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Boswell AM, Kohler PJ, McCarthy JD, Caplovitz GP. Perceived group size is determined by the centroids of the component elements. J Vis 2021; 21:1. [PMID: 34851391 PMCID: PMC8648053 DOI: 10.1167/jov.21.13.1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
To accomplish the deceptively simple task of perceiving the size of objects in the visual scene, the visual system combines information about the retinal size of the object with several other cues, including perceived distance, relative size, and prior knowledge. When local component elements are perceptually grouped to form objects, the task is further complicated because a grouped object does not have a continuous contour from which retinal size can be estimated. Here, we investigate how the visual system solves this problem and makes it possible for observers to judge the size of perceptually grouped objects. We systematically vary the shape and orientation of the component elements in a two-alternative forced-choice task and find that the perceived size of the array of component objects can be almost perfectly predicted from the distance between the centroids of the component elements and the center of the array. This is true whether the global contour forms a circle or a square. When elements were positioned such that the centroids along the global contour were at different distances from the center, perceived size was based on the average distance. These results indicate that perceived size does not depend on the size of individual elements, and that smooth contours formed by the outer edges of the component elements are not used to estimate size. The current study adds to a growing literature highlighting the importance of centroids in visual perception and may have implications for how size is estimated for ensembles of different objects.
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Affiliation(s)
| | - Peter J Kohler
- Department of Psychology, York University, Toronto, Ontario, Canada.,Centre for Vision Research, York University, Toronto, Ontario, Canada.,
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Abstract
The accurate perception of human crowds is integral to social understanding and interaction. Previous studies have shown that observers are sensitive to several crowd characteristics such as average facial expression, gender, identity, joint attention, and heading direction. In two experiments, we examined ensemble perception of crowd speed using standard point-light walkers (PLW). Participants were asked to estimate the average speed of a crowd consisting of 12 figures moving at different speeds. In Experiment 1, trials of intact PLWs alternated with trials of scrambled PLWs with a viewing duration of 3 seconds. We found that ensemble processing of crowd speed could rely on local motion alone, although a globally intact configuration enhanced performance. In Experiment 2, observers estimated the average speed of intact-PLW crowds that were displayed at reduced viewing durations across five blocks of trials (between 2500 ms and 500 ms). Estimation of fast crowds was precise and accurate regardless of viewing duration, and we estimated that three to four walkers could still be integrated at 500 ms. For slow crowds, we found a systematic deterioration in performance as viewing time reduced, and performance at 500 ms could not be distinguished from a single-walker response strategy. Overall, our results suggest that rapid and accurate ensemble perception of crowd speed is possible, although sensitive to the precise speed range examined.
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Stoll S, Finlayson NJ, Schwarzkopf DS. Topographic signatures of global object perception in human visual cortex. Neuroimage 2020; 220:116926. [PMID: 32442640 PMCID: PMC7573540 DOI: 10.1016/j.neuroimage.2020.116926] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2019] [Revised: 04/20/2020] [Accepted: 05/07/2020] [Indexed: 01/12/2023] Open
Abstract
Our visual system readily groups dynamic fragmented input into global objects. How the brain represents global object perception remains however unclear. To address this question, we recorded brain responses using functional magnetic resonance imaging whilst observers viewed a dynamic bistable stimulus that could either be perceived globally (i.e., as a grouped and coherently moving shape) or locally (i.e., as ungrouped and incoherently moving elements). We further estimated population receptive fields and used these to back-project the brain activity measured during stimulus perception into visual space via a searchlight procedure. Global perception resulted in universal suppression of responses in lower visual cortex accompanied by wide-spread enhancement in higher object-sensitive cortex. However, follow-up experiments indicated that higher object-sensitive cortex is suppressed if global perception lacks shape grouping, and that grouping-related suppression can be diffusely confined to stimulated sites and accompanied by background enhancement once stimulus size is reduced. These results speak to a non-generic involvement of higher object-sensitive cortex in perceptual grouping and point to an enhancement-suppression mechanism mediating the perception of figure and ground. Lower visual cortex activity to grouped vs ungrouped dynamic stimuli is suppressed. When grouping a shape, activity in higher object-sensitive cortex is enhanced. Without shape grouping, activity in higher object-sensitive cortex is suppressed. Grouping-related suppression can be diffusely confined to stimulated cortical sites.
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Affiliation(s)
- Susanne Stoll
- Experimental Psychology, University College London, 26 Bedford Way, London, WC1H 0AP, UK.
| | - Nonie J Finlayson
- Experimental Psychology, University College London, 26 Bedford Way, London, WC1H 0AP, UK
| | - D Samuel Schwarzkopf
- Experimental Psychology, University College London, 26 Bedford Way, London, WC1H 0AP, UK
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Honma M, Itoi C, Midorikawa A, Terao Y, Masaoka Y, Kuroda T, Futamura A, Shiromaru A, Ohta H, Kato N, Kawamura M, Ono K. Contraction of distance and duration production in autism spectrum disorder. Sci Rep 2019; 9:8806. [PMID: 31217506 PMCID: PMC6584662 DOI: 10.1038/s41598-019-45250-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2018] [Accepted: 06/03/2019] [Indexed: 12/27/2022] Open
Abstract
Autism spectrum disorder (ASD) presents certain hallmark features associated with cognitive and social functions, however, the ability to estimate self-generated distance and duration in individuals with ASD are unclear. We compared the performance of 20 ASD individuals with 20 typical developments (TDs) with respect to two tasks: (1) the drawing of a line of a specified distance (10 or 20 cm) and (2) waiting for a specified time (10 or 20 s). We observed that both the line distances and waiting times were substantially shorter in the ASD group than in the TD group. Furthermore, a trait of "attention to detail," as measured by the Autism-Spectrum Quotient, correlated with some distance and duration productions observed in individuals with ASD. We suggest that attentional functions are related to the contraction of distance and duration in ASD.
