1
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Hafri A, Green EJ, Firestone C. Compositionality in visual perception. Behav Brain Sci 2023; 46:e277. [PMID: 37766604 DOI: 10.1017/s0140525x23001838] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/29/2023]
Abstract
Quilty-Dunn et al.'s wide-ranging defense of the Language of Thought Hypothesis (LoTH) argues that vision traffics in abstract, structured representational formats. We agree: Vision, like language, is compositional - just as words compose into phrases, many visual representations contain discrete constituents that combine in systematic ways. Here, we amass evidence extending this proposal, and explore its implications for how vision interfaces with the rest of the mind.
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Affiliation(s)
- Alon Hafri
- Department of Linguistics and Cognitive Science, University of Delaware, Newark, DE, USA. ; https://pal.lingcogsci.udel.edu/
| | - E J Green
- Department of Linguistics and Philosophy, Massachusetts Institute of Technology, Cambridge, MA, USA. ; https://sites.google.com/site/greenedwinj/
| | - Chaz Firestone
- Department of Psychological and Brain Sciences, Johns Hopkins University, Baltimore, MD, USA. ; https://perception.jhu.edu/
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2
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Vannuscorps G, Galaburda A, Caramazza A. From intermediate shape-centered representations to the perception of oriented shapes: response to commentaries. Cogn Neuropsychol 2023; 40:71-94. [PMID: 37642330 DOI: 10.1080/02643294.2023.2250511] [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: 04/19/2023] [Revised: 07/14/2023] [Accepted: 07/31/2023] [Indexed: 08/31/2023]
Abstract
In this response paper, we start by addressing the main points made by the commentators on the target article's main theoretical conclusions: the existence and characteristics of the intermediate shape-centered representations (ISCRs) in the visual system, their emergence from edge detection mechanisms operating on different types of visual properties, and how they are eventually reunited in higher order frames of reference underlying conscious visual perception. We also address the much-commented issue of the possible neural mechanisms of the ISCRs. In the final section, we address more specific and general comments, questions, and suggestions which, albeit very interesting, were less directly focused on the main conclusions of the target paper.
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Affiliation(s)
- Gilles Vannuscorps
- Department of Psychology, Harvard University, Cambridge, MA, USA
- Institute of Psychological Sciences, Université catholique de Louvain, Louvain-la-Neuve, Belgium
- Institute of Neuroscience, Université catholique de Louvain, Louvain-la-Neuve, Belgium
- Louvain Bionics, Université catholique de Louvain, Louvain-la-Neuve, Belgium
| | - Albert Galaburda
- Department of Neurology, Harvard Medical School and Beth Israel Deaconess Medical Center, Boston, MA, USA
| | - Alfonso Caramazza
- Department of Psychology, Harvard University, Cambridge, MA, USA
- Center for Mind/Brain Sciences (CIMeC), Università degli Studi di Trento, Rovereto, Italy
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3
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Ayzenberg V, Behrmann M. Does the brain's ventral visual pathway compute object shape? Trends Cogn Sci 2022; 26:1119-1132. [PMID: 36272937 DOI: 10.1016/j.tics.2022.09.019] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2022] [Revised: 09/22/2022] [Accepted: 09/26/2022] [Indexed: 11/11/2022]
Abstract
A rich behavioral literature has shown that human object recognition is supported by a representation of shape that is tolerant to variations in an object's appearance. Such 'global' shape representations are achieved by describing objects via the spatial arrangement of their local features, or structure, rather than by the appearance of the features themselves. However, accumulating evidence suggests that the ventral visual pathway - the primary substrate underlying object recognition - may not represent global shape. Instead, ventral representations may be better described as a basis set of local image features. We suggest that this evidence forces a reevaluation of the role of the ventral pathway in object perception and posits a broader network for shape perception that encompasses contributions from the dorsal pathway.
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Affiliation(s)
- Vladislav Ayzenberg
- Neuroscience Institute, Carnegie Mellon University, Pittsburgh, PA 15213, USA; Psychology Department, Carnegie Mellon University, Pittsburgh, PA 15213, USA.
| | - Marlene Behrmann
- Neuroscience Institute, Carnegie Mellon University, Pittsburgh, PA 15213, USA; Psychology Department, Carnegie Mellon University, Pittsburgh, PA 15213, USA; The Department of Ophthalmology, University of Pittsburgh, Pittsburgh, PA 15260, USA.
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4
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Ayzenberg V, Lourenco S. Perception of an object's global shape is best described by a model of skeletal structure in human infants. eLife 2022; 11:e74943. [PMID: 35612898 PMCID: PMC9132572 DOI: 10.7554/elife.74943] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2021] [Accepted: 05/09/2022] [Indexed: 11/13/2022] Open
Abstract
Categorization of everyday objects requires that humans form representations of shape that are tolerant to variations among exemplars. Yet, how such invariant shape representations develop remains poorly understood. By comparing human infants (6-12 months; N=82) to computational models of vision using comparable procedures, we shed light on the origins and mechanisms underlying object perception. Following habituation to a never-before-seen object, infants classified other novel objects across variations in their component parts. Comparisons to several computational models of vision, including models of high-level and low-level vision, revealed that infants' performance was best described by a model of shape based on the skeletal structure. Interestingly, infants outperformed a range of artificial neural network models, selected for their massive object experience and biological plausibility, under the same conditions. Altogether, these findings suggest that robust representations of shape can be formed with little language or object experience by relying on the perceptually invariant skeletal structure.
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Affiliation(s)
| | - Stella Lourenco
- Department of Psychology, Emory UniversityAtlantaUnited States
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5
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Konkle T, Alvarez GA. A self-supervised domain-general learning framework for human ventral stream representation. Nat Commun 2022; 13:491. [PMID: 35078981 PMCID: PMC8789817 DOI: 10.1038/s41467-022-28091-4] [Citation(s) in RCA: 28] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2021] [Accepted: 12/13/2021] [Indexed: 12/25/2022] Open
Abstract
Anterior regions of the ventral visual stream encode substantial information about object categories. Are top-down category-level forces critical for arriving at this representation, or can this representation be formed purely through domain-general learning of natural image structure? Here we present a fully self-supervised model which learns to represent individual images, rather than categories, such that views of the same image are embedded nearby in a low-dimensional feature space, distinctly from other recently encountered views. We find that category information implicitly emerges in the local similarity structure of this feature space. Further, these models learn hierarchical features which capture the structure of brain responses across the human ventral visual stream, on par with category-supervised models. These results provide computational support for a domain-general framework guiding the formation of visual representation, where the proximate goal is not explicitly about category information, but is instead to learn unique, compressed descriptions of the visual world.
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Affiliation(s)
- Talia Konkle
- Department of Psychology & Center for Brain Science, Harvard University, Cambridge, MA, USA.
| | - George A Alvarez
- Department of Psychology & Center for Brain Science, Harvard University, Cambridge, MA, USA.
