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Titolo:
Hemispheric asymmetries in global/local processing are modulated by perceptual salience
Autore:
Fink, GR; Marshall, JC; Halligan, PW; Dolan, RJ;
Indirizzi:
Neurol Inst, Wellcome Dept Cognit Neurol, London, England Neurol Inst London England Wellcome Dept Cognit Neurol, London, England Univ Dusseldorf, Neurol Klin, D-4000 Dusseldorf, Germany Univ Dusseldorf Dusseldorf Germany D-4000 in, D-4000 Dusseldorf, Germany Radcliffe Infirm, Neuropsychol Unit, Oxford, England Radcliffe Infirm Oxford England irm, Neuropsychol Unit, Oxford, England Dept Expt Psychol, Oxford OX1 3UD, England Dept Expt Psychol Oxford England OX1 3UD sychol, Oxford OX1 3UD, England Royal Free Hosp, Sch Med, London, England Royal Free Hosp London England oyal Free Hosp, Sch Med, London, England
Titolo Testata:
NEUROPSYCHOLOGIA
fascicolo: 1, volume: 37, anno: 1999,
pagine: 31 - 40
SICI:
0028-3932(199901)37:1<31:HAIGPA>2.0.ZU;2-F
Fonte:
ISI
Lingua:
ENG
Soggetto:
POSITRON EMISSION TOMOGRAPHY; SPATIAL-FREQUENCY CHANNELS; HIERARCHICAL STIMULI; SELECTIVE ATTENTION; VISUAL-ATTENTION; PRECEDENCE; CORTEX; AREAS; SPECIALIZATION; LESIONS;
Keywords:
spatial frequency; early visual cortex; hemispheric interaction; directed visual attention; functional imaging;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Social & Behavioral Sciences
Life Sciences
Citazioni:
43
Recensione:
Indirizzi per estratti:
Indirizzo: Fink, GR Neurol Inst, Wellcome Dept Cognit Neurol, London, England Neurol Inst London England Dept Cognit Neurol, London, England
Citazione:
G.R. Fink et al., "Hemispheric asymmetries in global/local processing are modulated by perceptual salience", NEUROPSYCHO, 37(1), 1999, pp. 31-40

Abstract

It has been claimed that a left hemisphere bias toward local and right hemisphere bias toward global visual processing can be explained in terms of specialization for relatively high and low spatial frequencies, respectively. Using non-representational figures, we tested this hypothesis in experiment 1 using positron emission tomography (PET) measures of cerebral activityin 10 normal volunteers. In each block of trials subjects viewed either a relatively high or a relatively low spatial frequency grating. The orientation (vertical or horizontal) of the grating changed from trial to trial. Ina directed attention task, subjects reported the orientation of either thewhole stimulus (globally directed attention) or the orientation of the component parts thereof (locally directed attention). A significant interaction between hierarchical processing level (global or local) and stimulus level (relatively high or relatively low spatial frequency within the absolute low spatial frequency range) was found. Globally directed attention led to significantly increased cerebral activity in the right hemisphere when relatively high spatial frequency stimuli were used but not when relatively lowspatial frequency stimuli were used. Likewise, locally directed attention increased cerebral activity when low but not high spatial frequency stimuliwere used. On the basis of these results we suggest that perceptual salience of the global or local form modulates hemispheric processing asymmetriesin early visual cortex. In experiment 2, the perceptual salience of globalform in relatively high spatial frequency stimuli and of local form in relatively low spatial frequency stimuli was confirmed in a reaction time (RT)study. In combination, the results of the two experiments suggest that perceptual salience takes precedence over spatial frequency (within the range studied here) in determining the cerebral organization of global/local processing. (C) 1998 Elsevier Science Ltd. All rights reserved.

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Documento generato il 23/01/20 alle ore 18:15:22