title: Investigation of task performance variations according to task requirements and alertness across the 24-h day in shift workers.
abstract: The study investigated time-of-day effects on task performance in shift workers in different tasks (reaction time, discrimination, probe recognition, free recall), by varying task-specific features. On each of six recordings, each programmed on a different day and in a randomised order, operators rated alertness and performed different tasks. Self-rated alertness varied according to a typical diurnal trend. Time of day also affected reaction time (slower responses at 03:00 hours), discrimination performance (lower accuracy at 03:00 hours in the most difficult condition) and recall (superior recall at 07:00 and 11:00 hours following deeper processing at encoding). The data demonstrated time-of-day effects on cognitive processes also involved in many real-job activities, despite the lack of control for a number of exogenous factors known to interfere with performance in work settings. Since in the cognitively more loaded tasks, time-of-day effects depended on task conditions, the findings are of operational concern in shift-work situations involving differential task requirements. In a real-job setting, performance variations were observed according to time of day and task requirements in a set of cognitively more or less demanding tasks. Task-specific research across the 24-h day enables a better understanding of operators' tasks and the development of supporting technology.
authors.affiliation: Universite Toulouse, Toulouse cedex 9, France.
authors.forename: E
authors.initials: E
authors.lastname: Galy
authors.forename: C
authors.initials: C
authors.lastname: Mélan
authors.forename: M
authors.initials: M
authors.lastname: Cariou
mesh_terms: D000328:Adult; D005602:France; D006801:Humans; D008297:Male; D008875:Middle Aged; D011795:Surveys and Questionnaires; D013647:Task Performance and Analysis; D014851:Wakefulness; D014940:Work Schedule Tolerance