Disruption of a Position-Reversal Learning Set in the Rat

Abstract

Nineteen rats were required to learn a series of 15 position-reversal problems in a T-maze (Phase A) and were then assigned at random to two groups. The acquired position-reversal set (PRLS) was then subjected to disruption over 80 trials in which different reward treatments operated for each group (Phase B). For a further 150 trials following the disruptive phase, the initial conditions were reinstated (Phase C). Results showed that rats receiving non-reinforcement during Phase B returned to the asymptotic performance recorded in Phase A within 2-3 reversal problems while those receiving 20 per cent, random reinforcement during Phase B failed to re-acquire the PRLS within 15 reversal problems. The results indicate that random 20 per cent, reinforcement, applied after establishment of a PRLS in rats, displaces by persistent random-responding, the “Win-stay-Lose-shift” hypothesis appropriate for PRLS attainment.