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Green RJ, Shahzad A, Fallah M. Gaze patterns during presentation of fixed and random phase radial frequency patterns. J Vis 2021; 21:2. [PMID: 34241621 PMCID: PMC8287044 DOI: 10.1167/jov.21.7.2] [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
Radial frequency (RF) patterns, circles which have had their radius modulated as a function of their polar angle, have been used in the examination of the integration of contour information around closed contour patterns. Typically, these patterns have been presented in a random orientation from trial-to-trial in order to maintain spatial uncertainty as to the location of the deformation on the pattern, as it may affect observer strategy and performance. However, the effect of fixed and random orientation (phase) on observer gaze strategies used to discriminate RF patterns has not been directly tested. This study compared fixation patterns across four conditions: fixed phase single cycle; random phase single cycle; fixed phase three cycle; and random phase three cycle RF3 patterns. The results showed that observers fixated on the known location of deformation for the fixed phase single cycle condition but used a more central fixation for the other three conditions. This strategy had a significant effect on observer thresholds for the fixed phase single cycle condition, with greater adherence to the strategy resulting in lower thresholds. It was also found that for the single cycle patterns observers tended to fixate on different locations on the pattern: on the maximum orientation difference from circular for the fixed phase pattern; and on the point of maximum curvature for the random phase pattern. These differences in gaze patterns are likely driven by the underlying local or global processing of the fixed or random phase single cycle patterns, respectively.
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Affiliation(s)
- Robert J Green
- Centre for Vision Research, York University, Ontario, Canada.,Vision: Science to Applications, York University, Ontario, Canada.,
| | - Amal Shahzad
- School of Kinesiology and Health Science, York University, Ontario, Canada.,
| | - Mazyar Fallah
- Centre for Vision Research, York University, Ontario, Canada.,Vision: Science to Applications, York University, Ontario, Canada.,School of Kinesiology and Health Science, York University, Ontario, Canada.,
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Frequency ratio determines discrimination of concentric radial frequency patterns in the peripheral visual field. Atten Percept Psychophys 2020; 82:3993-4006. [PMID: 32888172 DOI: 10.3758/s13414-020-02001-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Using a radial frequency discrimination task that has not been tested in many previous studies, we examined the dependence of the pattern radius (4 to 16 deg) on the radial frequency thresholds of two different types of concentric radial frequency (RF) patterns: constant circular contour frequency (CCF) RF patterns with different radii, which have the constant physical length of modulation cycle in external real-world space, and constant radial frequency magnified RF patterns with different radii, which have the constant cortical length of modulation cycles. These two types RF patterns used as the reference stimuli had an equal maximum orientation difference from circularity regardless of change in radius. The discrimination threshold expressed by the frequency ratio between RF patterns of different frequencies vs. radius functions for the constant CCF RF patterns indicated different functional forms dependent on the modulation amplitude of the RF patterns. The thresholds increased with increasing pattern radius for small modulation amplitude RF patterns but were relatively flattened for large-amplitude RF patterns. This dependence was ascribed to the eccentricity effect wherein the deformation thresholds for discriminating the RF pattern from a circle increase with increasing stimulus eccentricity (Feng et al. 2020). The discrimination thresholds vs. radius functions for the magnified RF patterns were also flattened for different modulation amplitudes and frequencies. The thresholds (frequency ratio) were similar at all eccentricities. Cortical magnification neutralized the eccentricity effect observed for the constant CCF patterns.
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Feng Y, Wu Q, Yang J, Takahashi S, Ejima Y, Wu J, Zhang M. Eccentricity Effect of Deformation Detection for Radial Frequency Patterns With Their Centers at Fixation Point. Perception 2020; 49:858-881. [DOI: 10.1177/0301006620936473] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
We measured the eccentricity effect of deformation thresholds of circular contours for two types of the radial frequency (RF) patterns with their centers at the fixation point: constant circular contour frequency (CCF) RF patterns and constant RF magnified (retino-cortical scaling) RF patterns. We varied the eccentricity by changing the mean radius of the RF patterns while keeping the centers of the RF patterns at the fixation point. Our peripheral stimulus presentation was distinguished from previous studies which have simply translated RF patterns at different locations in the visual field. Sensitivity for such shape discrimination fell off as the moderate and high CCF patterns were presented on more eccentric sites but did not as the low CCF patterns. However, sensitivity held constant as the magnified RF patterns were presented on more eccentric sites, indicating that the eccentricity effects observed for the high and moderate CCF patterns were neutralized by retinocortical mapping. Notably, sensitivity for the magnified RF patterns with large radii (4°–16°) presented in the peripheral field revealed a similar RF dependence observed for RF patterns with small radii (0.25°–1.0°) presented at the fovea in previous studies.
