Fifteen healthy male volunteers received single doses of 100 mg immediate release remoxipride (IR), 150 mg controlled release remoxipride (CR), 50 mg chlorpromazine (CPZ), 2 mg lorazepam (LZ), and placebo in a randomised, five-period cross-over study. Both saccadic (SEM) and smooth pursuit eye movements (SPEM) as well as a battery of psychomotor performance tests were assessed at 1.5-h intervals over 9 h following drug administration. The areas under the response-time curves and the maximum effect during the study period were analysed by analysis of variance. The most consistent impairments were produced by LZ. The neuroleptics caused impairments to SEM, and tended to impair critical flicker fusion, continuous attention and both paced and unpaced versions of the digit-symbol substitution test as well as subjective measures of sedation. Only LZ impaired SPEM. Neither paced nor unpaced psychomotor tests distinguished between neuroleptics and benzodiazepines. The low therapeutic doses of IR and CR produced similar impairments to a sub-therapeutic dose of CPZ. Selectivity of pharmacological action does not appear to predict selectivity of effect on psychomotor function.

Measures of variability are rarely quoted in drug studies of psychomotor function. Five recent studies were therefore analysed to calculate the coefficients of variation for different tests of psychomotor function, both during and between study days. Saccadic eye movement analysis and critical flicker fusion threshold were found to have low coefficients of variation (ranging from 2.7 to 7.5 per cent) while visual analogue rating scales and the digit symbol substitution test were found to have much higher coefficients of variation (ranging from 7.9 to 17.6 per cent). It is suggested that measures of test variability be routinely assessed in psychomotor studies as a check on test methodology.

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An electro‐oculogram based eye tracking system (the Cardiff System for the Generation and Analysis of Saccades) was used to quantify smooth pursuit eye movements (SPEM) and saccadic intrusions in 20 chronic schizophrenic patients and 16 normal, healthy controls. Statistically significant differences were found between the two groups at all four target frequencies tested (0·2, 0·25, 0·33 and 0·5 Hz) in three measures of SPEM dysfunction (position error, velocity error and saccadic intrusions). Of the patients' position errors, 50–70 per cent were greater than the 95th percentile for controls. Velocity errors gave a similar range of SPEM dysfunction (50–65 per cent) but the frequency of saccadic intrusion abnormality was more variable (20–60 per cent). Position error and saccadic intrusions, at the fastest target speed, correlated with total BPRS scores. Extrapyramidal symptoms (Simpson and Angus) and abnormal involuntary movements also correlated with saccadic intrusions at 0·5 Hz. There were no significant correlations between SPEM dysfunction and age, duration of illness, negative symptoms (total SANS score) or current dose of antipsychotic drug treatment. Copyright © 1999 John Wiley & Sons, Ltd.