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6
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Wilder J, Rezanejad M, Dickinson S, Siddiqi K, Jepson A, Walther DB. Neural correlates of local parallelism during naturalistic vision. PLoS One 2022; 17:e0260266. [PMID: 35061699 PMCID: PMC8782314 DOI: 10.1371/journal.pone.0260266] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2021] [Accepted: 11/07/2021] [Indexed: 11/18/2022] Open
Abstract
Human observers can rapidly perceive complex real-world scenes. Grouping visual elements into meaningful units is an integral part of this process. Yet, so far, the neural underpinnings of perceptual grouping have only been studied with simple lab stimuli. We here uncover the neural mechanisms of one important perceptual grouping cue, local parallelism. Using a new, image-computable algorithm for detecting local symmetry in line drawings and photographs, we manipulated the local parallelism content of real-world scenes. We decoded scene categories from patterns of brain activity obtained via functional magnetic resonance imaging (fMRI) in 38 human observers while they viewed the manipulated scenes. Decoding was significantly more accurate for scenes containing strong local parallelism compared to weak local parallelism in the parahippocampal place area (PPA), indicating a central role of parallelism in scene perception. To investigate the origin of the parallelism signal we performed a model-based fMRI analysis of the public BOLD5000 dataset, looking for voxels whose activation time course matches that of the locally parallel content of the 4916 photographs viewed by the participants in the experiment. We found a strong relationship with average local symmetry in visual areas V1-4, PPA, and retrosplenial cortex (RSC). Notably, the parallelism-related signal peaked first in V4, suggesting V4 as the site for extracting paralleism from the visual input. We conclude that local parallelism is a perceptual grouping cue that influences neuronal activity throughout the visual hierarchy, presumably starting at V4. Parallelism plays a key role in the representation of scene categories in PPA.
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Affiliation(s)
| | - Morteza Rezanejad
- University of Toronto, Toronto, Canada
- McGill University, Montreal, Canada
| | - Sven Dickinson
- University of Toronto, Toronto, Canada
- Samsung Toronto AI Research Center, Toronto, Canada
- Vector Institute, Toronto, Canada
| | | | - Allan Jepson
- University of Toronto, Toronto, Canada
- Samsung Toronto AI Research Center, Toronto, Canada
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7
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Ayzenberg V, Kamps FS, Dilks DD, Lourenco SF. Skeletal representations of shape in the human visual cortex. Neuropsychologia 2022; 164:108092. [PMID: 34801519 PMCID: PMC9840386 DOI: 10.1016/j.neuropsychologia.2021.108092] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2021] [Revised: 11/07/2021] [Accepted: 11/17/2021] [Indexed: 01/17/2023]
Abstract
Shape perception is crucial for object recognition. However, it remains unknown exactly how shape information is represented and used by the visual system. Here, we tested the hypothesis that the visual system represents object shape via a skeletal structure. Using functional magnetic resonance imaging (fMRI) and representational similarity analysis (RSA), we found that a model of skeletal similarity explained significant unique variance in the response profiles of V3 and LO. Moreover, the skeletal model remained predictive in these regions even when controlling for other models of visual similarity that approximate low-to high-level visual features (i.e., Gabor-jet, GIST, HMAX, and AlexNet), and across different surface forms, a manipulation that altered object contours while preserving the underlying skeleton. Together, these findings shed light on shape processing in human vision, as well as the computational properties of V3 and LO. We discuss how these regions may support two putative roles of shape skeletons: namely, perceptual organization and object recognition.
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Affiliation(s)
- Vladislav Ayzenberg
- Department of Psychology, Carnegie Mellon University, USA,Corresponding author: (V. Ayzenberg)
| | - Frederik S. Kamps
- Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, USA
| | | | - Stella F. Lourenco
- Department of Psychology, Emory University, USA,Corresponding author: (S.F. Lourenco)
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8
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Vannuscorps G, Galaburda A, Caramazza A. The form of reference frames in vision: The case of intermediate shape-centered representations. Neuropsychologia 2021; 162:108053. [PMID: 34624257 DOI: 10.1016/j.neuropsychologia.2021.108053] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2021] [Revised: 08/10/2021] [Accepted: 10/01/2021] [Indexed: 12/01/2022]
Abstract
Although a great deal is known about the early sensory and the later, perceptual, stages of visual processing, far less is known about the nature of intermediate representational units and reference frames. Progress in understanding intermediate levels of representations in vision is hindered by the complexity of interactions among multiple levels of representation in the visual system, making it difficult to isolate and study the nature of each particular level. Nature occasionally provides the opportunity to peer inside complex systems by isolating components of a system through accidental damage or genetic modification of neural components. We have recently reported the case of a young woman who perceives 2D bounded regions of space as if they were plane-rotated by 90, 180 or 270° around their center, mirrored across their own axes, or both. This suggested that an intermediate stage of processing consists in representing mutually exclusive 2D bounded regions extracted from the retinal image in their own "shape-centered" perceptual frame. We proposed to refer to this level of representation as "intermediate shape-centered representation" (ISCR). Here, we used Davida's pattern of errors across 9 experiments as a tool for specifying in greater detail the geometrical properties of the reference frame in which elongated and/or symmetrical shapes are represented at the level of the ISCR. The nature of Davida's errors in these experiments suggests that ISCRs are represented in reference frames composed of orthogonal axes aligned with and centered on the most elongated segment of elongated shapes and, for symmetrical shapes deprived of a straight segment, aligned with their axis of symmetry, and centered on their centroid.
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Affiliation(s)
- G Vannuscorps
- Department of Psychology, Harvard University, Cambridge, MA, 02138, USA; Institute of Psychological Sciences, Université Catholique de Louvain, 1348, Belgium; Institute of Neuroscience, Université Catholique de Louvain, 1348, Belgium; Louvain Bionics, Université Catholique de Louvain, 1348, Belgium.
| | - A Galaburda
- Department of Neurology, Harvard Medical School and Beth Israel Deaconess Medical Center, Boston, MA, 02215, USA
| | - A Caramazza
- Department of Psychology, Harvard University, Cambridge, MA, 02138, USA; Center for Mind/Brain Sciences (CIMeC), Università Degli Studi di Trento, Rovereto, 38068, Italy
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9
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Geometry of turbulent dissipation and the Navier-Stokes regularity problem. Sci Rep 2021; 11:8824. [PMID: 33893342 PMCID: PMC8065050 DOI: 10.1038/s41598-021-87774-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Accepted: 03/10/2021] [Indexed: 11/08/2022] Open
Abstract
The question of whether a singularity can form in an initially regular flow, described by the 3D incompressible Navier-Stokes (NS) equations, is a fundamental problem in mathematical physics. The NS regularity problem is super-critical, i.e., there is a 'scaling gap' between what can be established by mathematical analysis and what is needed to rule out a singularity. A recently introduced mathematical framework-based on a suitably defined 'scale of sparseness' of the regions of intense vorticity-brought the first scaling reduction of the NS super-criticality since the 1960s. Here, we put this framework to the first numerical test using a spatially highly resolved computational simulation performed near a 'burst' of the vorticity magnitude. The results confirm that the scale is well suited to detect the onset of dissipation and provide numerical evidence that ongoing mathematical efforts may succeed in closing the scaling gap.
