Punished and classical-trial extinction of avoidance in gerbils following partial and continuous reinforcement.

Abstract

Summary.-Four groups of gerbils received either partial or continuous reinforcement during avoidance acquisition followed by either classical trials (CS-US pairings) or punishment in extinction. Partial reinforcement produced greater resistance to both classical-trials extinction and punishment than continuous reinforcement. Punishment produced more rapid extinction than classical trials following continuous reinforcement, while following partial reinforcement, vunishment facilitated performance relative to classical trials. - The results were related to the effects of delay of punishment, delay of CS termination, and the phenomenon of self-punitive behavior. In a previous study (Galvani, 1971), gerbils trained under eicher partial or continuous reinforcement showed more rapid extinction of shuttle avoidance responding when exposed to classical trials (CS-US pairings) with inevitable shock than when given regdar avoidance extinccion trials on which the US was omitted whether or not S responded. These findings were attributed to punishment suppression resulting from delayed punishment on classical trials. Specifically, a 5-sec. CS-US interval was employed in acquisition and extinccion. Any CR made on a classiczl trial was therefore followed in a few seconds at most by an inescapable shoclt In view of Karnin's ( 1959) evidence for a delay of punishment gradient, one might predict immediate punishment would produce more rapid suppression of avoidance responding than the classical-crial procedure. The presenc investigation tested this prediction. In addition, the present experiment was conducted to determine whecher animals acquiring the avoidance response under partial reinforcement would be more resistant to punishment than Ss receiving continuous reinforcement. Galvani ( 197 1 ) previously found partially reinforced Ss were more resistant to exciaction (PRE) than continuously reinforced Ss under both the classical-trial and regular-avoidance extinction procedures.