The effect of normal aging on closed contour shape discrimination.

Our experiments explore whether contour processing of closed shapes is altered by healthy aging. Contour processing was measured using a closed contour (circle or ellipse) constructed of Gabor elements. The contour was presented either on a blank background or embedded in noise (identical Gabor elements of random orientation). Twenty-one older (age range: 61-80 years) and 21 younger (age range: 22-38 years) adults participated in three experiments: 1) the number of Gabors comprising the contour was fixed (10, 12 or 15) and the threshold aspect ratio required to discriminate the shape (circle versus ellipse) was measured; 2) orientation jitter was added to the Gabor elements comprising the contour and shape aspect ratio discrimination thresholds were measured; and 3) the aspect ratio was fixed (three times the individual threshold aspect ratios) and the threshold number of elements required to determine the shape was measured. Older adults required a larger number of elements to discriminate the global contour shape (F(1, 41) = 15, p < 0.001), even when stimulus saliency was matched for contrast sensitivity and aspect ratio threshold. This finding is consistent with other recent work showing deteriorations in cortically mediated visual processing with age.

[1]  G. B. Wetherill,et al.  SEQUENTIAL ESTIMATION OF POINTS ON A PSYCHOMETRIC FUNCTION. , 1965, The British journal of mathematical and statistical psychology.

[2]  G. Mitchison,et al.  Long axons within the striate cortex: their distribution, orientation, and patterns of connection. , 1982, Proceedings of the National Academy of Sciences of the United States of America.

[3]  R. Sekuler,et al.  Contrast sensitivity throughout adulthood , 1982, Vision Research.

[4]  R A Weale,et al.  Age and the transmittance of the human crystalline lens. , 1988, The Journal of physiology.

[5]  P. D. Spear,et al.  Neural bases of visual deficits during aging , 1993, Vision Research.

[6]  Gunilla Haegerstrom-Portnoy,et al.  Age changes in the optical density of human ocular media , 1993 .

[7]  David J. Field,et al.  Contour integration by the human visual system: Evidence for a local “association field” , 1993, Vision Research.

[8]  I Kovács,et al.  A closed curve is much more than an incomplete one: effect of closure in figure-ground segmentation. , 1993, Proceedings of the National Academy of Sciences of the United States of America.

[9]  D. Whitaker,et al.  Factors affecting light-adapted pupil size in normal human subjects. , 1994, Investigative ophthalmology & visual science.

[10]  David J. Field,et al.  Contour integration in strabismic amblyopia: The sufficiency of an explanation based on positional uncertainty , 1997, Vision Research.

[11]  U. Polat,et al.  Collinear stimuli regulate visual responses depending on cell's contrast threshold , 1998, Nature.

[12]  D. Field,et al.  Integration of contours: new insights , 1999, Trends in Cognitive Sciences.

[13]  J. G. Evans,et al.  Oxford textbook of geriatric medicine , 2000 .

[14]  Yizhong Wang,et al.  Effects of Aging on Shape Discrimination , 2001, Optometry and vision science : official publication of the American Academy of Optometry.

[15]  A. Peters,et al.  The effects of aging on layer 1 of primary visual cortex in the rhesus monkey. , 2001, Cerebral cortex.

[16]  A. Drewnowski,et al.  Journals of Gerontology , 2001 .

[17]  Jocelyn Faubert,et al.  Aging and bilateral symmetry detection. , 2002, The journals of gerontology. Series B, Psychological sciences and social sciences.

[18]  Wu Li,et al.  Global contour saliency and local colinear interactions. , 2001, Journal of neurophysiology.

[19]  A. Leventhal,et al.  GABA and Its Agonists Improved Visual Cortical Function in Senescent Monkeys , 2003, Science.

[20]  J. Nelson,et al.  Intracortical facilitation among co-oriented, co-axially aligned simple cells in cat striate cortex , 2004, Experimental Brain Research.

[21]  Christopher Patrick Taylor,et al.  Aging Reduces Center-Surround Antagonism in Visual Motion Processing , 2005, Neuron.

[22]  Yuanye Ma,et al.  Degradation of signal timing in cortical areas V1 and V2 of senescent monkeys. , 2005, Cerebral cortex.

[23]  S. Kuai,et al.  Constant contour integration in peripheral vision for stimuli with good Gestalt properties. , 2006, Journal of vision.

[24]  C. Gilbert,et al.  Contour Saliency in Primary Visual Cortex , 2006, Neuron.

[25]  Maria Michela Del Viva,et al.  Visual spatial integration in the elderly. , 2007, Investigative ophthalmology & visual science.

[26]  Dennis M. Levi,et al.  Global contour processing in amblyopia , 2007, Vision Research.

[27]  Manfred Fahle,et al.  Closure facilitates contour integration , 2007, Vision Research.

[28]  C. Gilbert,et al.  Learning to Link Visual Contours , 2008, Neuron.

[29]  John S Werner,et al.  The effect of senescence on orientation discrimination and mechanism tuning. , 2008, Journal of vision.

[30]  Gunter Loffler,et al.  Perception of contours and shapes: Low and intermediate stage mechanisms , 2008, Vision Research.

[31]  Allison B. Sekuler,et al.  The effect of aging on contour integration , 2008, Vision Research.

[32]  Allison M. McKendrick,et al.  Aging alters surround modulation of perceived contrast. , 2009, Journal of vision.

[33]  Allison B. Sekuler,et al.  The effect of aging on the orientational selectivity of the human visual system , 2009, Vision Research.