THE EFFECTS OF HALOPERIDOL ON VISUAL-SEARCH, EYE-MOVEMENTS AND PSYCHOMOTOR PERFORMANCE

The effects of single doses of haloperidol (2, 4 and 6 mg) were compar ed with lorazepam 2.5 mg and placebo in 15 healthy subjects. Visual se arch strategy was measured, along with a range of psychomotor and eye movement tests. Patients with Parkinson's disease have been shown to e xhibit a shift from parallel to serial processing in visual search, bu t we demonstrated that this does not occur following administration of either haloperidol or lorazepam. Haloperidol was detected by visual a nalogue rating scales and peak saccadic velocity the latter being the more sensitive measure. Haloperidol had no statistically significant e ffect on smooth pursuit position error, velocity error or saccadic int rusions. Digit symbol substitution performance was clearly diminished by haloperidol, but there was no effect on the continuous attention te st. Lorazepam decreased performance in all tests apart from saccadic l atency.