Symmetry and repetition in perspective

Vloed, Gert van der; Csathó, Árpád; Helm, Peter A. van der

doi:10.1016/j.actpsy.2005.03.006

Cited by 28 publications

(39 citation statements)

References 16 publications

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“…To start, note that it is true that symmetric objects yield a symmetric projection on the retina only if viewed head-on. However, the degradation of 2D symmetry induced by perspective is gradual and systematic [27][28][29][30]. For instance, as Figure 2d,e illustrates, the lines connecting symmetric elements are not parallel any more under perspective distortion, but adjacent lines are still approximately parallel.…”

Section: The Role Of Symmetry Processing In Perceptual Organizationmentioning

confidence: 97%

Behind the Looking-Glass: A Review on Human Symmetry Perception

2010

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The human visual system is highly proficient in extracting bilateral symmetry from visual input. This paper reviews empirical and theoretical work on human symmetry perception with a focus on recent issues such as its neural underpinnings. Symmetry detection is shown to be a versatile, ongoing visual process that interacts with other visual processes. Evidence seems to converge towards the idea that symmetry detection is subserved by a preprocessing stage involving spatial filters followed by information integration across the visual field in higher-tier cortical areas.

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Section: The Role Of Symmetry Processing In Perceptual Organizationmentioning

confidence: 97%

Behind the Looking-Glass: A Review on Human Symmetry Perception

2010

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“…Specifically, this process would require that the visual system first obtain an estimate of slant from available depth cues to mentally rotate (normalize) the image to the frontoparallel plane where regularity detection could proceed unhindered (on this mentally rotated image, rather than the retinal image). Others however, have suggested that during perspective distortions, the remaining regularities in the retinal image are sufficient for symmetry detection to take place, without requiring normalization, a process typically referred to as the retinal structure account of symmetry processing (Jenkins, 1983; van der Vloed et al, 2005; Wagemans et al, 1993). Attempts to discern between these two putative mechanisms have returned equivocal conclusions in the psychophysical literature however, and we refer the interested reader to the study by van der Vloed et al (2005) for an excellent discussion on the topic.…”

Section: Introductionmentioning

confidence: 99%

Emergence of symmetry selectivity in the visual areas of the human brain: fMRI responses to symmetry presented in both frontoparallel and slanted planes

Keefe

Gouws

Sheldon

et al. 2018

Human Brain Mapping

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Symmetry is effortlessly perceived by humans across changes in viewing geometry. Here, we re‐examined the network subserving symmetry processing in the context of up‐to‐date retinotopic definitions of visual areas. Responses in object selective cortex, as defined by functional localizers, were also examined. We further examined responses to both frontoparallel and slanted symmetry while manipulating attention both toward and away from symmetry. Symmetry‐specific responses first emerge in V3 and continue across all downstream areas examined. Of the retinotopic areas, ventral occipital VO1 showed the strongest symmetry response, which was similar in magnitude to the responses observed in object selective cortex. Neural responses were found to increase with both the coherence and folds of symmetry. Compared to passive viewing, drawing attention to symmetry generally increased neural responses and the correspondence of these neural responses with psychophysical performance. Examining symmetry on the slanted plane found responses to again emerge in V3, continue through downstream visual cortex, and be strongest in VO1 and LOB. Both slanted and frontoparallel symmetry evoked similar activity when participants performed a symmetry‐related task. However, when a symmetry‐unrelated task was performed, fMRI responses to slanted symmetry were reduced relative to their frontoparallel counterparts. These task‐related changes provide a neural signature that suggests slant has to be computed ahead of symmetry being appropriately extracted, known as the “normalization” account of symmetry processing. Specifically, our results suggest that normalization occurs naturally when attention is directed toward symmetry and orientation, but becomes interrupted when attention is directed away from these features.

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“…This could be because symmetry analysis follows an effortful and potentially time-consuming normalization process [78], or because symmetry analysis is based on the degraded structure in the retinal image after slanting. Van der Vloed, Csathó and van der Helm [79] argued in favour of the retinal structure hypothesis, and against the normalization hypothesis.…”

Section: Question Four: Is the Neural Response To Symmetry View Invarmentioning

confidence: 99%

Brain Activity in Response to Visual Symmetry

2014

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Abstract:A number of studies have explored visual symmetry processing by measuring event related potentials and neural oscillatory activity. There is a sustained posterior negativity (SPN) related to the presence of symmetry. There is also functional magnetic resonance imaging (MRI) activity in extrastriate visual areas and in the lateral occipital complex. We summarise the evidence by answering six questions. (1) Is there an automatic and sustained response to symmetry in visual areas? Answer: Yes, and this suggests automatic processing of symmetry. (2) Which brain areas are involved in symmetry perception? Answer: There is an extended network from extrastriate areas to higher areas. (3) Is reflection special? Answer: Reflection is the optimal stimulus for a more general regularity-sensitive network. (4) Is the response to symmetry independent of view angle? Answer: When people classify patterns as symmetrical or random, the response to symmetry is view-invariant. When people attend to other dimensions, the network responds to residual regularity in the image. (5) How are brain rhythms in the two hemispheres altered during symmetry perception? Answer: Symmetry processing (rather than presence) produces more alpha desynchronization in the right posterior regions. Finally, (6) does symmetry processing produce positive affect? Answer: Not in the strongest sense, but behavioural measures reveal implicit positive evaluation of abstract symmetry.

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Symmetry and repetition in perspective

Cited by 28 publications

References 16 publications

Behind the Looking-Glass: A Review on Human Symmetry Perception

Behind the Looking-Glass: A Review on Human Symmetry Perception

Emergence of symmetry selectivity in the visual areas of the human brain: fMRI responses to symmetry presented in both frontoparallel and slanted planes

Brain Activity in Response to Visual Symmetry

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