Is Hand Selection Modulated by Cognitive–perceptual Load?

Previous studies proposed that selecting which hand to use for a reaching task appears to be modulated by a factor described as “task difficulty”. However, what features of a task might contribute to greater or lesser “difficulty” in the context of hand selection decisions has yet to be determined. There has been evidence that biomechanical and kinematic factors such as movement smoothness and work can predict patterns of selection across the workspace, suggesting a role of predictive cost analysis in hand-selection. We hypothesize that this type of prediction for hand-selection should recruit substantial cognitive resources and thus should be influenced by cognitive–perceptual loading. We test this hypothesis by assessing the role of cognitive–perceptual loading on hand selection decisions, using a visual search task that presents different levels of difficulty (cognitive–perceptual load), as established in previous studies on overall response time and efficiency of visual search. Although the data are necessarily preliminary due to small sample size, our data suggested an influence of cognitive–perceptual load on hand selection, such that the dominant hand was selected more frequently as cognitive load increased. Interestingly, cognitive–perceptual loading also increased cross-midline reaches with both hands. Because crossing midline is more costly in terms of kinematic and kinetic factors, our findings suggest that cognitive processes are normally engaged to avoid costly actions, and that the choice not-to-cross midline requires cognitive resources.