Early coping experience and later aversive conditioning in cats

Kittens were given differential early experience in order to compare an objective coping behavior with the result of an inescapable aversive experience. Separate groups of kittens were treated in a shock motivated runway task at either 4 or 12 weeks of age, by allowing one member of a weight matched sibling pair to acquire an escape behavior, while the other member was confined; a third subject served as a handled control. Escape behavior was significantly different for 4 and 12 week old subjects, since the older kittens reached a running asymptote within the first few shock trials. At 6 months of age, the subjects were tested for effects of differential early treatment; heart rate, respiration rate and amplitude, and somatic activity were measured during classical conditioning. While all groups gave evidence of acquisition in one or more response measures, only a potentiated heart rate response in 4 week kittens could be related to early experience. Heart rate did not differentiate escaping kittens from confined ones. Rather, heart rate was related to early treatment with shock, perhaps reflecting an increased tendency to react with a passive defensive response.