) conditioning trials elsewhere, forward 2nd-order (CS2-CS1) classical conditioning trials were initiated for 40 female albino rats (Group 1) and equivalent but backward (CS1-CS2) training was started for 20 additional Ss (Group 2). After each set of 2 CS1-UCS and 3 CS2-CS1 trials (or 3 CS1-CS2 trials for Group 2) were given, the CS2 was presented in the goal area of the alley on nonreinforced trials to assess its suppressing effect on total running times. While the performance of Group 2 to the CS2 was unchanged as a function of conditioning trials, Group 1 evinced both increasing suppression and skin conductance levels as 2nd-order training progressed. Maximum suppression was obtained by the 12th CS2-CS1 trial. (French summary) (16 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)