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Affiliation(s)
- Motoyasu Honma
- Department of Physiology, Kyorin University School of Medicine, Tokyo, Japan.
| | - Chihiro Itoi
- Department of Psychology, Faculty of Letters, Chuo University, Tokyo, Japan
| | - Akira Midorikawa
- Department of Psychology, Faculty of Letters, Chuo University, Tokyo, Japan
| | - Yasuo Terao
- Department of Physiology, Kyorin University School of Medicine, Tokyo, Japan
| | - Yuri Masaoka
- Department of Physiology, Showa University School of Medicine, Tokyo, Japan
| | - Takeshi Kuroda
- Division of Neurology, Department of Medicine, Showa University School of Medicine, Tokyo, Japan
| | - Akinori Futamura
- Division of Neurology, Department of Medicine, Showa University School of Medicine, Tokyo, Japan
| | - Azusa Shiromaru
- Division of Neurology, Department of Medicine, Showa University School of Medicine, Tokyo, Japan
| | - Haruhisa Ohta
- Medical Institute of Developmental Disabilities Research, Showa University, Tokyo, Japan
| | - Nobumasa Kato
- Medical Institute of Developmental Disabilities Research, Showa University, Tokyo, Japan
| | - Mitsuru Kawamura
- Division of Neurology, Department of Medicine, Showa University School of Medicine, Tokyo, Japan
| | - Kenjiro Ono
- Division of Neurology, Department of Medicine, Showa University School of Medicine, Tokyo, Japan.
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Erlikhman G, Caplovitz GP, Gurariy G, Medina J, Snow JC. Towards a unified perspective of object shape and motion processing in human dorsal cortex. Conscious Cogn 2018; 64:106-120. [PMID: 29779844 DOI: 10.1016/j.concog.2018.04.016] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2018] [Revised: 04/20/2018] [Accepted: 04/26/2018] [Indexed: 01/06/2023]
Abstract
Although object-related areas were discovered in human parietal cortex a decade ago, surprisingly little is known about the nature and purpose of these representations, and how they differ from those in the ventral processing stream. In this article, we review evidence for the unique contribution of object areas of dorsal cortex to three-dimensional (3-D) shape representation, the localization of objects in space, and in guiding reaching and grasping actions. We also highlight the role of dorsal cortex in form-motion interaction and spatiotemporal integration, possible functional relationships between 3-D shape and motion processing, and how these processes operate together in the service of supporting goal-directed actions with objects. Fundamental differences between the nature of object representations in the dorsal versus ventral processing streams are considered, with an emphasis on how and why dorsal cortex supports veridical (rather than invariant) representations of objects to guide goal-directed hand actions in dynamic visual environments.
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Affiliation(s)
| | | | - Gennadiy Gurariy
- Department of Psychology, University of Nevada, Reno, USA; Department of Psychology, University of Wisconsin, Milwaukee, USA
| | - Jared Medina
- Department of Psychological and Brain Sciences, University of Delaware, USA
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Yamamoto K, Miura K. Effect of motion coherence on time perception relates to perceived speed. Vision Res 2016; 123:56-62. [PMID: 26721584 DOI: 10.1016/j.visres.2015.11.004] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2015] [Revised: 11/03/2015] [Accepted: 11/05/2015] [Indexed: 11/25/2022]
Abstract
The present study examined the effect of coherence of moving visual objects on time perception. Participants observed stimuli composed of four line segments moving behind or in front of occluders. The line segments appeared to move either coherently as a diamond outline or incoherently, depending on the occlusion. Results from the temporal bisection task indicated that the duration of the coherently moving stimulus was perceived longer or shorter compared to the duration of the incoherently moving stimulus depending on the stimulus configurations. The speed comparison task revealed that the trend of the difference in perceived speed between the coherent and incoherent motions in each stimulus configuration was consistent with that of the difference in perceived duration between them. These results demonstrate the effect of motion coherence on perceived duration, and that this effect may be mediated by changes in perceived speed. Our finding provides evidence supporting the involvement of global motion processing in time perception.
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Affiliation(s)
- Kentaro Yamamoto
- Research Center for Advanced Science and Technology, The University of Tokyo, Tokyo, Japan; Faculty of Science and Engineering, Waseda University, Tokyo, Japan; Japan Society for the Promotion of Science, Japan.
| | - Kayo Miura
- Faculty of Human-Environment Studies, Kyushu University, Japan
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