Changing rearing environments and problem solving flexibility in rats

Rats were reared from weaning onwards in impoverished (IC), social (SC) or enriched (EC) environments. In addition, some groups were moved from an enriched to an impoverished environment, or vice versa, either once or three times during rearing. After 2 months of differential rearing, animals were tested in a multidimensional discrimination procedure in an operant chamber, where reinforcements were given on a random schedule, that is, uncorrelated with the choices made by the animals. It was found that eventually all rats took up alternating place. However, enriched subjects did so more consistently than impoverished or socially reared subjects. Animals shifted three times, behaved more routine-like than did animals never changed or changed only once; such animals did so to a greater degree than did the enriched animals. In comparison, impoverished animals, and those never changed or changed once, more often kept responding to the environmental cues. The results are discussed in relation to general interpretations of the effects of impoverishment and enrichment in terms of behavioural flexibility, over-attention, and in relation to styles of coping. It is argued that, contrary to welfare people's claims, the behavioural differences found are well within the range of normal individual variation.