Response suppression in rats: a comparison of response-contingent and noncontingent punishment and the effect of the minor tranquilizer, chlordiazepoxide.

A comparison of the behavioural effects of response-contingent and noncontingent shock was carried out in a series of experiments examining (a) suppression of an operant response (lever-pressing); (b) release from suppression following injection of the minor tranquilizer chlordiazepoxide, and (c) suppression of behaviour in a situation not associated with shock. The major findings were that response-contingent shock produced far greater suppression of the operant response than did noncontingent shock, as well as greater suppression of behaviour in a neutral environment following the shock experience. Chlordiazepoxide was found to be far more effective in releasing behaviour from suppression when shock was response-contingent than when shock was noncontingent, a result which does not appear to reflect simply the greater suppression produced by response-contingent shock. A discussion of methodology and interpretations in this field, suggests why discrpancies have arisen in the past.