Differentiation of escape and avoidance responding in rats.

Examined escape and avoidance performance in 144 female Holtzman albino rats by factorially arranging immediate or postponed CS and UCS termination with shuttle or bar-press escape and avoidance responses. High levels of avoidance responding occurred only when the shuttle response (running) was both the escape and avoidance response, perhaps reflecting that rats are prepared to run but contraprepared to bar press when threatened by aversive stimulation. In addition, postponed UCS termination reduced avoidance performance drastically while CS termination conditions were without effect. Measures of UCS duration and clock terminations also indicated that immediate UCS termination was superior to postponed termination but additionally showed that this was so because postponed termination seriously impaired escape behavior. Results have particular relevance for how escape responses become anticipatory. (PsycINFO Database Record (c) 2010 APA, all rights reserved)