Workload and strategic adaptation under transformations of visual-coordinative mappings

Six right-handed male volunteers performed a bi-manual pursuit tracking task. Unknown to the subject, the mapping between both the absolute and relative motions of each control lever changed between trials, and could also change within a trial. There were four conditions which remained constant within a trial and four others which switched between combinations of the first four mappings. These eight total mappings could be performed under either a fast or slow target speed giving sixteen possible conditions, the order of administration of which was randomized across the subjects. Performance was assessed through the use of root mean square error (RMS) and percent time-on-target (TOT). Workload was derived from subjective report using the NASA Task-Load Index. Performance results differentiated three different groups within the mappings. The first group represented conditions in which despite scaling factors, the movement of the cursor remained consistent with the movement of the controls and was directly mapped. The second group, consisting of only two conditions, also presented internal consistency except that the movements of the cursor were mirrored in the movements of the controls, a direct but inverted map. The third group represented those conditions in which at least one period of performance decoupled the actions of the two controls. In general, workload distinguished the ordering of difficulty of the conditions, except that there was evidence of dissociation between performance and subjective evaluation in the three most difficult decoupled conditions. Verbal report of performer strategic behavior was elicited. Each line of evidence is considered in the attempt to understand how subjects explored the perceptual-motor space for strategic solutions when presented with the autonomy to do so.