Increased visual information gain improves bimanual force coordination.

Bimanual force control requiring asymmetrical forces between limbs is more challenging than bimanual force control when the limbs produce symmetrical forces. Previous studies investigated visual information gains between 8 and 80 pixels/N to facilitate asymmetrical force control. Given that previous studies limited visual information gain to 80 pixels/N, the current experiment expanded the range by increasing visual information gains (8, 80, 256, and 512 pixels/N). A second manipulation involved three task constraint coefficients imposed on bimanual force control: (a) left-biased, (b) right-biased, and (c) equal-biased. Analyses of 15 right-handed adult volunteers revealed a decrease in bimanual force variability and more negative correlation coefficient with increased visual information gain in the equal biased condition. Significant reductions in bimanual force variability were found between 8 and 80 pixels/N. In contrast, significant improvements in coordination patterns between hands continued up to 256 pixels/N. These novel findings demonstrate that bimanual force coordination was more sensitive to an increase in visual information gains (>80 pixels/N) than bimanual force variability.