Movement refractoriness: The influence of response structure and speed

In the first experiment, refractoriness of a primary arm swing was studied using two movement speeds and three secondary responses (reversal, contralateral and ipsilateral thumb-lift). Pre-movement inter-stimulus intervals were 100, 200 or 300 msec and response-stimulus intervals ranged from zero to 200 msec. Accelerometers provided kinematic data. The second experiment repeated the reversal condition with the addition of EMG analysis.The prediction that the maximal speed condition would show a general intensification of control processes, and thus less refractoriness as compared to submaximal speed, was upheld for all response conditions. The findings also supported the prediction that the pattern of refractoriness depends on the functional relationships of the muscles concerned.The EMG analysis revealed that while the sequencing of muscle action was unchanged with movement speed, its phasing characterized the shifts in response metrics. The overall findings emphasize the need to view the refractoriness phenomenon in the context of anatomical and mechanical consequences of force changes in controlling limb movement as they interact with intentional command.     

STAR: A unique embedded performance assessment technique

STAR (The Strategic and Tactical Assessment Record) is a versatile research tool designed to evaluate the effects of sustained performance and other stressors on integrated, complex cognitive functioning. This completely automated task is presented in the form of a highly motivating computer game. However, unlike typical computer games, successful performance of STAR depends on an individual’s ability to rapidly and accurately assess risk/benefit ratios in a variety of situations, and on the skilled use of an array of multipurpose control systems. STAR is unique in that approximately 80 performance measures are unobtrusively embedded in the operations required to “play the game”; no obvious performance assessment interferes with task presentation. STAR provides multiple measures of psychomotor function, attention, memory, information processing, decision making, risk-taking behavior, subjective state, errors, and error paths. In this report, we describe STAR, and summarize two preliminary experiments designed to separately evaluate the effects of task difficulty and task stress level on complex performance.