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Abstract
It is widely believed that the human visual system is insensitive to acceleration in moving stimuli. This notion is supported by evidence that detection sensitivity for velocity modulation in moving stimuli is a lowpass function of the velocity modulation's temporal frequency. However, the lowpass function might be a mixture of detection by attention-based tracking and low-level mechanisms sensitive to acceleration. To revisit the issue of acceleration perception in relation to attentive tracking, we measured detection sensitivities for velocity modulations at various temporal frequencies (0.25–8 Hz) by using drifting gratings within long or short spatial windows that make the tracking of grating easier or more difficult respectively. Results showed that modulation sensitivity is lowpass for gratings with long windows but bandpass for gratings with short windows (peak at ~1 Hz). Moreover, we found that lowpass sensitivity becomes bandpass when we removed observer attention by a concurrent letter identification task. An additional visual-search experiment showed that a target dot moving with a velocity modulation at relatively high temporal frequencies (~2–4 Hz) was most easily detected among dots moving at various constant velocities. These results support the notion that high sensitivity to sluggish velocity modulation is a product of attentively tracking of moving stimuli and that the visual system is directly sensitive to accelerations and/or decelerations at the preattentive level.
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Affiliation(s)
- Ryohei Nakayama
- Department of Life Sciences, The University of TokyoTokyo, Japan
| | - Isamu Motoyoshi
- Department of Life Sciences, The University of TokyoTokyo, Japan
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Mueller AS, González EG, McNorgan C, Steinbach MJ, Timney B. Aperture extent and stimulus speed affect the perception of visual acceleration. Exp Brain Res 2016; 235:743-752. [PMID: 27866263 DOI: 10.1007/s00221-016-4824-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2016] [Accepted: 11/05/2016] [Indexed: 10/20/2022]
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.
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Affiliation(s)
- Alexandra S Mueller
- Psychology Department, University of Western Ontario, London, ON, N6A 5C2, Canada. .,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.
| | - Esther G González
- 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
| | - Chris McNorgan
- Psychology Department, University at Buffalo, The State University of New York, Buffalo, NY, 14260-4110, USA
| | - Martin J Steinbach
- 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
| | - Brian Timney
- Psychology Department, University of Western Ontario, London, ON, N6A 5C2, Canada
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