Haloperidol affects stimulus-dependent strategies and not reward-dependent strategies.

In order to investigate effects of haloperidol on response strategies, rats were confronted with an unsolvable discrimination problem after being injected with haloperidol (0.1 mg/kg, IP) or its solvent. The results showed that haloperidol-treated rats displayed systematic behaviour to a lesser degree than the control rats. Haloperidol did not affect reward-dependent response strategies. However, haloperidol did affect stimulus-dependent response strategies. Haloperidol-treated rats showed more response strategies based on visual or auditory cues, and less spatial response strategies than control rats. It is concluded that this differential effect of haloperidol is the consequence of the different nature of the stimuli (discretely present visual and auditory stimuli versus constantly present spatial stimuli).