“ . . . Ss were required . . . to guess whether a right or left light would go on, indicating their guesses by pressing a lever below the appropriate light. Trials . . . [involved] non-shock . . ‥ [and] an immediate shock (IS) every time he pressed one lever and a randomly delayed shock (RDS) every time he pressed the other lever, irrespective of whether he guessed correctly or incorrectly.” Results: a significant avoidance of the lever leading to RDS, a significantly greater number of Ss judged the RDS as more unpleasant than IS, a marked impairment of Ss' recall of stimulus events and their behavior during the shock trials. (PsycINFO Database Record (c) 2006 APA, all rights reserved)