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Affiliation(s)
- Yang Feng
- Biomedical Engineering Laboratory, Graduate School of Natural Science and Technology, Okayama University, Japan
| | - Qiong Wu
- Department of Psychology, Suzhou University of Science and Technology, China; Cognitive Neuroscience Laboratory, Graduate School of Interdisciplinary Science and Engineering in Health Systems, Okayama University, Japan
| | | | | | - Yoshimichi Ejima
- Cognitive Neuroscience Laboratory, Graduate School of Interdisciplinary Science and Engineering in Health Systems, Okayama University, Japan
| | - Jinglong Wu
- Key Laboratory of Biomimetic Robots and System, Ministry of Education, State Key Laboratory of Intelligent Control and Decision of Complex Systems, Beijing Institute of Technology, China; Cognitive Neuroscience Laboratory, Graduate School of Interdisciplinary Science and Engineering in Health Systems, Okayama University, Japan
| | - Ming Zhang
- Department of Psychology, Suzhou University of Science and Technology, China; Cognitive Neuroscience Laboratory, Graduate School of Interdisciplinary Science and Engineering in Health Systems, Okayama University, Japan; Department of Psychology, Soochow University, China
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Gheorghiu E, Dering BR. Shape facilitates number: brain potentials and microstates reveal the interplay between shape and numerosity in human vision. Sci Rep 2020; 10:12413. [PMID: 32709892 PMCID: PMC7381628 DOI: 10.1038/s41598-020-68788-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2020] [Accepted: 06/19/2020] [Indexed: 12/04/2022] Open
Abstract
Recognition of simple shapes and numerosity estimation for small quantities are often studied independently of each other, but we know that these processes are both rapid and accurate, suggesting that they may be mediated by common neural mechanisms. Here we address this issue by examining how spatial configuration, shape complexity, and luminance polarity of elements affect numerosity estimation. We directly compared the Event Related Potential (ERP) time-course for numerosity estimation under shape and random configurations and found a larger N2 component for shape over lateral-occipital electrodes (250–400 ms), which also increased with higher numbers. We identified a Left Mid Frontal (LMF; 400–650 ms) component over left-lateralised medial frontal sites that specifically separated low and high numbers of elements, irrespective of their spatial configuration. Different luminance-polarities increased N2 amplitude only, suggesting that shape but not numerosity is selective to polarity. Functional microstates confined numerosity to a strict topographic distribution occurring within the LMF time-window, while a microstate responding only to shape-configuration was evidenced earlier, in the N2 time-window. We conclude that shape-coding precedes numerosity estimation, which can be improved when the number of elements and shape vertices are matched. Thus, numerosity estimation around the subitizing range is facilitated by a shape-template matching process.
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Affiliation(s)
- Elena Gheorghiu
- Department of Psychology, University of Stirling, Stirling, FK9 4LA, Scotland, UK.
| | - Benjamin R Dering
- Department of Psychology, University of Stirling, Stirling, FK9 4LA, Scotland, UK
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Wong VS, Dickinson JE, Badcock DR. Shape partitioning interacts with global shape integration. Vision Res 2020; 166:20-32. [DOI: 10.1016/j.visres.2019.11.005] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2019] [Revised: 11/11/2019] [Accepted: 11/18/2019] [Indexed: 11/29/2022]
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Green RJ, Dickinson JE, Badcock DR. Convergent evidence for global processing of shape. J Vis 2018; 18:7. [DOI: 10.1167/18.7.7] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Affiliation(s)
- Robert J. Green
- School of Psychological Science, The University of Western Australia, Perth, Australia
| | - J. Edwin Dickinson
- School of Psychological Science, The University of Western Australia, Perth, Australia
| | - David R. Badcock
- School of Psychological Science, The University of Western Australia, Perth, Australia
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Green RJ, Dickinson JE, Badcock DR. Integration of shape information occurs around closed contours but not across them. J Vis 2018; 18:6. [DOI: 10.1167/18.5.6] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Affiliation(s)
- Robert J. Green
- School of Psychological Science, The University of Western Australia, Perth, Australia
| | - J. Edwin Dickinson
- School of Psychological Science, The University of Western Australia, Perth, Australia
| | - David R. Badcock
- School of Psychological Science, The University of Western Australia, Perth, Australia
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Green RJ, Dickinson JE, Badcock DR. The effect of spatiotemporal displacement on the integration of shape information. J Vis 2018; 18:4. [DOI: 10.1167/18.5.4] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Affiliation(s)
- Robert J. Green
- School of Psychological Science, The University of Western Australia, Perth, Australia
| | - J. Edwin Dickinson
- School of Psychological Science, The University of Western Australia, Perth, Australia
| | - David R. Badcock
- School of Psychological Science, The University of Western Australia, Perth, Australia
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Almeida RA, Dickinson JE, Maybery MT, Badcock JC, Badcock DR. Visual search targeting either local or global perceptual processes differs as a function of autistic-like traits in the typically developing population. J Autism Dev Disord 2014; 43:1272-86. [PMID: 23054202 DOI: 10.1007/s10803-012-1669-7] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Relative to low scorers, high scorers on the autism-spectrum quotient (AQ) show enhanced performance on the embedded figures test and the radial frequency search task (RFST), which has been attributed to both enhanced local processing and differences in combining global percepts. We investigate the role of local and global processing further using the RFST in four experiments. High AQ adults maintained a consistent advantage in search speed across diverse target-distracter stimulus conditions. This advantage may reflect enhanced local processing of curvature in early stages of the form vision pathway and superior global detection of shape primitives. However, more probable is the presence of a superior search process that enables a consistent search advantage at both levels of processing.
