TESTS OF TWO HYPOTHESES OF SHOCK-RIGHT FACILITATION

Two experiments were done to determine how shock for the correct response improves the performance of rats in visual discrimination learning. The first experiment tested but did not confirm Muenzinger's hypothesis of in-creased exposure to the critical cues. The second experiment tested the hypothesis of secondary reinforcement. Rats were pretrained in a runway to shock correlated with food reward. In a subsequent light-dark discrimi-nation problem, those 5s shocked for correct responses did slightly but not significantly better than controls, while those Ss shocked for wrong ones did worse (p<.02), confirming the hypothesis. The present study continues the inquiry, started by Muenzinger (1934) and taken up by Wischner (1947) and Fowler (in press), into the facilitating effect of shock for cor-rect responses in discrimination learning (see Fowler, in press; Fowler & Wischner, 1969, for reviews). Muenzinger, training rats to choose the lighted side of a T maze, found that a group shocked for correct choices did almost as well as a group shocked for errors and much better than one with no shock at all. He advanced the theory, supported in a well-known series of experi-ments, that shock, by delaying 5 " at the choice point, caused longer exposure to the critical cues. In later experiments, prompted by Wisch-ner's (1947) negative results, Muenzinger modified without relinquishing his position. Replacement of his correction procedure by a hybrid form of "noncorrection " sharply re-duced the "Muenzinger effect " (Muenzinger & Powloski, 1951), but preliminary habitu-ation to shock restored it (Muenzinger, Brown, Crow, & Powloski, 1952). Muen-zinger conceded that two factors were prob-ably involved: a general cue-accentuating function of shock and a specific avoidance function. Shock avoidance should impair the per