title: Aperture extent and stimulus speed affect the perception of visual acceleration.
abstract: Humans are generally poor at detecting the presence of visual acceleration, but it is unclear whether the extent of a field of moving objects through an aperture affects this ability. Hypothetically, the farther a stimulus can accelerate uninterrupted by an aperture's physical constraints, the easier it should be to discern its motion profile. We varied the horizontal extent of the aperture through which continuously accelerating or decelerating random dot arrays were presented at different average speeds, and measured acceleration and deceleration detection thresholds. We also hypothesized that manipulating aperture extent at different speeds would change how observers visually pursue acceleration, which we tested in a control experiment. Results showed that, while there was no difference between the acceleration and deceleration conditions, detection was better in the larger than small aperture conditions. Regardless of aperture size, smaller acceleration and deceleration rates (relative to average speed) were needed to detect changing speed in faster than slower speed ranges. Similarly, observers tracked the stimuli to a greater extent in the larger than small apertures, and smooth pursuit was overall poorer at faster than slower speeds. Notably, the effect of speed on pursuit was greater for the larger than small aperture conditions, suggesting that the small aperture restricted pursuit. Furthermore, there was little difference in psychophysical and eye movement data between the medium and large aperture conditions within each speed range, indicating that it is easier to detect an accelerating profile when the aperture is large enough to encourage a minimum level of pursuit.
authors.affiliation: Psychology Department, University of Western Ontario, London, ON, N6A 5C2, Canada. amuelle4@alumni.uwo.ca.|Center for ADHD, Division of Behavioral Medicine and Clinical Psychology, Cincinnati Children's Hospital Medical Center, 3333 Burnet Ave., ML-10006, Cincinnati, OH, 45229-3039, USA. amuelle4@alumni.uwo.ca.
authors.forename: Alexandra S
authors.initials: AS
authors.lastname: Mueller
authors.affiliation: Vision Science Research Program, Toronto Western Hospital, Toronto, ON, M5T 2S8, Canada.|Department of Ophthalmology and Vision Sciences, University of Toronto, Toronto, ON, M5T 2S8, Canada.|Centre for Vision Research, York University, Toronto, ON, M3J 1P3, Canada.
authors.forename: Esther G
authors.initials: EG
authors.lastname: González
authors.affiliation: Psychology Department, University at Buffalo, The State University of New York, Buffalo, NY, 14260-4110, USA.
authors.forename: Chris
authors.initials: C
authors.lastname: McNorgan
authors.affiliation: Vision Science Research Program, Toronto Western Hospital, Toronto, ON, M5T 2S8, Canada.|Department of Ophthalmology and Vision Sciences, University of Toronto, Toronto, ON, M5T 2S8, Canada.|Centre for Vision Research, York University, Toronto, ON, M3J 1P3, Canada.
authors.forename: Martin J
authors.initials: MJ
authors.lastname: Steinbach
authors.affiliation: Psychology Department, University of Western Ontario, London, ON, N6A 5C2, Canada.
authors.forename: Brian
authors.initials: B
authors.lastname: Timney
mesh_terms: D000054:Acceleration; D000328:Adult; D016009:Chi-Square Distribution; D004192:Discrimination, Psychological / Q000502:physiology*; D005133:Eye Movements / Q000502:physiology*; D005139:Eyeglasses; D005260:Female; D006801:Humans; D008297:Male; D009039:Motion Perception / Q000502:physiology*; D010775:Photic Stimulation; D011601:Psychophysics; D014794:Visual Fields / Q000502:physiology*; D055815:Young Adult
keywords: Acceleration perception; Aperture; Deceleration perception; Smooth pursuit; Speed