Failures of information to reduce rated aversiveness of unmodifiable shock

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Abstract
In Exp. I, information about shock onset times was varied between 3 groups of 30 Ss where shocks were, respectively, predictable by temporal signalling (Cond. I: constant 20‐sec. inter‐shock intcrval), unpredictable (Cond. II: inter‐shock intervals varied from 10–30 sec.), and predictable by conventional signalling (Cond. III: tone or light preceding each irregularly presented shock by 5 sec.). A form of the probe‐stimulus (PS) technique was used to obtain independent measures of fear. Rated aversiveness of shocks did not vary as a function of information (Conds. I, II, and III). There was, however, reliable evidence for the presence of conventionally‐signalled conditional fear under Cond. III. In Exp. II, to avoid a possible source of confounding, the PS technique was not used. Conds. I and II were readministered to two new 30‐Ss groups. Information again failed to reduce the rated aversiveness of temporally signalled shocks. Moreover, the two concomitant, shock‐elicited, autonomic measures, GSR and digital volume pulse change, failed to show a differential rate of decline as a function of information (Conds. I vs. II), although both measures declined reliably over trials.