In 2 experiments, the authors independently varied the degree of cognitive and perceptual difficulty of suprapostural tasks. Participants were 23 students in Experiment 1 and 15 in Experiment 2. Increases in perceptual difficulty tended to be correlated with decreases in the variability of postural sway, consistent with the hypothesized functional integration of postural control with suprapostural tasks. Sway variability was not influenced by changes in the cognitive difficulty of tasks when perceptual difficulty was held constant, contrary to predictions derived from the perspective that postural and suprapostural activities compete for a limited pool of central processing resources. The results underscore the need for researchers to differentiate between suprapostural tasks that require perceptual contact with the environment and those that do not.
Bibliographical noteFunding Information:
Enactive Interfaces, a network of excellence (IST Contract No. 002114) of the Commission of the European Community and grants from the National Science Foundation (BCS-0236627 awarded to T. A. Stoffregen and CMS-0432992 awarded to M. Riley) supported preparation of this article. We are grateful to Joel Warm for instruction and consultation on the use of the NASA-TLX. We thank Gerry Matthews, whose comments inspired the study, and Valerie Never-man, who helped with data collection and analysis. Experiment 2 was conducted as part of Philip Hove’s master’s thesis. Portions of the data were reported at the XIth International Conference on Perception and Action, Storrs, CT, July 2001.
- Visual performance