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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 ‘surround’ conditions, where center–surround stimuli were defined by (A) luminance, (B) flicker, (C) contrast, and (D) orientation. Group mean and individual suppression indices (1 – PSE ‘surround’/PSE ‘no surround’) are plotted, where a positive suppression index indicates suppression, a negative index indicates facilitation, and an index of 0 indicates no effect of the surround. Error bars are the 95% confidence limits of the mean. PSE, point of subjective equality. The two groups were significantly different from each other across all tasks, F(1,36.40) = 22.02, p < 0.001.
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Figure 3: Results from the four ‘surround’ conditions, where center–surround stimuli were defined by (A) luminance, (B) flicker, (C) contrast, and (D) orientation. Group mean and individual suppression indices (1 – PSE ‘surround’/PSE ‘no surround’) are plotted, where a positive suppression index indicates suppression, a negative index indicates facilitation, and an index of 0 indicates no effect of the surround. Error bars are the 95% confidence limits of the mean. PSE, point of subjective equality. The two groups were significantly different from each other across all tasks, F(1,36.40) = 22.02, p < 0.001.

Mentions: Next, we used a separate mixed model analysis to compare the effect of introducing a surround by calculating suppression indices, as illustrated in Figure 3. The higher the suppression index, the greater the strength of suppression. The older group showed increased suppression relative to the younger participants for all stimuli [main effect of group: F(1,36.40) = 22.02, p < 0.001]. The difference in group performance was consistent across stimuli [group × stimulus interaction: F(3,99.17) = 1.37, p = 0.26]. Effect sizes (Cohen’s d, Eq. 2) were calculated to compare the magnitude of increased suppression in the older group, relative to the control group:


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 ‘surround’ conditions, where center–surround stimuli were defined by (A) luminance, (B) flicker, (C) contrast, and (D) orientation. Group mean and individual suppression indices (1 – PSE ‘surround’/PSE ‘no surround’) are plotted, where a positive suppression index indicates suppression, a negative index indicates facilitation, and an index of 0 indicates no effect of the surround. Error bars are the 95% confidence limits of the mean. PSE, point of subjective equality. The two groups were significantly different from each other across all tasks, F(1,36.40) = 22.02, p < 0.001.
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Related In: Results  -  Collection

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getmorefigures.php?uid=PMC4834301&req=5

Figure 3: Results from the four ‘surround’ conditions, where center–surround stimuli were defined by (A) luminance, (B) flicker, (C) contrast, and (D) orientation. Group mean and individual suppression indices (1 – PSE ‘surround’/PSE ‘no surround’) are plotted, where a positive suppression index indicates suppression, a negative index indicates facilitation, and an index of 0 indicates no effect of the surround. Error bars are the 95% confidence limits of the mean. PSE, point of subjective equality. The two groups were significantly different from each other across all tasks, F(1,36.40) = 22.02, p < 0.001.
Mentions: Next, we used a separate mixed model analysis to compare the effect of introducing a surround by calculating suppression indices, as illustrated in Figure 3. The higher the suppression index, the greater the strength of suppression. The older group showed increased suppression relative to the younger participants for all stimuli [main effect of group: F(1,36.40) = 22.02, p < 0.001]. The difference in group performance was consistent across stimuli [group × stimulus interaction: F(3,99.17) = 1.37, p = 0.26]. Effect sizes (Cohen’s d, Eq. 2) were calculated to compare the magnitude of increased suppression in the older group, relative to the control group:

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