The rotary pursuit test is not an index of normal psychomotor function in humans

Abstract

Objective: This study sought to assess whether the rotary pursuit test is a good indication of the psychomotor performance of human subjects during normal working hours. Circadian hormonal profiles of salivary melatonin and cortisol were also established for correlation with performance. Methods: Ten healthy individuals working in the Department of Obstetrics and Gynecology laboratory participated in this study. The experiment was conducted during a normal 8.5-hour working day in which routine laboratory tasks such as running radioimmunoassays were performed. Saliva samples were collected every 2 hours starting at 8:00 a.m. Simultaneously, self-rated questionnaires on mood states, sleepiness, stress, and types of food and drinks consumed were also recorded. At 10:00 a.m., 12:00 noon, 2:00 p.m., and 4:00 p.m., the subjects' were tested on the rotary pursuit machine, on which their ability to track a rotating target with a stylus was tested by means of measuring the time the stylus stays on target. Results: The circadian profiles of salivary melatonin and cortisol were similar to what previous studies have shown. Increases in cortisol levels were associated with food intake, work stress, or spontaneous awakening. Tracking performance (time on target) improved significantly from 10:00 a.m. to 2:00 p.m. and then decreased nonsignificantly at 4:00 p.m. only at the speed setting of 60 rpm. There was no correlation between the three parameters measured. Summary: Variation of psychomotor performance during a normal working day and in noncircadian disrupted individuals cannot be measured by the rotary pursuit test. Furthermore, a learning effect could mask any variation in performance.