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10
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Sakai K, Sakata Y, Kurematsu K. Interaction of surface pattern and contour shape in the tilt after effects evoked by symmetry. Sci Rep 2021; 11:8024. [PMID: 33850220 PMCID: PMC8044203 DOI: 10.1038/s41598-021-87429-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2020] [Accepted: 03/12/2021] [Indexed: 11/22/2022] Open
Abstract
Integration of multiple properties of an object is a fundamental function of the visual cortex in object recognition. For instance, surface patterns and contour shapes are thought to be crucial characteristics that jointly contribute to recognition. However, the mechanisms of integration and corresponding cortical representations have not been fully clarified. We investigated the integration of surfaces and shapes by examining the tilt after effects (TAEs) evoked by the symmetry of patterns and contours. As symmetry in both pattern and contour evokes TAEs, we can directly measure the interaction between the two. The measured TAEs exhibited mutual transfer between the symmetry of the pattern (SP) and that of the contour shape (SS), i.e., adaptation by SP (SS) evoked TAEs when tested by SS (SP), suggesting the existence of an integrated representation. Next, we examined the interaction between SP and SS when both were simultaneously presented in adaptation. Congruent adaptors wherein their symmetry axes aligned evoked compressive interaction, whereas incongruent adaptors wherein the axes of SP and SS tilted to the opposite directions evoked subtractive interaction. These results suggest the existence of a cortical representation that integrates the properties of the surface and shape with suppressive interactions, which can provide crucial insights into the formation of object representation as well as the integration of visual information in the cortex.
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Affiliation(s)
- Ko Sakai
- Computational Vision Science Laboratory, Department of Computer Science, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki, 305-8573, Japan.
| | - Yui Sakata
- Computational Vision Science Laboratory, Department of Computer Science, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki, 305-8573, Japan
| | - Ken Kurematsu
- Computational Vision Science Laboratory, Department of Computer Science, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki, 305-8573, Japan
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11
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Sasia B, Cacciamani L. High-definition transcranial direct current stimulation of the lateral occipital cortex influences figure-ground perception. Neuropsychologia 2021; 155:107792. [PMID: 33610616 DOI: 10.1016/j.neuropsychologia.2021.107792] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2020] [Revised: 01/11/2021] [Accepted: 02/14/2021] [Indexed: 01/28/2023]
Abstract
Prior work has shown that the lateral occipital cortex (LO) is involved in recognition of objects and their parts, as well as segregation of that object (or "figure") from its background. No studies, though, have examined how LO's functioning is influenced by non-invasive brain stimulation, particularly during a figure-ground perception task. The present study tested whether high-definition transcranial direct current stimulation (HD-tDCS) to right LO influences the effects of familiarity on figure-ground perception. Following 20 min of offline anodal stimulation (or sham), participants viewed masked stimuli consisting of two regions separated by a vertical border and were asked to report which region they perceived as figure. One region was the "critical" region, which either depicted a portion of a familiar object ("Familiar" stimuli), or a familiar object with its parts rearranged into a novel configuration ("Part-rearranged" stimuli). Previous research using these stimuli has found higher reports of the critical region as figure for Familiar vs. Part-rearranged displays, demonstrating the effect of familiarity on figure assignment. The results of the current study showed that HD-tDCS to right LO significantly influenced this typical behavioral pattern. Specifically, stimulation (vs. sham) increased reports of the critical region as figure for Part-rearranged stimuli, bringing perception of these displays up to the level of the Familiar stimuli. We interpret this finding as evidence that stimulation of right LO increased participants' reliance on the familiarity of the parts in their figure-ground judgements-a finding consistent with and extending previous research showing that LO is indeed sensitive to object parts. This is the first study showing that HD-tDCS to LO can influence the effects of familiarity on figure-ground perception.
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Affiliation(s)
- Brooke Sasia
- California Polytechnic State University, San Luis Obispo, CA, USA.
| | - Laura Cacciamani
- California Polytechnic State University, San Luis Obispo, CA, USA
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12
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Papale P, Leo A, Handjaras G, Cecchetti L, Pietrini P, Ricciardi E. Shape coding in occipito-temporal cortex relies on object silhouette, curvature, and medial axis. J Neurophysiol 2020; 124:1560-1570. [PMID: 33052726 DOI: 10.1152/jn.00212.2020] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Object recognition relies on different transformations of the retinal input, carried out by the visual system, that range from local contrast to object shape and category. While some of those transformations are thought to occur at specific stages of the visual hierarchy, the features they represent are correlated (e.g., object shape and identity) and selectivity for the same feature overlaps in many brain regions. This may be explained either by collinearity across representations or may instead reflect the coding of multiple dimensions by the same cortical population. Moreover, orthogonal and shared components may differently impact distinctive stages of the visual hierarchy. We recorded functional MRI activity while participants passively attended to object images and employed a statistical approach that partitioned orthogonal and shared object representations to reveal their relative impact on brain processing. Orthogonal shape representations (silhouette, curvature, and medial axis) independently explained distinct and overlapping clusters of selectivity in the occitotemporal and parietal cortex. Moreover, we show that the relevance of shared representations linearly increases moving from posterior to anterior regions. These results indicate that the visual cortex encodes shared relations between different features in a topographic fashion and that object shape is encoded along different dimensions, each representing orthogonal features.NEW & NOTEWORTHY There are several possible ways of characterizing the shape of an object. Which shape description better describes our brain responses while we passively perceive objects? Here, we employed three competing shape models to explain brain representations when viewing real objects. We found that object shape is encoded in a multidimensional fashion and thus defined by the interaction of multiple features.
