Haloperidol and nonreinforcement produce different patterns of response slowing in a food reinforced runway task.

Rats were trained to traverse a runway for food reward and speeds were measured in the start, run and goal segments of the alley. After eight days of acquisition training, subjects were tested for four days under conditions of either extinction or haloperidol pretreatment. Although both haloperidol and extinction produced a suppression of the running response, the pattern of this suppression in the three alley segments was quite different for the two conditions. Haloperidol tended to be more effective than extinction in slowing start speeds but less effective than extinction in reducing run and goal speeds. This differential effect of haloperidol and extinction on speeds in different alley segments provides further evidence that haloperidol-induced impairments in performance cannot result entirely from a blunting of primary reinforcement.