ABSTRACT
Levels of aggression are also affected by the type of rearing background. For example, animals reared for their first few months in impoverished environments, such as social isolation, typically show higher levels of aggression towards conspecifics than those reared by their mothers (Mitchell, 1968; Mitchell & Clark, 1968). Often, the previously isolated animals display aggression towards inappropriate targets. For example, instead of decreasing aggression as they become familiar with age-mates with whom they have lived, isolates' levels of aggression may increase across episodes of cohabitation (Mitchell & Clark, 1968). Moreover, they fail to inhibit their aggression appropriately in order to prevent severe injury to their familiar age-mates (Mason, 1963). As further examples of inappropriate expression of aggressive behavior, small preadolescent isolates may show aggression towards a full-grown adult male (Harlow & Harlow, 1969; Mitchell, 1968; Suomi, 1982); they may direct unprovoked aggression towards unrelated infants (Mitchell, 1968), or in the case of adult female isolates abuse their own infants (e.g., see Ruppenthal, Arling, Harlow, Sackett, & Suomi [1976] for a review of these studies).
