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Franklin Henry's "memory drum" theory of neuromotor reaction (Henry & Rogers, 1960) was one of the most influential studies of the response programming stage of information processing. The paper is the most-cited study ever published in the "Research Quarterly for Exercise and Sport." However, few people know there is a noteworthy error in the paper, namely in the description of the C movement, the most complicated of the three responses studied. Henry himself was unaware of the error for nearly 20 years after the paper's publication. The purpose of our paper is to accord the factual record its due respect by revealing the history about the error and its correction. The data are in the form of the original 1960 paper which describes the C movement, a paper by Howell (1953), and personal letters from Henry dating from 1979, when the error was first discovered, and continuing through 1986. In one letter, Henry attributed the error to a mild and specific form of aphasia, manifested by word reversals, from which he suffered throughout his scholarly life. Such a revelation makes the career of this remarkable scholar even more remarkable. (Contains 2 figures and 1 note.)

This study was designed to determine if movement planning strategies incorporating the use of visual feedback during manual aiming are specific to individual movements. Advance information about target location and visual context was manipulated using precues. Participants exhibited a shorter reaction time and a longer movement time when they were certain of the target location and that vision would be available. The longer movement time was associated with greater time after peak velocity. Under conditions of uncertainty, participants prepared for the worstcase scenario. That is, they spent more time organizing their movements and produced trajectories that would be expected from greater open-loop control. Our results are consistent with hierarchical movement planning in which knowledge of the movement goal is an essential ingredient of visual feedback utilization.

Motor control schemes should have an element of control and an element of coordination. The former is a source of initiative and a product of the brain's work (mind, intelligence, or 'homunculus') while the latter can be viewed as a process with constraints emerging at a hierarchically lower, autonomous level. Limiting scientific analysis to an object smaller than the universe necessarily leads to a hierarchical (cybernetic) approach.

Redundancy of the motor control system is an important feature that gives the central control structures options for solving everyday motor problems. The choice of particular control patterns is based on priorities (coordinative rules) that are presently unknown. Motor patterns observed in unimpaired young adults reflect these priorities. We hypothesize that under certain atypical conditions, which may include disorders in perception of the environment and in decision making, structural or biochemical changes within the central nervous system (CNS), and/or structural-changes of the effectors, the central nervous system may reconsider its priorities. A new set of priorities will reflect the current state of the system and may lead to different patterns of voluntary movement. Under such conditions, changed motor patterns should be considered not pathological but rather adaptive to a primary disorder and may even be viewed as optimal for a given state of the system of movement production. Therapeutic approaches should not be directed toward restoring the motor patterns to as close to 'normal' as possible but rather toward resolving the original underlying problem. We illustrate this approach using, as examples, movements in amputees, in patients with Parkinson's disease, in patients with dystonia, and in persons with Down syndrome. Keywords: coordination; Down syndrome; motor control; movement disorders; Parkinson's disease; posture; preprogramming; voluntary movement

A movement task was used to investigate the effects of precued variables on reaction time. The task involved rapid rotation of a hand-held manipulandum to target locations and required either pronation or supination of the forearm through short or long extent. The effects on reaction time of precues signalling target direction, extent, or a combination of direction and extent, were measured. The longest reaction times occurred when no information about direction or extent was provided in the precue (all parameters uncertain). Complete prior specification of target position produced the shortest reaction times. Specification of direction when extent was uncertain produced a significantly larger reduction in reaction time than specification of extent when direction was uncertain. Prior specification of extent also produced a small but significant reduction in reaction time relative to the condition in which direction and extent were specified in a mutually conditional manner. The results are discussed in relation to parameter precuing and motor programming, in which the direction is programmed by the pre-selection of neurons representing the muscles to be used in the task while programming of extent is represented by their level of activity during task performance. [ABSTRACT FROM AUTHOR]

Triphasic electromyographic (EMG) patterns have been described as characteristic of rapid, discrete, uniplanar, goal-directed movements. This experiment examined the effects of Response Type (experimenter- vs. subject-determined), Hand (preferred vs. nonpreferred), and Practice (early vs. late) on performance accuracy, and specific temporal EMG and kinematic measures during a dart throw. EMG was recorded from triceps (main agonist), brachioradialis, and biceps (main antagonist). The number of trials in which a triphasic EMG occurred varied systematically across conditions. The experimenter-determined, early practice condition resulted in greatest frequency (92%) of trials displaying a triphasic EMG and least accurate performance. In contrast, the lowest frequency (79%) of triphasic EMG and most accurate performance occurred in the subject-determined, late practice condition. The association among 14 temporal EMG, and kinematic measures for each trial of the dart throw was analyzed with multivariate factorial ANOVA. Four clusters of variables emerged: initial phase, braking phase, terminal phase, and movement speed and duration. Variables contributing to the initial-phase cluster were most strongly associated within the experimenter-determined, early practice condition, and the strength of association was directly related to diminished performance accuracy. Paradoxically, best performance accuracy (subject-determined, late practice) was identified with a weaker association among variables representing the initial phase. [ABSTRACT FROM AUTHOR]

In the monkey, reaction time in a precued delayed response task was found to be faster when the animals had to remember the precue than when it was continually available (Smyrnis, Taira, Ashe, & Georgopoulos, 1992). We investigated whether this reflects a general principle that applies to all types of precued tasks. However, we found the opposite result in a simpler task in humans. Our findings suggest that the beneficial effect of a memory requirement on reaction time in the monkey may reflect an effect of task difficulty, rather than a fundamental process involved in all precued movement tasks. [ABSTRACT FROM AUTHOR]

The effect of foreperiod length on reaction time in memorized (MM) and nonmemorized (NM), precued, delayed responses was investigated. Six subjects participated in one long and one short foreperiod schedule testing session. An aiming task, using elbow supination/pronation, in response to a visual stimulus was employed. In the MM condition, target spatial information was available for a fraction of the foreperiod duration. In the NM condition, target information was available continuously until the subject attained the target position. Subjects responded with a significantly longer latency in the long foreperiod schedule. Within each foreperiod schedule, the shortest foreperiod resulted in significantly longer reaction time. However, the absolute value of foreperiod did not have a major effect on reaction time latency. Memorization and nonmemorization conditions did not affect reaction time. [ABSTRACT FROM AUTHOR]

Introduces the selection of research papers in 'Motor Control' of 1998 issue. Citations on the interdisciplinary neuroscience fields in relevance to the study; Emphasis on the clinical aspects of motor control.

The reports by Fitts and Peterson [J. Exp. Psychol. 67(2) (1964) 103-113] and Klapp [J. Exp. Psychol. Hum. Percept. Perform. 104(2) (1975) 147-153] concerning the effects of movement amplitude and target diameter on reaction time present conflicting results. Fitts and Peterson reported that reaction time increased when movement amplitude was lengthened. Klapp reported an interaction in which target diameter effect on reaction time was moderated by movement length: for small targets, reaction time decreased with increasing movement length but reaction time remained unchanged (or increased modestly) when target diameter was large. Two experiments were conducted to replicate and examine the inconsistency in the reaction time results. For both experiments movement time results were in agreement with the predictions of Fitts' law. However, the results for reaction time were mixed: support was obtained for Klapp (1975) but not for Fitts and Peterson (1964). Further analysis identified several potential variables that could have influenced reaction time and explained the different effects on reaction time reported by Fitts and Peterson (1964) and Klapp (1975). The potential variables could include: limb posture at the start of a response; number of limb segments required to perform the task; and the effect of pooling reaction time data from targets located right and left of the start point, and from near and far targets.