1
|
Qian K. Examining the Impact of Human Face Stimulus on Shape-Contrast Effects during a Brief Presentation. Brain Sci 2022; 12:brainsci12070914. [PMID: 35884721 PMCID: PMC9313273 DOI: 10.3390/brainsci12070914] [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] [Received: 06/12/2022] [Revised: 07/09/2022] [Accepted: 07/11/2022] [Indexed: 11/26/2022] Open
Abstract
Shape-contrast effects have been introduced to the investigations into face perception with the aim of exploring face adaptation in the context of norm-based coding. Research has indicated that shape-contrast effects occur even for shapes as complex as the human face. However, whether the complexity of face stimuli alters the magnitude of shape-contrast effects needs to be examined. In this study, emoticons and realistic human faces were used with the original white circle as the test stimuli. The results revealed that the shape-contrast effect was dependent on the stimulus. However, there was no significant difference between the shape-contrast effect evoked by upright faces and that evoked by inverted ones. This suggests that the face stimuli influenced the strength of the shape-contrast effect: the mechanism of this effect involved multiple stages of the visual system related to luminance and complexity, rather than the holistic face perception.
Collapse
Affiliation(s)
- Kun Qian
- Institute for Asian and Oceanian Studies, Kyushu University, Fukuoka 819-0395, Japan
| |
Collapse
|
2
|
Adaptation in face animacy perception: An event-related potential study. Neuropsychologia 2021; 165:108118. [PMID: 34896405 DOI: 10.1016/j.neuropsychologia.2021.108118] [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: 11/02/2020] [Revised: 12/02/2021] [Accepted: 12/08/2021] [Indexed: 11/20/2022]
Abstract
A real face differs from an artificial face mainly in the animacy. Nowadays, the perception boundaries between the real and artificial faces are becoming blurred in our life with the ubiquitous use of AI. Therefore, the perception of animacy causes increasing interests. Here, we used an adaptation paradigm to investigate the animacy perception in faces. We morphed a real and an artificial face to generate a continuum of face images, and asked participants to judge the animacy of those face images after they were exposed to a real face or an artificial face. We found that after adaptation to a real face, the subjects were apt to identify a subsequently ambiguous face to be inanimate, whereas after adaptation to an artificial face, the subjects were apt to identify a subsequently ambiguous face to be animate, i.e., the face animacy aftereffect (FAAE). We simultaneously recorded EEG during the task and analyzed the event-related potentials in response to the test faces, and found that adaptation to a face animacy suppressed the amplitude of LPP (late positive potential) and prolonged the latencies of N250r and LPP, in response to subsequent animacy-congruent faces. However, for subsequent animacy-incongruent faces, the amplitude was enhanced in LPP and the latencies were shortened in N250r and LPP. Those modulations of N250r and LPP activity act as a neural correlate of face animacy adaptation.
Collapse
|
3
|
Thalamus exhibits less sensory variability quenching than cortex. Sci Rep 2019; 9:7590. [PMID: 31110242 PMCID: PMC6527544 DOI: 10.1038/s41598-019-43934-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2018] [Accepted: 05/03/2019] [Indexed: 12/20/2022] Open
Abstract
Spiking activity exhibits a large degree of variability across identical trials, which has been shown to be significantly reduced by stimulus onset in a wide range of cortical areas. Whether similar dynamics apply to the thalamus and in particular to the pulvinar is largely unknown. Here, we examined electrophysiological recordings from two adult rhesus macaques performing a perceptual task and comparatively investigated trial-to-trial variability in higher-order thalamus (ventral and dorsal pulvinar), the lateral geniculate nucleus (LGN) and visual cortex (area V4) prior to and following the presentation of a visual stimulus. We found spiking variability during stable fixation prior to stimulus onset to be considerably lower in both pulvinar and the LGN as compared to area V4. In contrast to the prominent variability reduction in V4 upon stimulus onset, variability in the thalamic nuclei was largely unaffected by visual stimulation. There was a small but significant variability decrease in the dorsal pulvinar, but not in the ventral portion of the pulvinar, which is closely connected to visual cortices and would thus have been expected to reflect cortical response properties. This dissociation did not stem from differences in response strength or mean firing rates and indicates fundamental differences in variability quenching between thalamus and cortex.