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Affiliation(s)
- Paolo Papale
- Molecular Mind Laboratory, IMT School for Advanced Studies Lucca, Italy.,Department of Vision and Cognition, Netherlands Institute for Neuroscience, Amsterdam, The Netherlands
| | - Andrea Leo
- Molecular Mind Laboratory, IMT School for Advanced Studies Lucca, Italy.,Department of Translational Research and Advanced Technologies in Medicine and Surgery, University of Pisa, Pisa, Italy
| | - Giacomo Handjaras
- Molecular Mind Laboratory, IMT School for Advanced Studies Lucca, Italy
| | - Luca Cecchetti
- Molecular Mind Laboratory, IMT School for Advanced Studies Lucca, Italy
| | - Pietro Pietrini
- Molecular Mind Laboratory, IMT School for Advanced Studies Lucca, Italy
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13
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On the robustness of skeleton detection against adversarial attacks. Neural Netw 2020; 132:416-427. [DOI: 10.1016/j.neunet.2020.09.018] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2020] [Revised: 09/12/2020] [Accepted: 09/21/2020] [Indexed: 11/22/2022]
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14
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Kajal DS, Fioravanti C, Elshahabi A, Ruiz S, Sitaram R, Braun C. Involvement of top-down networks in the perception of facial emotions: A magnetoencephalographic investigation. Neuroimage 2020; 222:117075. [DOI: 10.1016/j.neuroimage.2020.117075] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2019] [Revised: 04/22/2020] [Accepted: 06/17/2020] [Indexed: 02/07/2023] Open
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15
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Hsu A, Lo YH, Ke SC, Lin L, Tseng P. Variation of picture angles and its effect on the Concealed Information Test. Cogn Res Princ Implic 2020; 5:33. [PMID: 32737640 PMCID: PMC7394988 DOI: 10.1186/s41235-020-00233-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2020] [Accepted: 05/28/2020] [Indexed: 12/03/2022] Open
Abstract
BACKGROUND The reaction time-based Concealed Information Test (RT-CIT) is a memory paradigm used to detect crime-related knowledge. However, this would also imply that the RT-CIT would be vulnerable to factors that are known to compromise object recognition or memory integrity. From this perspective, one key issue is whether "guilty" memory can be detected if the crime-related images are photographed at different angles from what the perpetrator saw, which is almost always the case in the field. To investigate this, here we manipulated the deviation angles, from 0° to 330° in 11 steps, between the study and test phases to assess how the RT-CIT holds up against angular rotations. RESULTS We observed a robust RT-CIT effect at all deviation angles for both deep-encoders (Experiment 1) and shallow-encoders (Experiment 2). The RT-CIT was effective within the first 250 or so trials for both encoding groups, with smaller probe-irrelevant differences beyond that. CONCLUSIONS With appropriate encoding and memory strength, RT-CIT images do not necessarily have to match the exact angle of the perpetrator's perspective at the time of the crime. Unnatural angles such as 90° and 270° or unconventional rotational axes may require caution. Trial number under 250 trials show maximal Probe-Irrelevant difference, but more trials may add power to improve detection accuracy.
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Affiliation(s)
- Ann Hsu
- Graduate Institute of Mind, Brain and Consciousness, Taipei Medical University, No.250, Wuxin St., Taipei City, 11031 Taiwan
| | - Yu-Hui Lo
- Graduate Institute of Mind, Brain and Consciousness, Taipei Medical University, No.250, Wuxin St., Taipei City, 11031 Taiwan
- Brain and Consciousness Research Center, Shuang Ho Hospital, Taipei Medical University, New Taipei City, Taiwan
| | - Shi-Chiang Ke
- Graduate Institute of Mind, Brain and Consciousness, Taipei Medical University, No.250, Wuxin St., Taipei City, 11031 Taiwan
| | - Lin Lin
- Graduate Institute of Mind, Brain and Consciousness, Taipei Medical University, No.250, Wuxin St., Taipei City, 11031 Taiwan
| | - Philip Tseng
- Graduate Institute of Mind, Brain and Consciousness, Taipei Medical University, No.250, Wuxin St., Taipei City, 11031 Taiwan
- Brain and Consciousness Research Center, Shuang Ho Hospital, Taipei Medical University, New Taipei City, Taiwan
- Psychiatric Research Center, Wan Fang Hospital, Taipei Medical University, Taipei, Taiwan
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16
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Ayzenberg V, Chen Y, Yousif SR, Lourenco SF. Skeletal representations of shape in human vision: Evidence for a pruned medial axis model. J Vis 2019; 19:6. [PMID: 31173631 PMCID: PMC6894409 DOI: 10.1167/19.6.6] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
A representation of shape that is low dimensional and stable across minor disruptions is critical for object recognition. Computer vision research suggests that such a representation can be supported by the medial axis-a computational model for extracting a shape's internal skeleton. However, few studies have shown evidence of medial axis processing in humans, and even fewer have examined how the medial axis is extracted in the presence of disruptive contours. Here, we tested whether human skeletal representations of shape reflect the medial axis transform (MAT), a computation sensitive to all available contours, or a pruned medial axis, which ignores contours that may be considered "noise." Across three experiments, participants (N = 2062) were shown complete, perturbed, or illusory two-dimensional shapes on a tablet computer and were asked to tap the shapes anywhere once. When directly compared with another viable model of shape perception (based on principal axes), participants' collective responses were better fit by the medial axis, and a direct test of boundary avoidance suggested that this result was not likely because of a task-specific cognitive strategy (Experiment 1). Moreover, participants' responses reflected a pruned computation in shapes with small or large internal or external perturbations (Experiment 2) and under conditions of illusory contours (Experiment 3). These findings extend previous work by suggesting that humans extract a relatively stable medial axis of shapes. A relatively stable skeletal representation, reflected by a pruned model, may be well equipped to support real-world shape perception and object recognition.
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Affiliation(s)
| | - Yunxiao Chen
- The London School of Economics and Political Science, London, UK
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17
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Visual noise consisting of X-junctions has only a minimal adverse effect on object recognition. Atten Percept Psychophys 2019; 82:995-1002. [PMID: 31728925 DOI: 10.3758/s13414-019-01840-2] [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
In 1968, Guzman showed that the myriad of surfaces composing a highly complex and novel assemblage of volumes can readily be assigned to their appropriate volumes in terms of the constraints offered by the vertices of coterminating edges. Of particular importance was the L-vertex, produced by the cotermination of two contours, which provides strong evidence for the termination of a 2-D surface. An X-junction, formed by the crossing of two contours without a change of direction at the crossing, played no role in the segmentation of a scene. If the potency of noise elements to affect recognition performance reflects their relevancy to the segmentation of scenes, as was suggested by Guzman, gaps in an object's contours bounded by irrelevant X-junctions would be expected to have little or no adverse effect on shape-based object recognition, whereas gaps bounded by L-junctions would be expected to have a strong deleterious effect when they disrupt the smooth continuation of contours. Guzman's roles for the various vertices and junctions have never been put to systematic test with respect to human object recognition. By adding identical noise contours to line drawings of objects that produced either L-vertices or X-junctions, these shape features could be compared with respect to their disruption of object recognition. Guzman's insights that irrelevant L-vertices should be highly disruptive and irrelevant X-vertices would have only a minimal deleterious effect were confirmed.
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Ayzenberg V, Lourenco SF. Skeletal descriptions of shape provide unique perceptual information for object recognition. Sci Rep 2019; 9:9359. [PMID: 31249321 PMCID: PMC6597715 DOI: 10.1038/s41598-019-45268-y] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2019] [Accepted: 05/29/2019] [Indexed: 11/17/2022] Open
Abstract
With seemingly little effort, humans can both identify an object across large changes in orientation and extend category membership to novel exemplars. Although researchers argue that object shape is crucial in these cases, there are open questions as to how shape is represented for object recognition. Here we tested whether the human visual system incorporates a three-dimensional skeletal descriptor of shape to determine an object's identity. Skeletal models not only provide a compact description of an object's global shape structure, but also provide a quantitative metric by which to compare the visual similarity between shapes. Our results showed that a model of skeletal similarity explained the greatest amount of variance in participants' object dissimilarity judgments when compared with other computational models of visual similarity (Experiment 1). Moreover, parametric changes to an object's skeleton led to proportional changes in perceived similarity, even when controlling for another model of structure (Experiment 2). Importantly, participants preferentially categorized objects by their skeletons across changes to local shape contours and non-accidental properties (Experiment 3). Our findings highlight the importance of skeletal structure in vision, not only as a shape descriptor, but also as a diagnostic cue of object identity.
