A brief manual control test and decision strategy have been developed, laboratory tested, and field validated, which provide a means for detecting human operator impairment from alcohol or other drugs. The test requires the operator to stabilize progressively unstable controlled element dynamics. Control theory and experimental data verify that the human operator's control ability on this task is constrained by basic cybernetic characteristics, and that task performance is reliably affected by impairment effects on these characteristics. Assessment of human operator control ability is determined by a statistically based decision strategy. The operator is allowed several chances to exceed a preset pass criterion. Procedures are described for setting the pass criterion based on individual ability and a desired unimpaired failure rate. These procedures were field tested with an automobile-installed apparatus designed to discourage drunk drivers from operating their vehicles. This test program, sponsored by the US Department of Transportation, demonstrated that the control task and detection strategy could be applied in a practical setting to screen human operators for impairment in their basic cybernetic skills.

Reviewed in this paper are the development and validation of a behavioral testing device that can detect human operator impairment. These skills are important in performing tasks that require continuously manipulating displayed variables with a control device, such as driving or machinery operation. The manual control skills required to perform these types of tasks have been extensively studied (.! _), and the test described herein has been developed to detect impairment in these skills. The test involves two components: a control task and a detection strategy. The control task, called the Critical Tracking Task (CTT), was developed in the early 1960s to test the visual motor performance of pilots and astronauts (£,~). Over the years, it has proven to be an effective indicator of the effects of environmental stresses [eg, noise C! l, space station confinement (? _l, ship motion (§ _), spacecraft re-entry Cllr and human operator impairment (_!!,~) J•