Related Experiment Video
Updated: Jun 20, 2026
04:43
Visualizing Visual Adaptation
Published on: April 24, 2017
Aging alters surround modulation of perceived contrast
Renee Karas1, Allison M McKendrick
1Department of Optometry and Vision Science, The University of Melbourne, VIC, Australia. r.karas@pgrad.unimelb.edu.au
Journal of Vision
|September 18, 2009
Summary
Older adults showed increased sensitivity to surround effects in a contrast discrimination task, contrary to predictions of reduced visual inhibition with aging. This suggests potential age-related changes in how the brain processes visual information.
Area of Science:
- Vision science
- Neuroscience
- Gerontology
Background:
- Visual functions often decline with age.
- Counter-intuitively, older adults may process motion direction faster than younger adults.
- This has been hypothesized to result from reduced cortical inhibition in the aging visual system.
Purpose of the Study:
- To investigate the perceptual effects of aging on center-surround suppression in the human visual system.
- To test the hypothesis that older adults exhibit reduced center-surround suppression due to decreased cortical inhibition.
Main Methods:
- Utilized a center-surround contrast discrimination task (Chubb contrast illusion).
- Compared performance between healthy older and younger adult observers.
- Measured the impact of surround modulation on perceived contrast.
Main Results:
- Older observers demonstrated significantly greater alteration of perceived contrast by surround modulation compared to younger observers.
- This finding contradicts the prediction of reduced center-surround suppression in the elderly.
- The results indicate that aging may affect visual processing differently than previously hypothesized.
Conclusions:
- The data does not support the hypothesis of reduced cortical inhibition manifesting as less center-surround suppression in older adults.
- An alternative explanation involves decreased brightness induction in the elderly, possibly due to disrupted neural synchronization.
- Aging's impact on visual perception, particularly concerning surround effects, requires further investigation.
More Related Videos
Related Concept Videos
01:12Perceptual Constancy
Perceptual constancy is the ability to recognize that objects remain consistent and unchanged even when their appearance varies due to changes in sensory input. There are four main types of perceptual constancy: size constancy, shape constancy, color constancy, and brightness constancy.
Size constancy is the recognition that an object remains the same size, even when its image on the retina changes. For instance, a bus is perceived to be large enough to carry people, even if it looks tiny from...
Size constancy is the recognition that an object remains the same size, even when its image on the retina changes. For instance, a bus is perceived to be large enough to carry people, even if it looks tiny from...
01:25Factors Affecting Perception
Perception is influenced by perceptual set, context, motivation, and emotion. Perceptual set, or perceptual expectancy, refers to the tendency to perceive things in a particular way, influenced by previous experiences and expectations. This phenomenon affects the interpretation of stimuli, creating a set of mental tendencies and assumptions that impact sensory perceptions of sound, taste, touch, and sight.
An illustrative example of a perceptual set is the scenario where an airline pilot told...
An illustrative example of a perceptual set is the scenario where an airline pilot told...
01:24Color Vision
Color perception begins in the retina, the light-sensitive layer at the back of the eye. Two main theories explain how colors are seen: the trichromatic theory and the opponent-process theory. The trichromatic theory, proposed by Thomas Young in 1802 and extended by Hermann von Helmholtz in 1852, suggests that color vision is based on three types of cone receptors in the retina. These cones are sensitive to different but overlapping ranges of wavelengths corresponding to red, blue, and green.
01:15Depth Perception and Spatial Vision
Depth perception is the ability to perceive objects three-dimensionally. It relies on two types of cues: binocular and monocular. Binocular cues depend on the combination of images from both eyes and how the eyes work together. Since the eyes are in slightly different positions, each eye captures a slightly different image. This disparity between images, known as binocular disparity, helps the brain interpret depth. When the brain compares these images, it determines the distance to an object.
01:22Photoreceptors and Visual Pathways
At the molecular level, visual signals trigger transformations in photopigment molecules, resulting in changes in the photoreceptor cell's membrane potential. The photon's energy level is denoted by its wavelength, with each specific wavelength of visible light associated with a distinct color. The spectral range of visible light, classified as electromagnetic radiation, spans from 380 to 720 nm. Electromagnetic radiation wavelengths exceeding 720 nm fall under the infrared category, whereas...
01:21Gestalt Principles of Perception
Gestalt principles provide a framework for understanding how humans perceive objects as unified wholes within their context. These principles are essential in explaining the cognitive processes that make sense of complex visual stimuli by organizing them into coherent groups. One fundamental principle is proximity, which posits that objects located close to each other are perceived as a collective group. For instance, when dots are positioned near one another, the visual system interprets them...