Early Experience and Social Grouping in Fear Extinction of Rats

Abstract

Rats, conditioned to escape shock in a straight 6-ft. runway, were tested for the effects which early rearing and presence of different numbers of social animals had on fear-conditioned escape responses. The most significant findings were that: (a) for animals reared apart, the presence of another animal or animals had little or no effect upon fear-conditioned escape behavior; (b) for animals reared together, the presence of other animals resulted in fear reduction; (c) this fear-reducing influence of other animals seemed to have developed during the early life in a social situation; and (d) the group had to consist of at least three animals before its effects in fear situations were apparent.