Gestalt laws of perceptual organization in an embedded figures task: Evidence for hemispheric specialization

Kleeck, Michael H. Van; Kosslyn, Stephen M.

doi:10.1016/0028-3932(89)90100-0

Cited by 25 publications

(14 citation statements)

References 20 publications

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“…37,38 Others have suggested that the visuospatial capacity of the left hemisphere is categorical, whereas that of the right is metric. 39,40 Clinical findings in patients with lateralized brain lesions affecting visually related areas appear to support this dichotomy. 41 The asymmetry in the size of neurons in the visual cortex reported here may reflect an anatomical basis for hemispheric specializations others have reported for complex visual perceptual tasks.…”

Section: Discussionmentioning

confidence: 94%

Neuronal asymmetries in primary visual cortex of dyslexic and nondyslexic brains

1999

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Dyslexic brains exhibit histologic changes in the magnocellular (magno) cells of the lateral geniculate nucleus, and consistent with these changes, dyslexics demonstrate abnormal visually evoked potentials and brain activation to magno‐specific stimuli. The current study was aimed at determining whether these findings were associated with changes in the primary visual cortex with the prediction that magno components of this cortex would be affected. We measured cross‐sectional neuronal areas in primary visual cortex (area 17) in dyslexic and nondyslexic autopsy specimens. There was a significant interaction between hemispheres and diagnostic category; ie, nondyslexic brains had larger neurons in the left hemisphere, whereas dyslexic brains had no asymmetry. On the other hand, cell layers associated with magno input from the lateral geniculate nucleus did not show consistent changes in dyslexic brains. Thus, there is a neuronal size asymmetry in favor of the left primary visual cortex in nondyslexics that is absent in dyslexic brains. This is yet another example of anomalous expression of cerebral asymmetry in dyslexia similar to that of the planum temporale, which in our view reflects abnormality in circuits involved in reading. Ann Neurol 1999;46:189–196

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Section: Discussionmentioning

confidence: 94%

Neuronal asymmetries in primary visual cortex of dyslexic and nondyslexic brains

1999

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“…One possible explanation would be the holistic processing of stimuli which is generally more related to the right hemisphere than to the left one [59]–[60]. Right hemisphere, for example, processes more global aspects of a visual stimulus, while left hemisphere is better in processing local aspects [61]–[63].…”

Section: Discussionmentioning

confidence: 99%

It Takes Two–Skilled Recognition of Objects Engages Lateral Areas in Both Hemispheres

et al. 2011

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Our object recognition abilities, a direct product of our experience with objects, are fine-tuned to perfection. Left temporal and lateral areas along the dorsal, action related stream, as well as left infero-temporal areas along the ventral, object related stream are engaged in object recognition. Here we show that expertise modulates the activity of dorsal areas in the recognition of man-made objects with clearly specified functions. Expert chess players were faster than chess novices in identifying chess objects and their functional relations. Experts' advantage was domain-specific as there were no differences between groups in a control task featuring geometrical shapes. The pattern of eye movements supported the notion that experts' extensive knowledge about domain objects and their functions enabled superior recognition even when experts were not directly fixating the objects of interest. Functional magnetic resonance imaging (fMRI) related exclusively the areas along the dorsal stream to chess specific object recognition. Besides the commonly involved left temporal and parietal lateral brain areas, we found that only in experts homologous areas on the right hemisphere were also engaged in chess specific object recognition. Based on these results, we discuss whether skilled object recognition does not only involve a more efficient version of the processes found in non-skilled recognition, but also qualitatively different cognitive processes which engage additional brain areas.

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“…Grouping between individual items allows to identify global forms that emerge from the way local elements are organized (Kimchi, 2000; Kimchi et al, 2005). Information at the global and local levels are processed by specialized neural pathways, and structure the visual environment in a hierarchical manner (Delis et al, 1986; van Kleeck, 1989; Hübner and Volberg, 2005). A number of studies suggest that grouping mechanisms can occur automatically under conditions of inattention (Driver et al, 2001; Müller et al, 2010).…”

Section: Introductionmentioning

confidence: 99%

Patients with Schizophrenia Do Not Preserve Automatic Grouping When Mentally Re-Grouping Figures: Shedding Light on an Ignored Difficulty

Giersch¹,

Assche²,

Lefebvre³

et al. 2012

Front. Psychology

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Looking at a pair of objects is easy when automatic grouping mechanisms bind these objects together, but visual exploration can also be more flexible. It is possible to mentally “re-group” two objects that are not only separate but belong to different pairs of objects. “Re-grouping” is in conflict with automatic grouping, since it entails a separation of each item from the set it belongs to. This ability appears to be impaired in patients with schizophrenia. Here we check if this impairment is selective, which would suggest a dissociation between grouping and “re-grouping,” or if it impacts on usual, automatic grouping, which would call for a better understanding of the interactions between automatic grouping and “re-grouping.” Sixteen outpatients with schizophrenia and healthy controls had to identify two identical and contiguous target figures within a display of circles and squares alternating around a fixation point. Eye-tracking was used to check central fixation. The target pair could be located in the same or separate hemifields. Identical figures were grouped by a connector (grouped automatically) or not (to be re-grouped). Attention modulation of automatic grouping was tested by manipulating the proportion of connected and unconnected targets, thus prompting subjects to focalize on either connected or unconnected pairs. Both groups were sensitive to automatic grouping in most conditions, but patients were unusually slowed down for connected targets while focalizing on unconnected pairs. In addition, this unusual effect occurred only when targets were presented within the same hemifield. Patients and controls differed on this asymmetry between within- and across-hemifield presentation, suggesting that patients with schizophrenia do not re-group figures in the same way as controls do. We discuss possible implications on how “re-grouping” ties in with ongoing, automatic perception in healthy volunteers.

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Gestalt laws of perceptual organization in an embedded figures task: Evidence for hemispheric specialization

Cited by 25 publications

References 20 publications

Neuronal asymmetries in primary visual cortex of dyslexic and nondyslexic brains

Neuronal asymmetries in primary visual cortex of dyslexic and nondyslexic brains

It Takes Two–Skilled Recognition of Objects Engages Lateral Areas in Both Hemispheres

Patients with Schizophrenia Do Not Preserve Automatic Grouping When Mentally Re-Grouping Figures: Shedding Light on an Ignored Difficulty

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