“…These are the competing motor response hypothesis (Levis, 1976;Glazer & Weiss, 19700, 1976b), the fear hypothesis (Jackson & Minor, 1988;Minor & LoLordo, 1984), and the norepinephrine-depletion hypothesis (Anisman, 1975;Weiss et al, 1981). The competing motor response hypothesis states that during an inescapable shock, inactivity is associated with and reinforced by the shock offset, and that activity is consequently reduced during the test task, which requires active responses to escape from shock.…”