Controllability and predictability are important modulators of the behavioral effects of aversive stimulation on animals. An experiment was conducted to further investigate both the immediate and proactive effects of controllability and predictability of shocks on adrenocortical responsivity. In an initial stress induction phase, the controllability and predictability of electric shocks were independently varied in groups of dogs, and plasma cortisol responses were measured. In a subsequent test phase, all groups of dogs received identical shocks in a novel situation. Cortisol responses to these test shocks were analyzed as a function of the controllability and predictability of previous induction shocks. The results showed that during stress induction, uncontrollable shocks produced significantly greater cortisol elevations that controllable shocks but that predictability had no significant effect on cortisol responses. However, unpredictable shocks during stress induction acted proactively to significantly increase cortisol response to novel test shocks, whereas prior controllability did not modulate subsequent responsivity to novel shocks.

In three experiments the specificity of an effective reactivation stimulus, or reminder, was examined. Two weeks after learning to produce movement in a crib mobile by footkicking, 3-month-old human infants showed no retention of the response-reinforcer contingency. A reactivation procedure 24 hours prior to the long-term retention test was effective if the reminder was a brief noncontingent exposure to the original 5-component training mobile or a mobile containing one novel substitution. When more than one novel component were substituted into the original mobile, the reminder was ineffective. This was predicted by the discrimination function 24 hours following training. A reminder containing only a single familiar (predictive) component and four novel ones was also moderately effective. In subsequent studies, we explored different interpretations of the reminder specificity effect. We hypothesize that reminder specificity is of particular adaptive value for developing organisms in providing a buffer against memory retrieval in inappropriate contexts.

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