INFORMATION, COORDINATION MODES AND CONTROL IN A PREHENSILE FORCE TASK

Two experiments were performed to examine the relationship between deg rees of freedom for. action, precision of feedback, and prehensile for ce magnitude. Performance in the accurate maintenance of various grip forces was assessed in terms of root mean square (RMS) error and coeff icient of variation (CV). In Experiment 1 an interaction of grip coord ination mode, as defined by the number of digits used, and force magni tude, was observed both in the RMS and CV data. While the addition of digits at low force levels was correlated with a decrease in performan ce, the converse was true at the highest force level. Experiment 2 ext ended the basic conditions of Experiment 1 with the additional manipul ation of feedback precision. The findings revealed an interaction betw een information precision and coordination mode in determining fluctua tions in prehensile force performance. The interaction of grip coordin ation mode and information precision is consistent with the notion tha t the capacity for adaptive control is dependent upon the availability of biomechanical degrees of freedom for action and the degree of deta il available in information about criterion performance.