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The ups and downs of global motion perception: a paradoxical advantage for smaller stimuli in the aging visual system.

Hutchinson CV, Ledgeway T, Allen HA - Front Aging Neurosci (2014)

Bottom Line: We found that older adults' performance was relatively unaffected by changes in aperture size, the number and density of local elements in the display.These findings suggest that the normal (disease-free) aging process does not lead to a general decline in perceptual ability and in some cases may be visually advantageous.These include age-related changes in spatial summation, reduced cortical inhibition, neural blur and attentional resource allocation.

View Article: PubMed Central - PubMed

Affiliation: College of Medicine, Biological Sciences and Psychology, School of Psychology, University of Leicester Leicester, UK.

ABSTRACT
Recent evidence suggests that normal aging is typically accompanied by impairment in the ability to perceive the global (overall) motion of visual objects in the world. The purpose of this study was to examine the interplay between age-related changes in the ability to perceive translational global motion (up vs. down) and important factors such as the spatial extent (size) over which movement occurs and how cluttered the moving elements are (density). We used random dot kinematograms (RDKs) and measured motion coherence thresholds (% signal elements required to reliably discriminate global direction) for young and older adults. We did so as a function of the number and density of local signal elements, and the aperture area in which they were displayed. We found that older adults' performance was relatively unaffected by changes in aperture size, the number and density of local elements in the display. In young adults, performance was also insensitive to element number and density but was modulated markedly by display size, such that motion coherence thresholds decreased as aperture area increased (participants required fewer local elements to move coherently to determine the overall image direction). With the smallest apertures tested, young participants' motion coherence thresholds were considerably higher (~1.5 times worse) than those of their older counterparts. Therefore, when RDK size is relatively small, older participants were actually better than young participants at processing global motion. These findings suggest that the normal (disease-free) aging process does not lead to a general decline in perceptual ability and in some cases may be visually advantageous. The results have important implications for the understanding of the consequences of aging on visual function and a number of potential explanations are explored. These include age-related changes in spatial summation, reduced cortical inhibition, neural blur and attentional resource allocation.

No MeSH data available.


Related in: MedlinePlus

Experiment 3: Mean global motion coherence thresholds for “young” and “old” participants at two dot densities (0.44 and 1.13 dots/deg2) with an aperture size of 113 deg2. Error bars = ±1 S.E.M.
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Figure 4: Experiment 3: Mean global motion coherence thresholds for “young” and “old” participants at two dot densities (0.44 and 1.13 dots/deg2) with an aperture size of 113 deg2. Error bars = ±1 S.E.M.

Mentions: To verify the robustness of our findings, in Experiment 3 mean global motion coherence thresholds were measured for younger and older participants for two dot densities (0.44 and 1.13 dots/deg2) with a constant aperture size of 113 deg2 (Figure 4). We (Allen et al., 2010) have previously investigated the effects of age on translational motion perception using this particular aperture size and a dot density of 0.44 dots/deg2 and found no difference between young and old participants when the dot contrast was relatively high (as it is in the present study). Consistent with our previous study, when the dot density was 0.44 dots/deg2, younger and older participants’ performance was equivalent (t = −1.034, df = 16, ns). This was also the case at the higher dot density of 1.13 dots/deg2 (t = 0.601, df = 16, ns).


The ups and downs of global motion perception: a paradoxical advantage for smaller stimuli in the aging visual system.

Hutchinson CV, Ledgeway T, Allen HA - Front Aging Neurosci (2014)

Experiment 3: Mean global motion coherence thresholds for “young” and “old” participants at two dot densities (0.44 and 1.13 dots/deg2) with an aperture size of 113 deg2. Error bars = ±1 S.E.M.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4126366&req=5

Figure 4: Experiment 3: Mean global motion coherence thresholds for “young” and “old” participants at two dot densities (0.44 and 1.13 dots/deg2) with an aperture size of 113 deg2. Error bars = ±1 S.E.M.
Mentions: To verify the robustness of our findings, in Experiment 3 mean global motion coherence thresholds were measured for younger and older participants for two dot densities (0.44 and 1.13 dots/deg2) with a constant aperture size of 113 deg2 (Figure 4). We (Allen et al., 2010) have previously investigated the effects of age on translational motion perception using this particular aperture size and a dot density of 0.44 dots/deg2 and found no difference between young and old participants when the dot contrast was relatively high (as it is in the present study). Consistent with our previous study, when the dot density was 0.44 dots/deg2, younger and older participants’ performance was equivalent (t = −1.034, df = 16, ns). This was also the case at the higher dot density of 1.13 dots/deg2 (t = 0.601, df = 16, ns).

Bottom Line: We found that older adults' performance was relatively unaffected by changes in aperture size, the number and density of local elements in the display.These findings suggest that the normal (disease-free) aging process does not lead to a general decline in perceptual ability and in some cases may be visually advantageous.These include age-related changes in spatial summation, reduced cortical inhibition, neural blur and attentional resource allocation.

View Article: PubMed Central - PubMed

Affiliation: College of Medicine, Biological Sciences and Psychology, School of Psychology, University of Leicester Leicester, UK.

ABSTRACT
Recent evidence suggests that normal aging is typically accompanied by impairment in the ability to perceive the global (overall) motion of visual objects in the world. The purpose of this study was to examine the interplay between age-related changes in the ability to perceive translational global motion (up vs. down) and important factors such as the spatial extent (size) over which movement occurs and how cluttered the moving elements are (density). We used random dot kinematograms (RDKs) and measured motion coherence thresholds (% signal elements required to reliably discriminate global direction) for young and older adults. We did so as a function of the number and density of local signal elements, and the aperture area in which they were displayed. We found that older adults' performance was relatively unaffected by changes in aperture size, the number and density of local elements in the display. In young adults, performance was also insensitive to element number and density but was modulated markedly by display size, such that motion coherence thresholds decreased as aperture area increased (participants required fewer local elements to move coherently to determine the overall image direction). With the smallest apertures tested, young participants' motion coherence thresholds were considerably higher (~1.5 times worse) than those of their older counterparts. Therefore, when RDK size is relatively small, older participants were actually better than young participants at processing global motion. These findings suggest that the normal (disease-free) aging process does not lead to a general decline in perceptual ability and in some cases may be visually advantageous. The results have important implications for the understanding of the consequences of aging on visual function and a number of potential explanations are explored. These include age-related changes in spatial summation, reduced cortical inhibition, neural blur and attentional resource allocation.

No MeSH data available.


Related in: MedlinePlus