June 2007
Volume 7, Issue 9
Free
Vision Sciences Society Annual Meeting Abstract  |   June 2007
Size judgments of looming targets: Effect of speed, location and the utilization of eye movements
Author Affiliations
  • Raiju Babu
    University of Waterloo
  • Susan Leat
    University of Waterloo
  • Elizabeth Irving
    University of Waterloo
Journal of Vision June 2007, Vol.7, 848. doi:10.1167/7.9.848
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      Raiju Babu, Susan Leat, Elizabeth Irving; Size judgments of looming targets: Effect of speed, location and the utilization of eye movements. Journal of Vision 2007;7(9):848. doi: 10.1167/7.9.848.

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      © ARVO (1962-2015); The Authors (2016-present)

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Abstract

Purpose: Judging the size of looming objects is important in many daily activities including driving and sports. The aim of the current experiment was to investigate the effect of speed, location, and the use of eye movements, in judging the size of looming targets.

Methods: Ten participants (mean age 27.7 ±4) observed a looming target (a vertical bar that appears to come towards the observer) projected on a screen, at a distance of 2m. Participants clicked a button when the size of the looming target matched a previously shown target. Responses for looming targets at five speeds were obtained in random order from one of the following: a central location (0 deg), a series of peripheral locations (−20,−10, 10 and 20 degrees) while fixating a central location or the same peripheral locations but with eye movements toward the looming targets. Eye movements were recorded with a video-based eye tracker. The effect of speed, target location and the use of eye movements on size match estimates was determined using a mixed design four factor ANOVA. A Tukey's post hoc was used for pair-wise comparisons.

Results: Higher speeds resulted in larger size match estimates for all target locations (F[4,4935]=20.73; p[[lt]]0.01).The slope of subjects responses (in size) was significantly different from the rate of stimulus change. A size match main effect was found between central and peripheral locations both with and without eye movements (F[4,4935]=25.23; p[[lt]]0.01).The interaction between target location and speed was not significant (F[8,5485]=0.19; p[[gt]]0.05).

Conclusions: Looming speed and target location affect the ability to estimate the size of objects. Size judgments are generally seen to be overestimated but not with a constant reaction time. Location differences in responses cannot be explained by the differences in retinal motion cues as similar results were obtained with eye movements.

Babu, R. Leat, S. Irving, E. (2007). Size judgments of looming targets: Effect of speed, location and the utilization of eye movements [Abstract]. Journal of Vision, 7(9):848, 848a, http://journalofvision.org/7/9/848/, doi:10.1167/7.9.848. [CrossRef]
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