Used 3 levels of shock intensity (1, 2, or 3 ma.), 3 test delay periods (0, 5, or 25 days), and 25- and 100-day-old male Long-Evans hooded rats (N = 104) in a study of developmental differences in recovery from the suppressive effects of punishment. The apparatus was a Y maze with 3 discriminably different arms. After 10-14 sessions of positive reinforcement, Ss were shocked for 2 sessions each time they responded in 1 arm. Following these shock sessions, a delay was given prior to the recovery sessions. Results from the shock days indicate that the number of shocks to suppression was a function of age, intensity, and shock days. The recovery data showed that (a) recovery was an inverse function of intensity, (b) the suppressive effects of punishment were much greater for the adults than the infants at all intensities, and (c) recovery was not a function of delay periods. Results support the hypothesis that younger organisms have greater difficulty than older ones in inhibiting a response. (PsycINFO Database Record (c) 2006 APA, all rights reserved)