Johnson, A. N., Vohra, S., & Shinohara, M. (2009). Interference from divided attention with additional motor or cognitive task to motor accuracy. ACSM 56th Annual Meeting, Seattle, Washington, Presentation Number 2698.

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This study investigated the influence of divided attention with an additional motor or cognitive task on accuracy of isometric force matching with a hand muscle. Healthy right-handed adults (N = 10) performed a unilateral motor task with the right hand, a cognitive task, a bilateral motor task with both hands, and a concurrent motor-cognitive task in a randomized order. The motor tasks involved steady low-intensity isometric contractions of the first dorsal interosseus in the right or both hands. Abduction force of the index finger was recorded from both hands. In the unilateral motor task, Ss received visual feedback of force and were instructed to match and maintain 5% and 10% of their maximal voluntary contraction force as accurate and steady as possible by abducting the index finger of the right hand. The bilateral motor task used the same protocol as the unilateral task but with both hands concurrently. The cognitive task involved arithmetic and memory. The concurrent motor-cognitive task corresponded to the concurrent performance of the unilateral motor and cognitive tasks. The abduction force for the steady 10-second period in the right hand was used for analyses. As an index of accuracy, the relative deviation of mean force from the target (error ratio) was calculated and averaged across four trials in each task.

The error ratio in the right hand tended to increase with an additional task at 5% and 10% maximal voluntary, but those changes did not reach statistical significance.

Implication. Divided attention with an additional motor or cognitive task induced little interference to motor accuracy during a low-intensity motor task with simple steady isometric contraction of a hand muscle.

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