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Affiliation(s)
- Renita A Almeida
- School of Psychology (M304), University of Western Australia, 35 Stirling Highway, Crawley, WA, 6009, Australia.
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Near their thresholds for detection, shapes are discriminated by the angular separation of their corners. PLoS One 2013; 8:e66015. [PMID: 23741521 PMCID: PMC3669261 DOI: 10.1371/journal.pone.0066015] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2012] [Accepted: 05/06/2013] [Indexed: 11/19/2022] Open
Abstract
Observers make sense of scenes by parsing images on the retina into meaningful objects. This ability is retained for line drawings, demonstrating that critical information is concentrated at object boundaries. Information theoretic studies argue for further concentration at points of maximum curvature, or corners, on such boundaries [1]–[3] suggesting that the relative positions of such corners might be important in defining shape. In this study we use patterns subtly deformed from circular, by a sinusoidal modulation of radius, in order to measure threshold sensitivity to shape change. By examining the ability of observers to discriminate between patterns of different frequency and/or number of cycles of modulation in a 2x2 forced choice task we were able to show, psychophysically, that difference in a single cue, the periodicity of the corners (specifically the polar angle between two points of maximum curvature) was sufficient to allow discrimination of two patterns near their thresholds for detection. We conclude that patterns could be considered as labelled for this measure. These results suggest that a small number of such labels might be sufficient to identify an object.
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Schmidtmann G, Gordon GE, Bennett DM, Loffler G. Detecting shapes in noise: tuning characteristics of global shape mechanisms. Front Comput Neurosci 2013; 7:37. [PMID: 23720625 PMCID: PMC3655279 DOI: 10.3389/fncom.2013.00037] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2012] [Accepted: 04/02/2013] [Indexed: 11/13/2022] Open
Abstract
The proportion of signal elements embedded in noise needed to detect a signal is a standard tool for investigating motion perception. This paradigm was applied to the shape domain to determine how local information is pooled into a global percept. Stimulus arrays consisted of oriented Gabor elements that sampled the circumference of concentric radial frequency (RF) patterns. Individual Gabors were oriented tangentially to the shape (signal) or randomly (noise). In different conditions, signal elements were located randomly within the entire array or constrained to fall along one of the concentric contours. Coherence thresholds were measured for RF patterns with various frequencies (number of corners) and amplitudes (“sharpness” of corners). Coherence thresholds (about 10% = 15 elements) were lowest for circular shapes. Manipulating shape frequency or amplitude showed a range where thresholds remain unaffected (frequency ≤ RF4; amplitude ≤ 0.05). Increasing either parameter caused thresholds to rise. Compared to circles, thresholds increased by approximately four times for RF13 and five times for amplitudes of 0.3. Confining the signals to individual contours significantly reduced the number of elements needed to reach threshold (between 4 and 6), independent of the total number of elements on the contour or contour shape. Finally, adding external noise to the orientation of the elements had a greater effect on detection thresholds than adding noise to their position. These results provide evidence for a series of highly sensitive, shape-specific analysers which sum information globally but only from within specific annuli. These global mechanisms are tuned to position and orientation of local elements from which they pool information. The overall performance for arrays of elements can be explained by the sensitivity of multiple, independent concentric shape detectors rather than a single detector integrating information widely across space (e.g. Glass pattern detector).
