Avoidance learning in rats: Genetic evidence for two distinct behavioral processes in the shuttle box.

Used an 8 * 8 diallel cross of rats (Roman high, low, and control avoidance; Maudsley reactive and nonreactive; Tryon maze bright and dull; and Wistar albino) to analyze sequentially a conditioned avoidance response (CAR) within a session of 30 trials. On early conditioning trials, the F1 hybrids scored fewer avoidances than the parental strains, whereas on later trials the hybrids were superior to parents. This finding was confirmed within a session of 100 trials in a 3 * 3 diallel and interpreted to mean that 2 distinct adaptive behavior patterns underlie shuttle-box CAR acquisition in rats. There appears to be a tendency to develop an adaptive inactivity or "freezing" behavior pattern and later, as conditioning proceeds, to develop an equally adaptive but more active behavior pattern of "fleeing." Implications for 2-process theories of avoidance conditioning are considered briefly. (20 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)