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Yoshiko Yabe, Melvyn Goodale; The intention to make a saccade distorts the timing of a Go/No-go signal presented at fixation. Journal of Vision 2014;14(10):1233. doi: 10.1167/14.10.1233.
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Research has shown that the intention to perform an action can distort one's perception of the timing of sensory events that occur after the action is initiated (Haggard et al., 2002; Kawabe et al., 2013). Here we show that, when participants are required to initiate a saccade, a distortion occurs in the perception of the timing of the 'go signal'. The saccadic trigger is perceived to have occurred later than it really did. This illusion also occurred on no-go trials in which the participant was instructed to maintain fixation. Participants viewed a black dot displayed on a computer screen. A hand rotated around the dot like a conventional clock. In a Go/No-go task, participants were asked to make a rapid eye movement towards a target that was presented 16° to the right of fixation if the 'clock' turned green and to not make a movement if the clock turned red. In the control condition, the participants saw the same changes in the colour of the clock presented at fixation while attending to the black target, but were never required to move their eyes. In both tasks, the participants were required to report, at the end of each trial, the location of the clock hand at the moment the clock changed colour. The ratio of the frequency of green vs. red trials was 7:3. The perceived position of the clock hand in the control task was not significantly different from the real timing of the colour change. In the go/no-go condition, there was a significant increase in the perceived timing of the colour change – even when participants did not move their eyes. This result suggests that the temporal distortion of the saccadic trigger is caused by the intention to make a saccade, not by the saccade itself.
Meeting abstract presented at VSS 2014
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