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Bell J, Kanji J, Kingdom FA. Discrimination of rotated-in-depth curves is facilitated by stereoscopic cues, but curvature is not tuned for stereoscopic rotation-in-depth. Vision Res 2013. [DOI: 10.1016/j.visres.2012.11.003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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13
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Schmidtmann G, Kennedy GJ, Orbach HS, Loffler G. Non-linear global pooling in the discrimination of circular and non-circular shapes. Vision Res 2012; 62:44-56. [DOI: 10.1016/j.visres.2012.03.001] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2011] [Revised: 03/02/2012] [Accepted: 03/03/2012] [Indexed: 11/29/2022]
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Bell J, Gheorghiu E, Hess RF, Kingdom FAA. Global shape processing involves a hierarchy of integration stages. Vision Res 2011; 51:1760-6. [PMID: 21704056 DOI: 10.1016/j.visres.2011.06.003] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2011] [Revised: 04/20/2011] [Accepted: 06/02/2011] [Indexed: 10/18/2022]
Abstract
Radial Frequency (RF) patterns can be used to study the processing of familiar shapes, e.g. triangles and squares. Opinion is divided over whether the mechanisms that detect these shapes integrate local orientation and position information directly, or whether local orientations and positions are first combined to represent extended features, such as curves, and that it is local curvatures that the shape mechanism integrates. The latter view incorporates an intermediate processing stage, the former does not. To differentiate between these hypotheses we studied the processing of micro-patch sampled RF patterns as a function of the luminance polarity of successive elements on the contour path. Our first study measures shape after effects involving suprathreshold amplitude RF shapes and shows that alternating the luminance polarity of successive micro-patch elements disrupts adaptation of the global shape. Our second study shows that polarity alternations also disrupt sensitivity to threshold-amplitude RF patterns. These results suggest that neighbouring points of the contour shape are integrated into extended features by a polarity selective mechanism, prior to global shape processing, consistent with the view that for both threshold amplitude and suprathreshold amplitude patterns, global processing of RF shapes involves an intermediate stage of processing.
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Affiliation(s)
- Jason Bell
- McGill Vision Research, Dept. of Ophthalmology, McGill University, 687 Pine Av. West, H4-14, Montreal, Quebec, Canada H3A 1A1.
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Bell J, Hancock S, Kingdom FAA, Peirce JW. Global shape processing: which parts form the whole? J Vis 2010; 10:16. [PMID: 20884565 DOI: 10.1167/10.6.16] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Research suggests that detection of low-frequency radial frequency (RF) patterns involves global shape processing and that points of maximum curvature (corners) contribute more than points of minimum curvature (sides). However, this has only been tested with stimuli presented at the threshold of discriminability from a circle. We used RF pattern adaptation to (a) examine whether a supra-threshold RF pattern is processed as a global shape and (b) determine what the critical features are for representing its shape. We measured the perceived amplitude shift of an RF test pattern after prolonged exposure either to a higher amplitude pattern or to various combinations of its parts (concave maxima, convex maxima, inflections). We found greater shifts in perceived amplitude after adaptation to a "whole" pattern than after adaptation to its component parts, which alternated to produce equal net contrast. Furthermore, when adapting to specific parts of the shape in isolation, we found that each part generated a similar magnitude aftereffect. Although the whole is clearly greater than the sum of the parts, we find that concave maxima, convex maxima, and inflections contribute equally to global shape processing, a fact that is only apparent when using a supra-threshold appearance-based task.
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Affiliation(s)
- Jason Bell
- McGill Vision Research, Department of Ophthalmology, McGill University, Montreal, Quebec, Canada
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Bell J, Wilkinson F, Wilson HR, Loffler G, Badcock DR. Radial frequency adaptation reveals interacting contour shape channels. Vision Res 2009; 49:2306-17. [DOI: 10.1016/j.visres.2009.06.022] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2007] [Revised: 06/27/2009] [Accepted: 06/29/2009] [Indexed: 11/28/2022]
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Bell J, Kingdom FA. Global contour shapes are coded differently from their local components. Vision Res 2009; 49:1702-10. [DOI: 10.1016/j.visres.2009.04.012] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2008] [Revised: 03/25/2009] [Accepted: 04/09/2009] [Indexed: 10/20/2022]
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Bell J, Badcock DR. Narrow-band radial frequency shape channels revealed by sub-threshold summation. Vision Res 2009; 49:843-50. [DOI: 10.1016/j.visres.2009.03.001] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2007] [Revised: 03/03/2009] [Accepted: 03/03/2009] [Indexed: 10/21/2022]
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