Cross-motivational effects of inescapable shock are associative in nature

Exposure to inescapable shock interferes with the subsequent acquisition of an appetitive operant. This deficit may be due to either associative interference or activity reduction from the inescapable shock pretreatment. The relative importance of these two factors was examined by using an appetitive response choice discrimination procedure and concurrently measuring activity. Experiment 1 demonstrated separate associative and activity effects of inescapable shock, in that the animals exposed to inescapable shock made more incorrect responses than controls and were lower in activity. Experiment 2 demonstrated that these effects resulted from the uncontrollability of the shock, not from shock exposure per se. In Experiment 3, residual effects of inescapable shock were investigated by exposing animals to discrimination reversals. On these tests, inescapably shocked animals showed performance inferior to nonshocked controls, a result indicating that the effects of inescapable shock are not completely reversed by experience with contingent reward in the discrimination task. No evidence of an activity deficit was observed during this discrimination reversal. These results strongly suggest that associative factors play a more important role than activity reduction in mediating the effects of inescapable shock, at least when these are measured in an appetitive context.