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Specificity of switching attention in mechanisms of visual thinking in hemispheres of the human brain

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Specificity of switching attention in mechanisms of visual thinking in hemispheres of the human brain

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Abstract

Results of experiments on the sequence of stages of visual perception and theoretical notions on the structure of invariant descriptions of classes of visual objects are considered. Two interrelated theses on the mechanisms of visual thinking in the hemispheres of the human brain are substantiated: (1) in visual thinking each hemisphere of the human brain uses (the “a part through parts”) structural principle of describing objects and scenes; and (2) differences in visual recognition and classification between the dominant (with respect to speech) and subdominant hemispheres are related to the mechanisms of the switching attention system.

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RP is a case of "developmental" prosopagnosia who, according to brain-imaging segmentation data, shows reduction in volume of a limited set of structures of the right hemisphere. RP is as accurate as control subjects in tasks requiring the perception of nonface objects (e.g., matching subordinate labels to exemplars, naming two-tone images), with the exception of one perceptual task: The matching of different perspectives of amoebae-like stimuli (i.e., volumes made of a single smooth surface). In terms of speed ("efficiency") of responses, RP's performance falls clearly outside the normal limits also in other tasks that include "natural" but nonface stimuli (i.e., animals, artia facts). Specifically, RP is slow in perceptual judgments made at very low (subordinate) levels of semantic categorization and for objects and artifacts whose geometry present much curved features and surface information. We conclude from these analyses that prosopagnosia can be the result of a deficit in the representation of basic geometric volumes made of curved surface. In turn, this points to the importance (necessity) for the normal visual system of such curved and volumetric information in the identification of human faces.
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People are remarkably adroit at understanding other social agents. Quite how these information-processing abilities are realized, however, remains open to debate and empirical scrutiny. In particular, little is known about basic aspects of person perception, such as the operations that support people's ability to categorize (i.e., assign persons to groups) and individuate (i.e., discriminate among group members) others. In an attempt to rectify this situation, the current research focused on the initial perceptual stages of person construal and considered: (i) hemispheric differences in the efficiency of categorization and individuation; and (ii) the neural activity that supports these social-cognitive operations. Noting the greater role played by configural processing in individuation than categorization, it was expected that performance on the former task would be enhanced when stimuli (i.e., faces) were presented to the right rather than to the left cerebral hemisphere. The results of two experiments (Experiment 1—healthy individuals; Experiment 2—split-brain patient) confirmed this prediction. Extending these findings, a final neuroimaging investigation revealed that individuation is accompanied by neural activity in regions of the temporal and prefrontal cortices, especially in the right hemisphere. We consider the implications of these findings for contemporary treatments of person perception.
On Signs Used by Brain Hemispheres in Recognition of Geometric Fig-ures
  • Meerson
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