Electroconvulsive shock (ECS) produces a loss of memory for the immediately preceding period, but also produces non-amnesic effects which seriously complicate the interpretation of behavioral results following convulsions. The results of the present investigation indicated that the retrograde amnesia produced by ECS is probably slight, but appears enhanced in passive-avoidance tasks and diminished in aversively-motivated tasks requiring movement, because of a concomitant impairment of movement-inhibiting mechanisms. If this interpretation is valid, it is extremely difficult to make quantitative estimates of the degree or temporal extent of the retrograde amnesia induced by ECS in animals. It may be possible, however, to separate memory mechanisms from movement-inhibiting mechanisms with procedures involving more localized effects upon the brain. / Thesis / Doctor of Philosophy (PhD)