The challenge of uncoupled motion: duration of cognitive and physiological aftereffects.
This study aimed to document the cognitive aftereffects of exposure to uncoupled motion and the time course of recovery from these aftereffects. Uncoupled motion refers to a situation in which an individual is simultaneously exposed to two asynchronous motions, either real or virtual. These environments are a challenge for designers because technology that is supposed to increase the user's task performance may actually lead to decreased task performance. In the study, 11 male participants, (median age =32 years) with prior flight experience (median=600 hr) were exposed to an uncoupled motion environment consisting of a flight simulator on a vertically oscillating platform. Participants completed a cognitive test battery, a balance test, and a dynamic visual acuity test preexposure, immediately postexposure, and 2, 4, 6, 8, and 24 hr postexposure. The uncoupled motion scenario led to significant cognitive aftereffects that cannot be solely attributed to motion sickness. These aftereffects lasted between 2 and 4 hr postexposure. The scenario generated some physiological aftereffects that lasted between 1 and 2 hr postexposure. However, it is likely that these aftereffects can be attributed to motion sickness. Uncoupled motion can cause unappreciated effects, such as degraded cognitive performance. System designs that create uncoupled motion need to be evaluated for the potential to generate operator impairment, and designs should be modified to minimize this potential wherever possible. When redesign is not possible, system-use guidelines should be developed to minimize impairment. The current results suggest operators avoid performing cognitively demanding tasks for at least 2 hr postexposure.