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Papale P, Betta M, Handjaras G, Malfatti G, Cecchetti L, Rampinini A, Pietrini P, Ricciardi E, Turella L, Leo A. Common spatiotemporal processing of visual features shapes object representation. Sci Rep 2019; 9:7601. [PMID: 31110195 PMCID: PMC6527710 DOI: 10.1038/s41598-019-43956-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2018] [Accepted: 04/25/2019] [Indexed: 02/02/2023] Open
Abstract
Biological vision relies on representations of the physical world at different levels of complexity. Relevant features span from simple low-level properties, as contrast and spatial frequencies, to object-based attributes, as shape and category. However, how these features are integrated into coherent percepts is still debated. Moreover, these dimensions often share common biases: for instance, stimuli from the same category (e.g., tools) may have similar shapes. Here, using magnetoencephalography, we revealed the temporal dynamics of feature processing in human subjects attending to objects from six semantic categories. By employing Relative Weights Analysis, we mitigated collinearity between model-based descriptions of stimuli and showed that low-level properties (contrast and spatial frequencies), shape (medial-axis) and category are represented within the same spatial locations early in time: 100–150 ms after stimulus onset. This fast and overlapping processing may result from independent parallel computations, with categorical representation emerging later than the onset of low-level feature processing, yet before shape coding. Categorical information is represented both before and after shape, suggesting a role for this feature in the refinement of categorical matching.
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Affiliation(s)
- Paolo Papale
- Momilab, IMT School for Advanced Studies Lucca, 55100, Lucca, Italy
| | - Monica Betta
- Momilab, IMT School for Advanced Studies Lucca, 55100, Lucca, Italy
| | | | - Giulia Malfatti
- Center for Mind/Brain Sciences (CIMeC), University of Trento, 38068, Trento, Italy
| | - Luca Cecchetti
- Momilab, IMT School for Advanced Studies Lucca, 55100, Lucca, Italy
| | | | - Pietro Pietrini
- Momilab, IMT School for Advanced Studies Lucca, 55100, Lucca, Italy
| | | | - Luca Turella
- Center for Mind/Brain Sciences (CIMeC), University of Trento, 38068, Trento, Italy
| | - Andrea Leo
- Momilab, IMT School for Advanced Studies Lucca, 55100, Lucca, Italy.
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20
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Abstract
An intrinsic part of seeing objects is seeing how similar or different they are relative to one another. This experience requires that objects be mentally represented in a common format over which such comparisons can be carried out. What is that representational format? Objects could be compared in terms of their superficial features (e.g., degree of pixel-by-pixel overlap), but a more intriguing possibility is that they are compared on the basis of a deeper structure. One especially promising candidate that has enjoyed success in the computer vision literature is the shape skeleton-a geometric transformation that represents objects according to their inferred underlying organization. Despite several hints that shape skeletons are computed in human vision, it remains unclear how much they actually matter for subsequent performance. Here, we explore the possibility that shape skeletons help mediate the ability to extract visual similarity. Observers completed a same/different task in which two shapes could vary either in their skeletal structure (without changing superficial features such as size, orientation, and internal angular separation) or in large surface-level ways (without changing overall skeletal organization). Discrimination was better for skeletally dissimilar shapes: observers had difficulty appreciating even surprisingly large differences when those differences did not reorganize the underlying skeletons. This pattern also generalized beyond line drawings to 3-D volumes whose skeletons were less readily inferable from the shapes' visible contours. These results show how shape skeletons may influence the perception of similarity-and more generally, how they have important consequences for downstream visual processing.
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Wilder J, Rezanejad M, Dickinson S, Siddiqi K, Jepson A, Walther DB. Local contour symmetry facilitates scene categorization. Cognition 2018; 182:307-317. [PMID: 30415132 DOI: 10.1016/j.cognition.2018.09.014] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2018] [Revised: 09/20/2018] [Accepted: 09/22/2018] [Indexed: 10/27/2022]
Abstract
People are able to rapidly categorize briefly flashed images of real-world environments, even when they are reduced to line drawings. This setting allows for the study of time-limited perceptual grouping processes in the human visual system that are applicable to line drawings. Previous work (Wilder, Dickinson, Jepson, & Walther, 2018) showed that standard local features of individual contours, or junctions between contours, do not account for this rapid classification ability but, rather, the relative placement of these contours appeared to be important. Here we provide strong support for this observation by demonstrating that local ribbon symmetry between neighboring pairs of contours facilitates the categorization of complex real-world environments. To this end, we introduce a novel computational approach, based on the medial axis transform, for measuring the degree of local ribbon symmetry in a line drawing. We use this measure to separate the contour pixels for a given scene into the most ribbon symmetric half and the least ribbon symmetric half. We then show human observers the resulting half-images in a rapid-categorization experiment. Our results demonstrate that local ribbon symmetry facilitates the categorization of complex real-world environments. This is the first study of the role of local symmetry in inter-contour grouping for human scene classification. We conclude that local ribbon symmetry appears to play an important role in jump-starting the grouping of image content into meaningful units, even in flashed presentations.
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Papale P, Leo A, Cecchetti L, Handjaras G, Kay KN, Pietrini P, Ricciardi E. Foreground-Background Segmentation Revealed during Natural Image Viewing. eNeuro 2018; 5:ENEURO.0075-18.2018. [PMID: 29951579 PMCID: PMC6019392 DOI: 10.1523/eneuro.0075-18.2018] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2018] [Revised: 05/15/2018] [Accepted: 05/15/2018] [Indexed: 11/21/2022] Open
Abstract
One of the major challenges in visual neuroscience is represented by foreground-background segmentation. Data from nonhuman primates show that segmentation leads to two distinct, but associated processes: the enhancement of neural activity during figure processing (i.e., foreground enhancement) and the suppression of background-related activity (i.e., background suppression). To study foreground-background segmentation in ecological conditions, we introduce a novel method based on parametric modulation of low-level image properties followed by application of simple computational image-processing models. By correlating the outcome of this procedure with human fMRI activity, measured during passive viewing of 334 natural images, we produced easily interpretable "correlation images" from visual populations. Results show evidence of foreground enhancement in all tested regions, from V1 to lateral occipital complex (LOC), while background suppression occurs in V4 and LOC only. Correlation images derived from V4 and LOC revealed a preserved spatial resolution of foreground textures, indicating a richer representation of the salient part of natural images, rather than a simplistic model of object shape. Our results indicate that scene segmentation occurs during natural viewing, even when individuals are not required to perform any particular task.
