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UBC Theses and Dissertations

Accurate smooth pursuit eye movements lead to more accurate manual interceptions Fooken, Jolande

Abstract

In ball sports, athletes are taught to keep their eyes on the ball to catch or hit it successfully. This intuitive field experience has already been studied in the laboratory, indicating that tracking a moving object with smooth pursuit eye movements enhances our ability to predict the object’s trajectory in time and space. Similarly, intercepting a moving object critically relies on motion prediction. Here we assessed the functional significance of eye movements for manual interceptions. In a novel paradigm, we asked observers (n=32) to track a small moving dot, backprojected onto a translucent screen, and to intercept it with their index finger in a designated ‘hit zone’. Hereby, only the first part (100-300 ms) of the trajectory was shown. Thus, observers had to extrapolate the trajectory and intercept its assumed position anywhere within the hit zone. Results show that better pursuit (low eye position and velocity error, high velocity gain, few catch-up saccades of small amplitude) lead to more accurate interceptions. A Hazard analysis yielded two interception strategies: Early interceptors relied on tracking quality and memory feedback given at the end of each trial, while late interceptors depended more on tracking smoothness, small initial saccades, and accurate eye latencies. Early interceptions (less time of invisibility) yielded smaller 2D interception error, while the interception timing was better for longer periods of smooth tracking (later interceptions). A regression model tree identified low tracking error and small saccadic eye movements as those eye parameters predicting accurate interceptions best. Not only do observers benefit from smooth pursuit eye movements during manual interception, but the interception accuracy also scales with the quality of the eye movements.

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Attribution-NonCommercial-NoDerivs 2.5 Canada

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