Detection of symmetry and anti-symmetry
| Autor: | Sharon L. Sally, Rick Gurnsey, Sandra Mancini |
|---|---|
| Rok vydání: | 2003 |
| Předmět: |
Signal Detection
Psychological media_common.quotation_subject Visual Acuity Poison control Grey scale 050105 experimental psychology Eccentricity Symmetry 03 medical and health sciences 0302 clinical medicine Nuclear magnetic resonance Psychophysics Humans 0501 psychology and cognitive sciences Attention Selective attention Eccentricity (behavior) Second-order channels Spatial Vision media_common Physics Analysis of Variance Vision Binocular Polarity 05 social sciences Sensory Systems Symmetry (physics) Ophthalmology Pattern Recognition Visual Fixation (visual) Spatial frequency Social psychology 030217 neurology & neurosurgery Photic Stimulation |
| Zdroj: | Vision research. 45(16) |
| ISSN: | 0042-6989 |
| Popis: | To assess the role of second-order channels in symmetry perception we measured the effects of check size, spatial frequency content, eccentricity and grey scale range on the detection of symmetrical and anti-symmetrical patterns. Thresholds for symmetrical stimuli were only moderately affected by these manipulations. Anti-symmetrical stimuli composed of large black and white checks elicited low thresholds. However, anti-symmetry became essentially undetectable at small check sizes. Removing low frequencies from large-check-size, anti-symmetrical stimuli had little effect on thresholds whereas removing high frequencies had a pronounced effect. Moving the stimuli from fixation to 8� eccentricity caused a dramatic increase in thresholds for anti-symmetrical stimuli but not symmetrical stimuli. When the grey scale range was increased anti-symmetry was undetectable at any check size whereas symmetry was easily seen at all. We argue that these results and others in the literature suggest that anti-symmetry is only detected under conditions favourable to selective attention. � 2005 Elsevier Ltd. All rights reserved. |
| Databáze: | OpenAIRE |
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