Preference-for-signaled-shock phenomenon: Effects of shock modifiability and light reinforcement.

Abstract

Conducted 2 experiments in which rats were given a choice between a lever correlated with white noise signaling inescapable shock and a lever correlated with unsignaled, inescapable shock. In Exp I, Ss were 30 Sprague-Dawley and 30 Wistar male rats. Signaled shock was preferred only when delivered through unscrambled foot grids (modifiable shock); no such preference occurred when shock was presented through scrambled foot grids or through fixed (tail) electrodes (unmodifiable shocks). Interpretation of the preference in terms of S-produced modification was directly supported by the finding of a significant correlation between degree of preference for signal and amount of unauthorized modification of signaled (unscrambled) shock. In Exp II, using a light stimulus correlated with signal for inescapable shock, 40 Sprague-Dawley Ss showed a preference for light completely accounted for by the light per se rather than by the indicator value of this stimulus. (PsycINFO Database Record (c) 2006 APA, all rights reserved)