School of Psychology and Speech Pathology

This study investigated how 7 skilled table tennis players controlled velocity of a forehand drive stroke when the ball's trajectory, velocity, and spin were modified. They hit a target in response to balls launched under four different conditions. The relative and absolute times used in the backswing phase showed no significant differences among conditions. When subjects hit fastballs, there was a significant change in the time required for them to reach the peak of velocity in the forward swing phase. In addition, players decreased the velocity of their strokes to hit fast-approaching balls. These results indicate that highly skilled table tennis players need to adjust the striking velocity and striking time (relative and absolute) required to reach the peak of velocity in the forward swing phase for these task modifications. Since they used slower movement velocities to hit faster-approaching balls, skilled table tennis players may override this speed-coupling process.

The aim of this thesis was to investigate the time course of the processes of motor preparation that occur about 500ms prior to initiation of fast and brief interceptive actions.. More specifically, these processes involve to the preparation of movement parameters (amplitude and direction) and the triggering of interceptive actions both based on brief observations of a moving target during its final approach towards an interception zone. Chapter 1 provides an introduction to the research program and also reviews previous work - methods and main ...

Visual information is an essential guide when interacting with moving objects, yet it can also be deceiving. For instance, motion can induce illusory position shifts, such that a moving ball can seem to have bounced past its true point of contact with the ground. Some evidence suggests illusory motion-induced position shifts bias pointing tasks to a greater extent than they do perceptual judgments. This, however, appears at odds with other findings and with our success when intercepting moving objects. Here we examined the accuracy of interceptive movements and of perceptual judgments in relation to simulated bounces. Participants were asked to intercept a moving disc at its bounce location by positioning a virtual paddle, and then to report where the disc had landed. Results showed that interceptive actions were accurate whereas perceptual judgments were inaccurate, biased in the direction of motion. Successful interceptions necessitated accurate information concerning both the location and timing of the bounce, so motor planning evidently had privileged access to an accurate forward model of bounce timing and location. This would explain why people can be accurate when intercepting a moving object, but lack insight into the accurate information that had guided their actions when asked to make a perceptual judgment.► We investigated the impact of visual motion on perception and action. ► Perception was systematically biased in the direction of motion. ► Interceptive actions were accurate. ► Perception and action are based on qualitatively different sources of information.

We report results from four experiments that examined performance of an interceptive task that restricted movement of the hand and moving target to a horizontal plane. The task required accurate control over both where and when interception takes place. Three experiments studied the effects of four independent variables: target speed, target size, manipulandum size and movement amplitude. For small amplitude movements, small, fast targets were hit harder than larger slower ones and targets were hit harder with smaller manipulanda; movement time (MT) was unaffected by target size, but was shorter when the manipulandum was smaller. For larger amplitude movements, smaller, faster targets were also hit harder, but MTs tended to be greater when targets were smaller. The results support the idea that MT and peak movement speed can be independently controlled to some degree in order to meet the accuracy demands of the task. Analysis of the task showed that spatial and temporal accuracy demands are interdependent, indicating that the spatial and temporal variable errors should covary such that increases in one are accompanied by decreases in the other. This can be tested if there is no variation in interception location; which was not the case in the first three experiments. In a final experiment variation in interception location was restricted by requiring that the target be struck through an aperture. Both spatial and temporal variable errors could be estimated. As predicted, it was found that when spatial errors were small, temporal errors were large.

Resumo Estudos têm sido realizados para explicar a relação entre os níveis de ansiedade eo desempenho esportivo. O presente estudo teve como objetivos investigar quais são os momentos de maior ansiedade em uma competição de tênis de mesa, como os atletas a controlam, e se há diferença entre meninos e meninas. Após o último jogo em uma competição, 36 mesatenistas mirins responderam a um questionário sobre suas ansiedades.

RESUMO O objetivo desse estudo foi investigar o desempenho em uma tarefa complexa de “timing” coincidente em função da idade e da velocidade do estímulo visual. Os participantes foram 58 adultos voluntários de ambos os sexos (38 adultos jovens com idades entre 19 e 23 anos e 20 adultos maduros com idades entre 35 e 50 anos). Cada grupo de adultos foi dividido em três subgrupos de acordo com uma velocidade do estímulo visual (lenta, moderada e rápida).