Search Results

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.

The aim of this study was to assess the ability of young adults with and without Down syndrome (DS) with regard to attention orientation when detecting visual targets. The influence of advanced knowledge of target localization was examined when detection was (aiming task), or was not (detection task), followed by a movement toward the target. Participants were given advance information about the probability of target occurrence at expected locations. Results show that participants with DS benefit from attention orientation. However, they do not appear to use the same attentional strategies as participants without DS do when aiming is required. Analysis of the reaction times also revealed that participants with DS reacted faster in the aiming task rather than in the detection task.

The aim of this experiment was to explore the behavioral effects of various temporal pressures on the anticipatory postural adjustments (APAs) in a complex task. Eighteen handball players performed a handball direct throw in three conditions of temporal pressure: (1) a reactive condition (RC), the throw was initiated as quickly as possible following a visual stimulus; (2) an anticipation-coincidence condition (AC), by synchronizing the impact of the ball with the passage of a visual mobile on a target; and (3) a self-initiated (SI) throw. The whole-body postural oscillation and the acceleration of the wrist were measured before and during the throwing action. Results showed that the delays between the onsets of the postural and focal activities were significantly different between RC and both the SI and the AC conditions. Movement time, time to peaks (negative and positive), are shorter in the RC, intermediate in the AC, and longer in the SI condition. Variability was significantly larger in AC in comparison with RC and SI. These results support the existence of different control modes triggered by the temporal pressure; they demonstrate that these control modes can be generalized to complex intentional movements such as the throwing skill and to an anticipation-coincidence situation.

This study investigated the effect of hand movements on behavioral and electro-physiological parameters of saccade preparation. While event-related potentials were recorded in 17 subjects, they performed saccades to a visual target either together with a hand movement in the same direction, a hand movement in the opposite direction, a hand movement to a third, independent direction, or without any accompanying hand movements. Saccade latencies increased with any kind of accompanying hand movement. Both saccade and manual latencies were largest when both movements aimed at opposite directions. In contrast, saccade-related potentials indicating preparatory activity were mainly affected by hand movements in the same direction. The data suggest that concomitant hand movements interfere with saccade preparation, particularly when the two movements involve motor preparations that access the same visual stimulus. This indicates that saccade preparation is continually informed about hand movement preparation.

Two studies were carried out in order to examine the effectiveness of preperformance routines when learning a self-paced motor skill in volleyball. In Study 1, observational and verbal data were collected on elite male volleyball players in order to determine patterns of motor behaviors performed before they served the ball. In Study 2, beginning female learners were taught two variations of preperformance routines when learning the serve in volleyball: motor-emphasized and cognitive-emphasized. The routines were developed based on the data collected in Study 1. The data analyses revealed that the motor-emphasized learners were more accurate than the cognitive-emphasized learners in retention trials. It was concluded that it may be more beneficial for beginning learners to perform preparatory routines in which an emphasis is made on motor preparation.