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Visual Contextual Effects of Orientation, Contrast, Flicker, and Luminance: All Are Affected by Normal Aging.

Nguyen BN, McKendrick AM - Front Aging Neurosci (2016)

Bottom Line: The perception of a visual stimulus can be markedly altered by spatial interactions between the stimulus and its surround.Such center-surround interactions in visual perception are numerous and arise from both cortical and pre-cortical neural circuitry.Here, we compare the perception of older and younger observers on a battery of tasks designed to assess such visual contextual effects.

View Article: PubMed Central - PubMed

Affiliation: Department of Optometry and Vision Sciences, University of Melbourne, Parkville VIC, Australia.

ABSTRACT
The perception of a visual stimulus can be markedly altered by spatial interactions between the stimulus and its surround. For example, a grating stimulus appears lower in contrast when surrounded by a similar pattern of higher contrast: a phenomenon known as surround suppression of perceived contrast. Such center-surround interactions in visual perception are numerous and arise from both cortical and pre-cortical neural circuitry. For example, perceptual surround suppression of luminance and flicker are predominantly mediated pre-cortically, whereas contrast and orientation suppression have strong cortical contributions. Here, we compare the perception of older and younger observers on a battery of tasks designed to assess such visual contextual effects. For all visual dimensions tested (luminance, flicker, contrast, and orientation), on average the older adults showed greater suppression of central targets than the younger adult group. The increase in suppression was consistent in magnitude across all tasks, suggesting that normal aging produces a generalized, non-specific alteration to contextual processing in vision.

No MeSH data available.


Related in: MedlinePlus

Results from the four ‘no surround’ conditions, where the stimuli were defined by (A) luminance, (B) flicker, (C) contrast, and (D) orientation. Group mean and individual data indicating the perceptual matches are plotted. The cross symbols in Panel (B) are the five individuals who could reliably match the depth of modulation of the flickering target with no surround, but could not perform the ‘surround’ version of the task because of a complete lack of flicker percept. Horizontal dotted lines indicate the veridical property of the target stimulus (A) 55 cd/m2, (B) 50% depth of modulation, (C) 40% contrast, and (D) 55° anticlockwise from horizontal meridian. Error bars are the 95% confidence limits of the mean. There was no overall difference in matching percepts between the groups across all of the tasks, F(1,34.66) = 0.79, p = 0.38.
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Figure 2: Results from the four ‘no surround’ conditions, where the stimuli were defined by (A) luminance, (B) flicker, (C) contrast, and (D) orientation. Group mean and individual data indicating the perceptual matches are plotted. The cross symbols in Panel (B) are the five individuals who could reliably match the depth of modulation of the flickering target with no surround, but could not perform the ‘surround’ version of the task because of a complete lack of flicker percept. Horizontal dotted lines indicate the veridical property of the target stimulus (A) 55 cd/m2, (B) 50% depth of modulation, (C) 40% contrast, and (D) 55° anticlockwise from horizontal meridian. Error bars are the 95% confidence limits of the mean. There was no overall difference in matching percepts between the groups across all of the tasks, F(1,34.66) = 0.79, p = 0.38.

Mentions: Statistical comparisons were performed using SPSS Version 22.0 (SPSS Inc., Chicago, IL, USA). Data were tested to determine the probability that the sample was derived from a Gaussian distribution (Kolmogorov-Smirnov test). Three participants (one younger and two older observers) could not satisfactorily match one of the four ‘no surround’ percepts, whereas data were incomplete for the flicker suppression task for five older adults, who perceived zero flicker in the ‘surround’ condition, despite being able to reliably judge the depth of modulation in the ‘no surround’ condition (cross symbols in Figure 2). To avoid removing all data from a single observer if only one data point was missing, a linear mixed effect model was employed to compare older and younger group performance across all tasks. The fixed factors of the linear mixed effect model were ‘group’ (younger, older) and ‘stimulus’ (luminance, flicker, contrast, and orientation) and the random factor was ‘participant’ to control for non-independence among repeated observations for an individual.