Collapse
|
4
|
Zeki S. Multiple asynchronous stimulus- and task-dependent hierarchies (STDH) within the visual brain's parallel processing systems. Eur J Neurosci 2016; 44:2515-2527. [DOI: 10.1111/ejn.13270] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2016] [Revised: 04/25/2016] [Accepted: 05/03/2016] [Indexed: 11/29/2022]
Affiliation(s)
- Semir Zeki
- Wellcome Laboratory of Neurobiology; University College London; London WC1E 6BT UK
| |
Collapse
|
5
|
Salmela VR, Henriksson L, Vanni S. Radial Frequency Analysis of Contour Shapes in the Visual Cortex. PLoS Comput Biol 2016; 12:e1004719. [PMID: 26866917 PMCID: PMC4750910 DOI: 10.1371/journal.pcbi.1004719] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2015] [Accepted: 12/17/2015] [Indexed: 12/18/2022] Open
Abstract
Cumulative psychophysical evidence suggests that the shape of closed contours is analysed by means of their radial frequency components (RFC). However, neurophysiological evidence for RFC-based representations is still missing. We investigated the representation of radial frequency in the human visual cortex with functional magnetic resonance imaging. We parametrically varied the radial frequency, amplitude and local curvature of contour shapes. The stimuli evoked clear responses across visual areas in the univariate analysis, but the response magnitude did not depend on radial frequency or local curvature. Searchlight-based, multivariate representational similarity analysis revealed RFC specific response patterns in areas V2d, V3d, V3AB, and IPS0. Interestingly, RFC-specific representations were not found in hV4 or LO, traditionally associated with visual shape analysis. The modulation amplitude of the shapes did not affect the responses in any visual area. Local curvature, SF-spectrum and contrast energy related representations were found across visual areas but without similar specificity for visual area that was found for RFC. The results suggest that the radial frequency of a closed contour is one of the cortical shape analysis dimensions, represented in the early and mid-level visual areas.
Collapse
Affiliation(s)
- Viljami R. Salmela
- Institute of Behavioural Sciences, Division of Cognitive and Neuropsychology, University of Helsinki, Helsinki, Finland
- Advanced Magnetic Imaging Centre, Aalto NeuroImaging, Aalto University School of Science, Espoo, Finland
- * E-mail:
| | - Linda Henriksson
- Advanced Magnetic Imaging Centre, Aalto NeuroImaging, Aalto University School of Science, Espoo, Finland
- Department of Neuroscience and Biomedical Engineering, Aalto University, Espoo, Finland
| | - Simo Vanni
- Advanced Magnetic Imaging Centre, Aalto NeuroImaging, Aalto University School of Science, Espoo, Finland
- Clinical Neurosciences, Neurology, University of Helsinki and Helsinki University Hospital, Helsinki, Finland
| |
Collapse
|
6
|
Processing convexity and concavity along a 2-D contour: figure-ground, structural shape, and attention. Psychon Bull Rev 2013. [PMID: 23188740 DOI: 10.3758/s13423-012-0347-2] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Interest in convexity has a long history in vision science. For smooth contours in an image, it is possible to code regions of positive (convex) and negative (concave) curvature, and this provides useful information about solid shape. We review a large body of evidence on the role of this information in perception of shape and in attention. This includes evidence from behavioral, neurophysiological, imaging, and developmental studies. A review is necessary to analyze the evidence on how convexity affects (1) separation between figure and ground, (2) part structure, and (3) attention allocation. Despite some broad agreement on the importance of convexity in these areas, there is a lack of consensus on the interpretation of specific claims--for example, on the contribution of convexity to metric depth and on the automatic directing of attention to convexities or to concavities. The focus is on convexity and concavity along a 2-D contour, not convexity and concavity in 3-D, but the important link between the two is discussed. We conclude that there is good evidence for the role of convexity information in figure-ground organization and in parsing, but other, more specific claims are not (yet) well supported.
Collapse
|
7
|
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]
|
8
|
Abstract
Successful use of rodents as models for studying object vision crucially depends on the ability of their visual system to construct representations of visual objects that tolerate (i.e., remain relatively unchanged with respect to) the tremendous changes in object appearance produced, for instance, by size and viewpoint variation. Whether this is the case is still controversial, despite some recent demonstration of transformation-tolerant object recognition in rats. In fact, it remains unknown to what extent such a tolerant recognition has a spontaneous, perceptual basis, or, alternatively, mainly reflects learning of arbitrary associative relations among trained object appearances. In this study, we addressed this question by training rats to categorize a continuum of morph objects resulting from blending two object prototypes. The resulting psychometric curve (reporting the proportion of responses to one prototype along the morph line) served as a reference when, in a second phase of the experiment, either prototype was briefly presented as a prime, immediately before a test morph object. The resulting shift of the psychometric curve showed that recognition became biased toward the identity of the prime. Critically, this bias was observed also when the primes were transformed along a variety of dimensions (i.e., size, position, viewpoint, and their combination) that the animals had never experienced before. These results indicate that rats spontaneously perceive different views/appearances of an object as similar (i.e., as instances of the same object) and argue for the existence of neuronal substrates underlying formation of transformation-tolerant object representations in rats.
