TASK CONSTRAINTS AND FUNCTIONAL MOTOR-PERFORMANCE OF INDIVIDUALS WITHAND WITHOUT MULTIPLE-SCLEROSIS

The interaction between informational support or task constraints and functional motor performance was explored using kinematic profiles of the arms and hands of 40 participants with and without multiple sclero sis (MS). Three functional tasks were performed under three conditions : impoverished (i.e., participants mimed the tasks), partial (i.e., pa rticipants mimed the tasks with a limited array of the objects normall y used), and natural (i.e., participants performed the actual tasks). Results indicated that each of the three conditions elicited unique ki nematic profiles. Movement time, maximum displacement, and velocity va riability were significantly different among each of the three conditi ons. An ecological interpretation suggested that functional performanc e emerged from the interaction of the task demands of each condition a nd of the action capabilities of the participants. Participants with a nd without MS responded to the three conditions in similar ways, excep t that those with MS performed the tasks more slowly. We speculated th at the slower performance was a function of the reduced and inconsiste nt action capabilities of the participants with MS.