Visual Contextual Effects of Orientation, Contrast, Flicker, and Luminance: All Are Affected by Normal Aging.

Nguyen BN, McKendrick AM - Front Aging Neurosci (2016)

Results from the four ‘no surround’ conditions, where the stimuli were defined by (A) luminance, (B) flicker, (C) contrast, and (D) orientation. Group mean and individual data indicating the perceptual matches are plotted. The cross symbols in Panel (B) are the five individuals who could reliably match the depth of modulation of the flickering target with no surround, but could not perform the ‘surround’ version of the task because of a complete lack of flicker percept. Horizontal dotted lines indicate the veridical property of the target stimulus (A) 55 cd/m2, (B) 50% depth of modulation, (C) 40% contrast, and (D) 55° anticlockwise from horizontal meridian. Error bars are the 95% confidence limits of the mean. There was no overall difference in matching percepts between the groups across all of the tasks, F(1,34.66) = 0.79, p = 0.38.
© Copyright Policy
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC4834301&req=5

Figure 2: Results from the four ‘no surround’ conditions, where the stimuli were defined by (A) luminance, (B) flicker, (C) contrast, and (D) orientation. Group mean and individual data indicating the perceptual matches are plotted. The cross symbols in Panel (B) are the five individuals who could reliably match the depth of modulation of the flickering target with no surround, but could not perform the ‘surround’ version of the task because of a complete lack of flicker percept. Horizontal dotted lines indicate the veridical property of the target stimulus (A) 55 cd/m2, (B) 50% depth of modulation, (C) 40% contrast, and (D) 55° anticlockwise from horizontal meridian. Error bars are the 95% confidence limits of the mean. There was no overall difference in matching percepts between the groups across all of the tasks, F(1,34.66) = 0.79, p = 0.38.
Mentions: Statistical comparisons were performed using SPSS Version 22.0 (SPSS Inc., Chicago, IL, USA). Data were tested to determine the probability that the sample was derived from a Gaussian distribution (Kolmogorov-Smirnov test). Three participants (one younger and two older observers) could not satisfactorily match one of the four ‘no surround’ percepts, whereas data were incomplete for the flicker suppression task for five older adults, who perceived zero flicker in the ‘surround’ condition, despite being able to reliably judge the depth of modulation in the ‘no surround’ condition (cross symbols in Figure 2). To avoid removing all data from a single observer if only one data point was missing, a linear mixed effect model was employed to compare older and younger group performance across all tasks. The fixed factors of the linear mixed effect model were ‘group’ (younger, older) and ‘stimulus’ (luminance, flicker, contrast, and orientation) and the random factor was ‘participant’ to control for non-independence among repeated observations for an individual.

Bottom Line: The perception of a visual stimulus can be markedly altered by spatial interactions between the stimulus and its surround.Such center-surround interactions in visual perception are numerous and arise from both cortical and pre-cortical neural circuitry.Here, we compare the perception of older and younger observers on a battery of tasks designed to assess such visual contextual effects.

View Article: PubMed Central - PubMed

Affiliation: Department of Optometry and Vision Sciences, University of Melbourne, Parkville VIC, Australia.

ABSTRACT
The perception of a visual stimulus can be markedly altered by spatial interactions between the stimulus and its surround. For example, a grating stimulus appears lower in contrast when surrounded by a similar pattern of higher contrast: a phenomenon known as surround suppression of perceived contrast. Such center-surround interactions in visual perception are numerous and arise from both cortical and pre-cortical neural circuitry. For example, perceptual surround suppression of luminance and flicker are predominantly mediated pre-cortically, whereas contrast and orientation suppression have strong cortical contributions. Here, we compare the perception of older and younger observers on a battery of tasks designed to assess such visual contextual effects. For all visual dimensions tested (luminance, flicker, contrast, and orientation), on average the older adults showed greater suppression of central targets than the younger adult group. The increase in suppression was consistent in magnitude across all tasks, suggesting that normal aging produces a generalized, non-specific alteration to contextual processing in vision.

No MeSH data available.


Related in: MedlinePlus