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Perceptual Categories (perceptual + category)

Distribution by Scientific Domains
Psychology66%

Selected Abstracts

Evidence of rapid correlation-based perceptual category learning by 4-month-olds

INFANT AND CHILD DEVELOPMENT, Issue 5 2005
Denis Mareschal
Abstract Young infants are very sensitive to feature distribution information in the environment. However, existing work suggests that they do not make use of correlation information to form certain perceptual categories until at least 7 months of age. We suggest that the failure to use correlation information is a by-product of familiarization procedures that encourage infants to over encode individual exemplars rather than relations across exemplars. By changing the exemplar presentation regime to one in which exemplars are rapidly (2 s durations) and repeatedly presented we find that 4-month-olds can form perceptual categories on the basis of feature correlation information. In addition, this ability emerges rapidly between 114 and 134 days. We argue that the ability to process correlation information is present very early on but that the demonstration of that ability in categorization tasks is mediated by the demands of the task the infant is tested with. Copyright © 2005 John Wiley & Sons, Ltd. [source]

Modulatory Effects of Transcranial Direct Current Stimulation on Laser-Evoked Potentials

PAIN MEDICINE, Issue 1 2009
Gabor Csifcsak MD
ABSTRACT Objective., Invasive stimulation of the motor cortex has been used for years to alleviate chronic intractable pain in humans. In our study, we have investigated the effect of transcranial direct current stimulation (tDCS), a noninvasive stimulation method, for manipulating the excitability of cortical motor areas on laser evoked potentials (LEP) and acute pain perception. Designs and Settings., The amplitude of the N1, N2, and P2 LEP components of 10 healthy volunteers were evaluated prior to and following anodal, cathodal, and sham stimulation of the primary motor cortex. In a separate experiment subjective, pain rating scores of 16 healthy subjects in two perceptual categories (warm sensation, mild pain) were also analyzed. Results., Cathodal tDCS significantly reduced the amplitude of N2 and P2 components compared with anodal or sham stimulation. However, neither of the tDCS types modified significantly the laser energy values necessary to induce moderate pain. In a separate experiment, cathodal stimulation significantly diminished mild pain sensation only when laser-stimulating the hand contralateral to the side of tDCS, while anodal stimulation modified warm sensation. Conclusions., The possible underlying mechanisms of our findings in view of recent neuroimaging studies are discussed. To our knowledge this study is the first to demonstrate the mild antinociceptive effect of tDCS over the primary motor cortex in healthy volunteers. [source]

What Do People Live On?

ANTHROPOLOGY OF WORK REVIEW, Issue 1 2010
Living Wages in India
Abstract The question of what people are expected to live on raises many issues, foregrounding the rather metaphysical question of how people are viewed as people. To argue for the implementation of a really viable living wage one would have to argue against the dehumanization of bodies, of construction of personhoods that demean humans, and to visualize a change in worldview and perceptual categories. Living wage discussions on India must go beyond economies to address the cultural/cosmological factors that mark power relations and shape social categories, and this must be done against the backdrop of overpopulation and abject poverty. [source]

Evidence of rapid correlation-based perceptual category learning by 4-month-olds

INFANT AND CHILD DEVELOPMENT, Issue 5 2005
Denis Mareschal
Abstract Young infants are very sensitive to feature distribution information in the environment. However, existing work suggests that they do not make use of correlation information to form certain perceptual categories until at least 7 months of age. We suggest that the failure to use correlation information is a by-product of familiarization procedures that encourage infants to over encode individual exemplars rather than relations across exemplars. By changing the exemplar presentation regime to one in which exemplars are rapidly (2 s durations) and repeatedly presented we find that 4-month-olds can form perceptual categories on the basis of feature correlation information. In addition, this ability emerges rapidly between 114 and 134 days. We argue that the ability to process correlation information is present very early on but that the demonstration of that ability in categorization tasks is mediated by the demands of the task the infant is tested with. Copyright © 2005 John Wiley & Sons, Ltd. [source]

Looking for faces: Attention modulates early occipitotemporal object processing

PSYCHOPHYSIOLOGY, Issue 3 2004
Andreas Lueschow
Abstract Looking for somebody's face in a crowd is one of the most important examples of visual search. For this goal, attention has to be directed to a well-defined perceptual category. When this categorically selective process starts is, however, still unknown. To this end, we used magnetoencephalography (MEG) recorded over right human occipitotemporal cortex to investigate the time course of attentional modulation of perceptual processes elicited by faces and by houses. The first face-distinctive MEG response was observed at 160,170 ms (M170). Nevertheless, attention did not start to modulate face processing before 190 ms. The first house-distinctive MEG activity was also found around 160,170 ms. However, house processing was not modulated by attention before 280 ms (90 ms later than face processing). Further analysis revealed that the attentional modulation of face processing is not due to later, for example, back-propagated activation of the M170 generator. Rather, subsequent stages of occipitotemporal object processing were modulated in a category-specific manner and with preferential access to face processing. [source]