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Affiliation(s)
- Paolo Papale
- Molecular Mind Lab, IMT School for Advanced Studies Lucca, Lucca, 55100 Italy
| | - Andrea Leo
- Molecular Mind Lab, IMT School for Advanced Studies Lucca, Lucca, 55100 Italy
| | - Luca Cecchetti
- Molecular Mind Lab, IMT School for Advanced Studies Lucca, Lucca, 55100 Italy
| | - Giacomo Handjaras
- Molecular Mind Lab, IMT School for Advanced Studies Lucca, Lucca, 55100 Italy
| | - Kendrick N. Kay
- Center for Magnetic Resonance Research, Department of Radiology, University of Minnesota, Twin Cities, Minneapolis, MN, 55455
| | - Pietro Pietrini
- Molecular Mind Lab, IMT School for Advanced Studies Lucca, Lucca, 55100 Italy
| | - Emiliano Ricciardi
- Molecular Mind Lab, IMT School for Advanced Studies Lucca, Lucca, 55100 Italy
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23
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An applet for the Gabor similarity scaling of the differences between complex stimuli. Atten Percept Psychophys 2017; 78:2298-2306. [PMID: 27557818 DOI: 10.3758/s13414-016-1191-7] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
It is widely accepted that after the first cortical visual area, V1, a series of stages achieves a representation of complex shapes, such as faces and objects, so that they can be understood and recognized. A major challenge for the study of complex shape perception has been the lack of a principled basis for scaling of the physical differences between stimuli so that their similarity can be specified, unconfounded by early-stage differences. Without the specification of such similarities, it is difficult to make sound inferences about the contributions of later stages to neural activity or psychophysical performance. A Web-based app is described that is based on the Malsburg Gabor-jet model (Lades et al., 1993), which allows easy specification of the V1 similarity of pairs of stimuli, no matter how intricate. The model predicts the psycho physical discriminability of metrically varying faces and complex blobs almost perfectly (Yue, Biederman, Mangini, von der Malsburg, & Amir, 2012), and serves as the input stage of a large family of contemporary neurocomputational models of vision.
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Margalit E, Biederman I, Tjan BS, Shah MP. What Is Actually Affected by the Scrambling of Objects When Localizing the Lateral Occipital Complex? J Cogn Neurosci 2017; 29:1595-1604. [DOI: 10.1162/jocn_a_01144] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
Abstract
The lateral occipital complex (LOC), the cortical region critical for shape perception, is localized with fMRI by its greater BOLD activity when viewing intact objects compared with their scrambled versions (resembling texture). Despite hundreds of studies investigating LOC, what the LOC localizer accomplishes—beyond distinguishing shape from texture—has never been resolved. By independently scattering the intact parts of objects, the axis structure defining the relations between parts was no longer defined. This led to a diminished BOLD response, despite the increase in the number of independent entities (the parts) produced by the scattering, thus indicating that LOC specifies interpart relations, in addition to specifying the shape of the parts themselves. LOC's sensitivity to relations is not confined to those between parts but is also readily apparent between objects, rendering it—and not subsequent “place” areas—as the critical region for the representation of scenes. Moreover, that these effects are witnessed with novel as well as familiar intact objects and scenes suggests that the relations are computed on the fly, rather than being retrieved from memory.
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25
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Neyens V, Bruffaerts R, Liuzzi AG, Kalfas I, Peeters R, Keuleers E, Vogels R, De Deyne S, Storms G, Dupont P, Vandenberghe R. Representation of Semantic Similarity in the Left Intraparietal Sulcus: Functional Magnetic Resonance Imaging Evidence. Front Hum Neurosci 2017; 11:402. [PMID: 28824405 PMCID: PMC5543089 DOI: 10.3389/fnhum.2017.00402] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2017] [Accepted: 07/20/2017] [Indexed: 11/13/2022] Open
Abstract
According to a recent study, semantic similarity between concrete entities correlates with the similarity of activity patterns in left middle IPS during category naming. We examined the replicability of this effect under passive viewing conditions, the potential role of visuoperceptual similarity, where the effect is situated compared to regions that have been previously implicated in visuospatial attention, and how it compares to effects of object identity and location. Forty-six subjects participated. Subjects passively viewed pictures from two categories, musical instruments and vehicles. Semantic similarity between entities was estimated based on a concept-feature matrix obtained in more than 1,000 subjects. Visuoperceptual similarity was modeled based on the HMAX model, the AlexNet deep convolutional learning model, and thirdly, based on subjective visuoperceptual similarity ratings. Among the IPS regions examined, only left middle IPS showed a semantic similarity effect. The effect was significant in hIP1, hIP2, and hIP3. Visuoperceptual similarity did not correlate with similarity of activity patterns in left middle IPS. The semantic similarity effect in left middle IPS was significantly stronger than in the right middle IPS and also stronger than in the left or right posterior IPS. The semantic similarity effect was similar to that seen in the angular gyrus. Object identity effects were much more widespread across nearly all parietal areas examined. Location effects were relatively specific for posterior IPS and area 7 bilaterally. To conclude, the current findings replicate the semantic similarity effect in left middle IPS under passive viewing conditions, and demonstrate its anatomical specificity within a cytoarchitectonic reference frame. We propose that the semantic similarity effect in left middle IPS reflects the transient uploading of semantic representations in working memory.
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Affiliation(s)
- Veerle Neyens
- Laboratory for Cognitive Neurology, Department of Neurosciences, University of LeuvenLeuven, Belgium
| | - Rose Bruffaerts
- Laboratory for Cognitive Neurology, Department of Neurosciences, University of LeuvenLeuven, Belgium.,Neurology Department, University Hospitals LeuvenLeuven, Belgium.,Department of Psychology, Centre for Speech, Language, and the Brain, University of CambridgeCambridge, United Kingdom
| | - Antonietta G Liuzzi
- Laboratory for Cognitive Neurology, Department of Neurosciences, University of LeuvenLeuven, Belgium
| | - Ioannis Kalfas
- Laboratory of Neurophysiology, Department of Neurosciences, University of LeuvenLeuven, Belgium
| | - Ronald Peeters
- Radiology Department, University Hospitals LeuvenLeuven, Belgium
| | - Emmanuel Keuleers
- Department of Communication and Information Sciences, Tilburg UniversityNetherlands
| | - Rufin Vogels
- Laboratory of Neurophysiology, Department of Neurosciences, University of LeuvenLeuven, Belgium
| | - Simon De Deyne
- Humanities and Social Sciences Group, Laboratory of Experimental Psychology, University of LeuvenLeuven, Belgium.,Computational Cognitive Science Laboratory, University of AdelaideAdelaide, SA, Australia
| | - Gert Storms
- Humanities and Social Sciences Group, Laboratory of Experimental Psychology, University of LeuvenLeuven, Belgium
| | - Patrick Dupont
- Laboratory for Cognitive Neurology, Department of Neurosciences, University of LeuvenLeuven, Belgium
| | - Rik Vandenberghe
- Laboratory for Cognitive Neurology, Department of Neurosciences, University of LeuvenLeuven, Belgium.,Neurology Department, University Hospitals LeuvenLeuven, Belgium
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26
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Margalit E, Shah MP, Tjan BS, Biederman I, Keller B, Brenner R. The Lateral Occipital Complex shows no net response to object familiarity. J Vis 2017; 16:3. [PMID: 27599373 PMCID: PMC5024672 DOI: 10.1167/16.11.3] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
In 1995, Malach et al. discovered an area whose fMRI BOLD response was greater when viewing intact, familiar objects than when viewing their scrambled versions (resembling texture). Since then hundreds of studies have explored this late visual region termed the Lateral Occipital Complex (LOC), which is now known to be critical for shape perception (James, Culham, Humphrey, Milner, & Goodale, 2003). Malach et al. (1995) discounted a role of familiarity by showing that “abstract” Henry Moore sculptures, unfamiliar to the subjects, also activated this region. This characterization of LOC as a region that responds to shape independently of familiarity has been accepted but never tested with control of the same low-level features. We assessed LOC's response to objects that had identical parts in two different arrangements, one familiar and the other novel. Malach was correct: There is no net effect of familiarity in LOC. However, a multivoxel correlation analysis showed that LOC does distinguish familiar from novel objects.
