Rats were trained to turn a wheel to avoid shock. For the 1st group a buzzer was sounded for 5 sec., followed by shock, and both ended simultaneously; the 2nd group was a pseudoconditioning control, for which buzzer and shock were never paired. Both groups were subdivided into high and low shock levels. With high shock there were no significant differences between the groups; with low shock the pseudoconditioning group had a higher percentage of avoidance than the normally conditioned group. "It was concluded that (a) the performance of all Ss is . . . due to pseudoconditioning and (b) random presentation of shock without a warning signal leads to increased sensitization." From Psyc Abstracts 36:02:2EK54S. (PsycINFO Database Record (c) 2006 APA, all rights reserved)