The effect of water deprivation on shock-escape impairment after exposure to inescapable shock

Abstract

Water deprivation during inescapable shock exposure and a shuttle escape test 24 hours later (Experiment 1), during shuttle escape training only (Experiment 2), or during inescapable shock exposure only (Experiment 3a), ameliorated the shock-escape impairment normally seen following exposure to inescapable shock. The results of Experiments 1 and 2 could be attributed to increased activity produced by water deprivation during the shuttlebox test. However, the results of Experiment 3a suggest that water deprivation during inescapable shock exposure can eliminate the shock-escape impairment in a shuttlebox test 24 hours later. These results are discussed in relation to the motivational deficit predicted by learned helplessness theory. Prior exposure to inescapable shock often interferes with or impairs later escape or avoidance acquisition. Learned helplessness theory (Maier & Seligman, 1976; Seligman & Maier, 1967) suggests that these effects are produced by both an associative and a motivational or activity deficit. The associative deficit is attributed to an expectancy, formed during exposure to uncontrollable aversive events, that responses and outcomes are independent, and it is manifested by a failure to learn a contingent relationship when subsequently exposed to a situation where escape or avoidance is possible. The motivational deficit is inferred from the reduced probability that the organism will initiate a response following exposure to uncontrollable aversive events. According to this theory, then, exposure to uncontrollable aversive events produces a condition where an organism is both less likely to initiate responding and is less likely to learn a responseoutcome contingency, even if responses occur. One investigation of the contribution of the motivational deficit to the shock-escape impairment seen in the traditional shuttlebox test was provided by Jackson, Maier, and Rapaport (1978), who exposed rats, pretrained with inescapable shock, to three different levels of test shock