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27
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Denisova K, Feldman J, Su X, Singh M. Investigating shape representation using sensitivity to part- and axis-based transformations. Vision Res 2016; 126:347-361. [PMID: 26325393 DOI: 10.1016/j.visres.2015.07.004] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2015] [Revised: 07/06/2015] [Accepted: 07/10/2015] [Indexed: 10/22/2022]
Abstract
Part- and axis-based approaches organize shape representations in terms of simple parts and their spatial relationships. Shape transformations that alter qualitative part structure have been shown to be more detectable than those that preserve it. We compared sensitivity to various transformations that change quantitative properties of parts and their spatial relationships, while preserving qualitative part structure. Shape transformations involving changes in length, width, curvature, orientation and location were applied to a small part attached to a larger base of a two-part shape. Increment thresholds were estimated for each transformation using a 2IFC procedure. Thresholds were converted into common units of shape difference to enable comparisons across transformations. Higher sensitivity was consistently found for transformations involving a parameter of a single part (length, width, curvature) than those involving spatial relations between two parts (relative orientation and location), suggesting a single-part superiority effect. Moreover, sensitivity to shifts in part location - a biomechanically implausible shape transformation - was consistently poorest. The influence of region-based geometry was investigated via stereoscopic manipulation of figure and ground. Sensitivity was compared across positive parts (protrusions) and negative parts (indentations) for transformations involving a change in orientation or location. For changes in part orientation (biomechanically plausible), sensitivity was better for positive than negative parts; whereas for changes in part location (biomechanically implausible), no systematic difference was observed.
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Affiliation(s)
- Kristina Denisova
- Department of Psychology and Rutgers Center for Cognitive Science, Rutgers University, New Brunswick, NJ, United States.
| | - Jacob Feldman
- Department of Psychology and Rutgers Center for Cognitive Science, Rutgers University, New Brunswick, NJ, United States.
| | - Xiaotao Su
- Department of Psychology and Rutgers Center for Cognitive Science, Rutgers University, New Brunswick, NJ, United States.
| | - Manish Singh
- Department of Psychology and Rutgers Center for Cognitive Science, Rutgers University, New Brunswick, NJ, United States.
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28
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Wilder J, Feldman J, Singh M. The role of shape complexity in the detection of closed contours. Vision Res 2015; 126:220-231. [PMID: 26505685 DOI: 10.1016/j.visres.2015.10.011] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2015] [Revised: 10/15/2015] [Accepted: 10/17/2015] [Indexed: 11/19/2022]
Abstract
The detection of contours in noise has been extensively studied, but the detection of closed contours, such as the boundaries of whole objects, has received relatively little attention. Closed contours pose substantial challenges not present in the simple (open) case, because they form the outlines of whole shapes and thus take on a range of potentially important configural properties. In this paper we consider the detection of closed contours in noise as a probabilistic decision problem. Previous work on open contours suggests that contour complexity, quantified as the negative log probability (Description Length, DL) of the contour under a suitably chosen statistical model, impairs contour detectability; more complex (statistically surprising) contours are harder to detect. In this study we extended this result to closed contours, developing a suitable probabilistic model of whole shapes that gives rise to several distinct though interrelated measures of shape complexity. We asked subjects to detect either natural shapes (Exp. 1) or experimentally manipulated shapes (Exp. 2) embedded in noise fields. We found systematic effects of global shape complexity on detection performance, demonstrating how aspects of global shape and form influence the basic process of object detection.
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Affiliation(s)
- John Wilder
- Department of Computer Science, University of Toronto, Toronto, Canada.
| | - Jacob Feldman
- Department of Psychology, Center for Cognitive Science, Rutgers University - New Brunswick, USA
| | - Manish Singh
- Department of Psychology, Center for Cognitive Science, Rutgers University - New Brunswick, USA
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29
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Neural correlates of multiple object tracking strategies. Neuroimage 2015; 118:63-73. [DOI: 10.1016/j.neuroimage.2015.06.005] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2014] [Revised: 04/13/2015] [Accepted: 06/02/2015] [Indexed: 11/19/2022] Open
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30
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Eguchi A, Mender BMW, Evans BD, Humphreys GW, Stringer SM. Computational modeling of the neural representation of object shape in the primate ventral visual system. Front Comput Neurosci 2015; 9:100. [PMID: 26300766 PMCID: PMC4523947 DOI: 10.3389/fncom.2015.00100] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2015] [Accepted: 07/17/2015] [Indexed: 11/13/2022] Open
Abstract
Neurons in successive stages of the primate ventral visual pathway encode the spatial structure of visual objects. In this paper, we investigate through computer simulation how these cell firing properties may develop through unsupervised visually-guided learning. Individual neurons in the model are shown to exploit statistical regularity and temporal continuity of the visual inputs during training to learn firing properties that are similar to neurons in V4 and TEO. Neurons in V4 encode the conformation of boundary contour elements at a particular position within an object regardless of the location of the object on the retina, while neurons in TEO integrate information from multiple boundary contour elements. This representation goes beyond mere object recognition, in which neurons simply respond to the presence of a whole object, but provides an essential foundation from which the brain is subsequently able to recognize the whole object.