Collapse
|
9
|
Heron J, Aaen-Stockdale C, Hotchkiss J, Roach NW, McGraw PV, Whitaker D. Duration channels mediate human time perception. Proc Biol Sci 2011; 279:690-8. [PMID: 21831897 PMCID: PMC3248727 DOI: 10.1098/rspb.2011.1131] [Citation(s) in RCA: 83] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The task of deciding how long sensory events seem to last is one that the human nervous system appears to perform rapidly and, for sub-second intervals, seemingly without conscious effort. That these estimates can be performed within and between multiple sensory and motor domains suggest time perception forms one of the core, fundamental processes of our perception of the world around us. Given this significance, the current paucity in our understanding of how this process operates is surprising. One candidate mechanism for duration perception posits that duration may be mediated via a system of duration-selective ‘channels’, which are differentially activated depending on the match between afferent duration information and the channels' ‘preferred’ duration. However, this model awaits experimental validation. In the current study, we use the technique of sensory adaptation, and we present data that are well described by banks of duration channels that are limited in their bandwidth, sensory-specific, and appear to operate at a relatively early stage of visual and auditory sensory processing. Our results suggest that many of the computational principles the nervous system applies to coding visual spatial and auditory spectral information are common to its processing of temporal extent.
Collapse
Affiliation(s)
- James Heron
- Bradford School of Optometry and Vision Science, University of Bradford, Bradford BD7 1DP, UK.
| | | | | | | | | | | |
Collapse
|
10
|
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.
Collapse
Affiliation(s)
- Jason Bell
- McGill Vision Research, Dept. of Ophthalmology, McGill University, 687 Pine Av. West, H4-14, Montreal, Quebec, Canada H3A 1A1.
| | | | | | | |
Collapse
|
11
|
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.
Collapse
Affiliation(s)
- Jason Bell
- McGill Vision Research, Department of Ophthalmology, McGill University, Montreal, Quebec, Canada
| | | | | | | |
Collapse
|
12
|
What shape are the neural response functions underlying opponent coding in face space? A psychophysical investigation. Vision Res 2009; 50:300-14. [PMID: 19944116 DOI: 10.1016/j.visres.2009.11.016] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2009] [Revised: 11/17/2009] [Accepted: 11/22/2009] [Indexed: 11/23/2022]
Abstract
Recent evidence has shown that face space represents facial identity information using two-pool opponent coding. Here we ask whether the shape of the monotonic neural response functions underlying such coding is linear (i.e. face space codes all equal-sized physical changes with equal sensitivity) or nonlinear (e.g. face space shows greater coding sensitivity around the average face). Using adaptation aftereffects and pairwise discrimination tasks, our results for face attributes of eye height and mouth height demonstrate linear shape; including for bizarre faces far outside the normal range. We discuss how linear coding explains some results in the previous literature, including failures to find that adaptation enhances face discrimination, and suggest possible reasons why face space can maintain detailed coding of values far outside the normal range. We also discuss specific nonlinear coding models needed to explain other findings, and conclude face space appears to use a mixture of linear and nonlinear representations.
Collapse
|
13
|
Müller KM, Schillinger F, Do DH, Leopold DA. Dissociable perceptual effects of visual adaptation. PLoS One 2009; 4:e6183. [PMID: 19593384 PMCID: PMC2703777 DOI: 10.1371/journal.pone.0006183] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2009] [Accepted: 06/11/2009] [Indexed: 11/25/2022] Open
Abstract
Neurons in the visual cortex are responsive to the presentation of oriented and curved line segments, which are thought to act as primitives for the visual processing of shapes and objects. Prolonged adaptation to such stimuli gives rise to two related perceptual effects: a slow change in the appearance of the adapting stimulus (perceptual drift), and the distortion of subsequently presented test stimuli (adaptational aftereffects). Here we used a psychophysical nulling technique to dissociate and quantify these two classical observations in order to examine their underlying mechanisms and their relationship to one another. In agreement with previous work, we found that during adaptation horizontal and vertical straight lines serve as attractors for perceived orientation and curvature. However, the rate of perceptual drift for different stimuli was not predictive of the corresponding aftereffect magnitudes, indicating that the two perceptual effects are governed by distinct neural processes. Finally, the rate of perceptual drift for curved line segments did not depend on the spatial scale of the stimulus, suggesting that its mechanisms lie outside strictly retinotopic processing stages. These findings provide new evidence that the visual system relies on statistically salient intrinsic reference stimuli for the processing of visual patterns, and point to perceptual drift as an experimental window for studying the mechanisms of visual perception.
Collapse
Affiliation(s)
- Kai-Markus Müller
- Unit on Cognitive Neurophysiology and Imaging, Laboratory of Neuropsychology, National Institute of Mental Health, Bethesda, Maryland, United States of America
- International Max-Planck Research School, Tübingen, Germany
| | - Frieder Schillinger
- Unit on Cognitive Neurophysiology and Imaging, Laboratory of Neuropsychology, National Institute of Mental Health, Bethesda, Maryland, United States of America
- Department of Psychology, University of Tübingen, Tübingen, Germany
| | - David H. Do
- Unit on Cognitive Neurophysiology and Imaging, Laboratory of Neuropsychology, National Institute of Mental Health, Bethesda, Maryland, United States of America
- Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
| | - David A. Leopold
- Unit on Cognitive Neurophysiology and Imaging, Laboratory of Neuropsychology, National Institute of Mental Health, Bethesda, Maryland, United States of America
- * E-mail:
| |
Collapse
|