Emotionality in selectively bred strains of rats mediates prior shock effects on escape-avoidance conditioning.

Rats of the Maudsley Reactive and Maudsley Non-reactive strains were given 25 trials of escape-avoidance conditioning after exposure to inescapable shock. Prior shock exposure (PSE) did not affect avoidance or escape latencies, but decreased the number of avoidances made by the Maudsley non-reactive animals and increased the number of their failures to escape. The results are interpreted as demonstrating an interference with the classical conditioning of a conditioned emotional response, through a reduction in the information content of the CS following PSE. The strain differences are interpreted as due to the non-reactive animals being especially sensitive to PSE.