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Affiliation(s)
- Akihiro Eguchi
- Department of Experimental Psychology, Oxford Centre for Theoretical Neuroscience and Artificial Intelligence, Oxford UniversityOxford, UK
| | - Bedeho M. W. Mender
- Department of Experimental Psychology, Oxford Centre for Theoretical Neuroscience and Artificial Intelligence, Oxford UniversityOxford, UK
| | - Benjamin D. Evans
- Department of Experimental Psychology, Oxford Centre for Theoretical Neuroscience and Artificial Intelligence, Oxford UniversityOxford, UK
| | - Glyn W. Humphreys
- Department of Experimental Psychology, Oxford Cognitive Neuropsychology Centre, Oxford UniversityOxford, UK
| | - Simon M. Stringer
- Department of Experimental Psychology, Oxford Centre for Theoretical Neuroscience and Artificial Intelligence, Oxford UniversityOxford, UK
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31
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Qiu W, Hatori Y, Sakai K. Neural construction of 3D medial axis from the binocular fusion of 2D MAs. Neurocomputing 2015. [DOI: 10.1016/j.neucom.2014.08.019] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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32
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Layton OW, Mingolla E, Yazdanbakhsh A. Neural dynamics of feedforward and feedback processing in figure-ground segregation. Front Psychol 2014; 5:972. [PMID: 25346703 PMCID: PMC4193330 DOI: 10.3389/fpsyg.2014.00972] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2014] [Accepted: 08/15/2014] [Indexed: 11/13/2022] Open
Abstract
Determining whether a region belongs to the interior or exterior of a shape (figure-ground segregation) is a core competency of the primate brain, yet the underlying mechanisms are not well understood. Many models assume that figure-ground segregation occurs by assembling progressively more complex representations through feedforward connections, with feedback playing only a modulatory role. We present a dynamical model of figure-ground segregation in the primate ventral stream wherein feedback plays a crucial role in disambiguating a figure's interior and exterior. We introduce a processing strategy whereby jitter in RF center locations and variation in RF sizes is exploited to enhance and suppress neural activity inside and outside of figures, respectively. Feedforward projections emanate from units that model cells in V4 known to respond to the curvature of boundary contours (curved contour cells), and feedback projections from units predicted to exist in IT that strategically group neurons with different RF sizes and RF center locations (teardrop cells). Neurons (convex cells) that preferentially respond when centered on a figure dynamically balance feedforward (bottom-up) information and feedback from higher visual areas. The activation is enhanced when an interior portion of a figure is in the RF via feedback from units that detect closure in the boundary contours of a figure. Our model produces maximal activity along the medial axis of well-known figures with and without concavities, and inside algorithmically generated shapes. Our results suggest that the dynamic balancing of feedforward signals with the specific feedback mechanisms proposed by the model is crucial for figure-ground segregation.
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Affiliation(s)
- Oliver W Layton
- The Perception and Action Lab, Department of Cognitive Science, Rensselaer Polytechnic Institute Troy, NY, USA ; Vision Lab, Center for Computational Neuroscience and Neural Technology, Boston University Boston, MA, USA
| | - Ennio Mingolla
- Computational Vision Laboratory, Department of Speech-Language Pathology and Audiology, Northeastern University Boston, MA, USA
| | - Arash Yazdanbakhsh
- Vision Lab, Center for Computational Neuroscience and Neural Technology, Boston University Boston, MA, USA
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33
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Hatori Y, Sakai K. Early representation of shape by onset synchronization of border-ownership-selective cells in the V1-V2 network. JOURNAL OF THE OPTICAL SOCIETY OF AMERICA. A, OPTICS, IMAGE SCIENCE, AND VISION 2014; 31:716-729. [PMID: 24695133 DOI: 10.1364/josaa.31.000716] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Construction of surface is a crucial step toward the representation of shape through the integration of local information. Physiological studies have reported that the primary visual cortex (V1) codes the medial axis (MA) that is a skeletal structure equidistant from nearby contours, suggesting the early representation of surface in V1. Although the neural basis of surface construction has not been clarified, the onset synchronization of border ownership (BO)-selective cells is a plausible candidate for the generation of surface. We investigated computationally the representation of surface in a biophysically detailed model of primate V1-V2 networks. The simulation results showed that the simultaneous arrival of signals from BO-selective cells evoked strong responses of V1 cells located around the MA. The simulation results lead to a prediction that the perception of the direction of figure (DOF) depends on the degree of synchronous presentation of contour. We conducted a psychophysical experiment and showed that the perception of the DOF is biased toward a highly synchronized contour. These results suggest a crucial role of the onset synchronization of BO-selective cells for the construction of early representation of shape.
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Mannion DJ, Kersten DJ, Olman CA. Consequences of polar form coherence for fMRI responses in human visual cortex. Neuroimage 2013; 78:152-8. [PMID: 23608060 PMCID: PMC4044189 DOI: 10.1016/j.neuroimage.2013.04.036] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2013] [Accepted: 04/14/2013] [Indexed: 11/26/2022] Open
Abstract
Relevant features in the visual image are often spatially extensive and have complex orientation structure. Our perceptual sensitivity to such spatial form is demonstrated by polar Glass patterns, in which an array of randomly-positioned dot pairs that are each aligned with a particular polar displacement (rotation, for example) yield a salient impression of spatial structure. Such patterns are typically considered to be processed in two main stages: local spatial filtering in low-level visual cortex followed by spatial pooling and complex form selectivity in mid-level visual cortex. However, it remains unclear both whether reciprocal interactions within the cortical hierarchy are involved in polar Glass pattern processing and which mid-level areas identify and communicate polar Glass pattern structure. Here, we used functional magnetic resonance imaging (fMRI) at 7T to infer the magnitude of neural response within human low-level and mid-level visual cortex to polar Glass patterns of varying coherence (proportion of signal elements). The activity within low-level visual areas V1 and V2 was not significantly modulated by polar Glass pattern coherence, while the low-level area V3, dorsal and ventral mid-level areas, and the human MT complex each showed a positive linear coherence response functions. The cortical processing of polar Glass patterns thus appears to involve primarily feedforward communication of local signals from V1 and V2, with initial polar form selectivity reached in V3 and distributed to multiple pathways in mid-level visual cortex.
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Affiliation(s)
- Damien J Mannion
- Department of Psychology, University of Minnesota, Minneapolis, MN, USA.
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Greater sensitivity to nonaccidental than metric changes in the relations between simple shapes in the lateral occipital cortex. Neuroimage 2012; 63:1818-26. [DOI: 10.1016/j.neuroimage.2012.08.066] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2012] [Revised: 07/12/2012] [Accepted: 08/27/2012] [Indexed: 11/23/2022] Open
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Abstract
David Marr's approach to the study of vision has been tremendously influential. However, the approach proposes the goal of computing invariant shape descriptions from image-based information, a task that appears implausible, given the tremendous variation that can occur between images displaying a single object. Theorists in the field of three-dimensional object recognition have rejected the approach of computing object-centered representations, and instead propose representations of objects from the perspective of a viewer. If object-centered descriptions of objects exist in the brain, they are more likely to underlie motor interaction with objects rather than visual object understanding.
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Affiliation(s)
- William G Hayward
- Department of Psychology, University of Hong Kong, Pokfulam Road, Hong Kong, China
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