Peripheral duration estimation: No difference between saccade inhibition and execution
Tue-A6-Talk V-04
Presented by: Alina Krug
The duration of peripheral stimuli is underestimated compared to stimuli presented closer to fixation. In these studies participants were instructed to constantly direct their gaze on a central fixation cross. Yet, the presentation of peripheral stimuli elicits saccadic eye movements which which had to be inhibited. A number of studies show that the execution of saccadic eye movements during stimulus presentation shortens perceived duration. Further, the perceived timing of a stimulus that triggers a saccadic eye movement is distorted compared to the timing of a stimulus that is observed passively. In the present study we investigated how the execution compared to the inhibition of a saccadic eye movement towards a peripheral stimulus location affects its perceived duration. In a temporal bisection task, participants categorized black discs with varying duration (20-220 ms) presented in 6° or 12° of eccentricity as either short or long. Additionally, subjects were either instructed to fixate the screen center or perform saccades to the peripheral stimulus location in a block-wise manner with blocks counterbalanced between participants. The effect of eccentricity was replicated: Stimuli at 12° were perceived as shorter compared to stimuli at 6°. Overall, saccade inhibition versus saccade execution did not differentially affect duration estimation. Except when considering block order: Descriptively, the eccentricity effect was larger in the saccade condition when the saccade condition was performed after the fixation condition. No effect of block order was found when the saccade condition was performed first. We discuss the results in the context of reference effects.
Keywords: duration estimation, time perception, eye movements