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Jing Chen, Matteo Valsecchi, Karl Gegenfurtner; Anticipatory smooth pursuit of intentional finger movement. Journal of Vision 2015;15(12):1017. doi: 10.1167/15.12.1017.
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The smooth pursuit system is known to have prediction mechanisms. In the present study we investigate whether the motor command for hand movements can be integrated in the prediction and used to anticipate pursuit. Some early studies have found that ongoing pursuit is more accurate and has fewer catch-up saccades when self-generated motion is tracked (e.g., Steinbach & Held, 1968). However, it is not clear whether anticipatory smooth pursuit can be observed before the hand motion starts. Five Observers were asked to place their index finger on a flat screen and to fixate it. They could freely decide to move their finger to the left or to the right as soon as an auditory signal was presented. They were asked to pursue the finger with their gaze. Both gaze and finger positions were recorded. In two control conditions observers tracked a finger-sized dot on the screen. The dot motions were the replays of each observer's own finger movements. In one condition the motion direction was predictable, in the other it changed randomly between trials. When tracking the finger, the eye started to move on average 30 ms before finger motion. In 76% of all trials the eye started before the finger. In the predictable motion condition, pursuit latency was 24 ms on average, indicating an effect of anticipation compared to a latency of 104 ms in the unpredictable condition. In addition, the finger tracking condition showed significantly fewer catch-up saccades (~2 s-1) than the dot tracking conditions (3-4 s-1). This was particularly evident in the initiation period of pursuit. Overall, the present study shows that the oculomotor system is closely tied to body movements, leading to anticipatory pursuit and a more accurate tracking of the target.
Meeting abstract presented at VSS 2015
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