CS familiarization and conditioned suppression in weanling and adult albino rats

Abstract

Twenty-three 30- and 90-day-old rats either were given 60 nondifferentially reinforced presentations of the to-be-conditional stimulus prior to fear conditioning or remained undisturbed. Following pretraining Ss experienced a series of three CS-US pairings. Subsequently, when Ss were tested for suppression of an ongoing licking response to the CS, 23-day-old Ss displayed less suppression to the CS than did adults. In addition, Ss exposed to the CS prior to conditioning demonstrated less suppression in its presence than did nonexposed Ss. It was suggested that weanlings do not demonstrate the decremental acquisition of a CER characteristic of the “latent inhibition” phenomenon seen in older rats. © 1973, The Psychonomic Society, Inc.. All rights reserved.