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Contour integration and aging: the effects of element spacing, orientation alignment and stimulus duration.
MedLine Citation:
PMID:  23801978     Owner:  NLM     Status:  PubMed-not-MEDLINE    
The ability to extract contours in cluttered visual scenes, which is a crucial step in visual processing, declines with healthy aging, but the reasons for this decline are not well understood. In three experiments, we examined how the effect of aging on contour discrimination varies as a function of contour and distracter inter-element spacing, collinearity, and stimulus duration. Spiral-shaped contours composed of Gabors were embedded within a field of distracter Gabors of uniform density. In a four alternative forced-choice task, younger and older subjects were required to report the global orientation of the contour. In Experiment 1, the absolute contour element spacing varied from two to eight times the Gabor wavelength and contour element collinearity was disrupted with five levels of orientation jitter. Contour discrimination accuracy was lower in older subjects, but the effect of aging did not vary with contour spacing or orientation jitter. Experiment 2 found that decreasing stimulus durations from 0.8 to 0.04 s had a greater effect on older subjects' performance, but only for less salient contours. Experiment 3 examined the effect of the background on contour discrimination by varying the spacing and orientation of the distracter elements for contours with small and large absolute spacing. As in Experiment, the effect of aging did not vary with absolute contour spacing. Decreasing the distracter spacing, however, had a greater detrimental effect on accuracy in older subjects compared to younger subjects. Finally, both groups showed equally high accuracy when all distracters were iso-oriented. In sum, these findings suggest that aging does not affect the sensitivity of contour integration to proximity or collinearity. However, contour integration in older adults is slower and is especially vulnerable when distracters are denser than contour elements.
Eugenie Roudaia; Patrick J Bennett; Allison B Sekuler
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Publication Detail:
Type:  Journal Article     Date:  2013-06-20
Journal Detail:
Title:  Frontiers in psychology     Volume:  4     ISSN:  1664-1078     ISO Abbreviation:  Front Psychol     Publication Date:  2013  
Date Detail:
Created Date:  2013-06-26     Completed Date:  2013-06-27     Revised Date:  2013-08-13    
Medline Journal Info:
Nlm Unique ID:  101550902     Medline TA:  Front Psychol     Country:  Switzerland    
Other Details:
Languages:  eng     Pagination:  356     Citation Subset:  -    
Vision and Cognitive Neuroscience Lab, Department of Psychology, Neuroscience and Behaviour, McMaster University Hamilton, ON, Canada ; Institute of Neuroscience, Multisensory Cognition Research Group, Trinity College Dublin Dublin, Ireland.
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