Sustained attention when squatting with and without an exoskeleton for the lower limbs

Twelve Royal Marines participated in a laboratory study of a passive lower limb exoskeleton. Participants stood for 5 min in a semi-squatting posture in the laboratory while performing the Sustained Attention to Response Test (SART), repeated on separate days while wearing and without the exoskeleton. Performance on the SART was degraded when the semi-squatting posture was adopted and did not recover after 15 min of rest. The SART was rated as less frustrating when the exoskeleton was worn, while less time pressure and task conflict were reported and the need to exert self-control to maintain the posture was rated lower. There was no effect of the exoskeleton on SART performance. However, subjects' increase in heart rate when squatting, without the exoskeleton, was positively correlated with an increase in their SART error rate. The findings are discussed in relation to the cognitive demands of performing physically demanding tasks and the possibility that new technologies designed to enhance human physical ability may also improve cognitive capacity.