Thirty colonies, each consisting of a female and two male adult albino rats, remained intact for an a-week period. Naive conspecific intruders were then introduced into each colony for a 10-min test for 5 consecutive days. Videotapes of the tests were scored for aggressive and defensive behaviors. In every colony, aggression was greatest for a single alpha male. The alpha rats were randomly given one of three treatments: wheel-turn escape training, inescapable yoked shock, or restraint without shock. The alpha rats were then returned to their colonies and an intruder test was given 26 h later. Significant decreases in aggressive responses and increases in defensive behaviors occurred in the alpha yoked group but not in the other alpha groups. The nonalpha colony partners of the alpha yoked rats showed the opposite changes following the treatment. A final intruder test 72 h later revealed that the deficits in aggression of the alpha yoked group were still present but that the behaviors of most of the other groups were beginning to return to their respective pretreatment levels. These findings were discussed in terms of the concept of learned helplessness and alternative theoretical explanations.The finding that prior exposure to inescapable, as opposed to escapable, shock can have dramatic behavioral and physiological consequences has generated much research and theoretical interest (cf. Maier & Seligman, 1976;Sklar & Anisman, 1981). The presentation of inescapable shock has been shown to interfere with the ability of a variety of speciesto later learn a novel response to escape shock (e.g., Anisman, Suissa, & Sklar, 1980;Maier, Albin, & Testa, 1973;Overmier& Seligman, 1967) or to' learn an appetitive operant task (Rosselini, 1978). Transituational deficits resulting from inescapable shock have also been found in tests of nonassociative or unlearned behaviors, such as nonreinforced shuttlebox running (e.g., Maier, Coon, McDaniel, Jackson, & Grau, 1979) and tail flicks to nociceptive stimuli (e.g., that shock-elicited aggression reflects attack or aggressive tendencies has been vehemently challenged on a number of grounds by Blanchard and his col- . First, the specific behaviors typically seen during shock-elictied aggression are very similar to those shown by colony intruder rats under attack and do not resemble the fighting pattern of a dominant male resident in an established colony. Second, the forelimb movements that have typically been interpreted as "striking" during shock-elicited aggression have been shown to partially represent uncontrolled movements elicited by the footshock when the forelimbs are suspended or when the rat is engaged in defensive boxing. Third, the majority of the bites and wounds made by rats during elicited aggression are directed at the conspecific's head region. This target area is far more typical of the defensive behavior of an intruder than the attack fighting of a dominant male in a colony setting.In addition to being a questionable measure of attack behavior, elicited aggressi...