Related Experiment Video
Updated: May 10, 2026
05:07
Using Looming Visual Stimuli to Evaluate Mouse Vision
Published on: June 13, 2019
Form and motion processing of second-order stimuli in color vision
Luis Garcia-Suarez1, Kathy T Mullen
1McGill Vision Research, Department of Ophthalmology, McGill University, Montreal, Quebec, Canada. luis.garciasuarez@plymouth.ac.uk
Journal of Vision
|June 15, 2013
Summary
Human color vision struggles with second-order form and motion processing. Achromatic stimuli are processed effectively, but chromatic stimuli rely on a third-order system, indicating limitations in second-order mechanisms for color.
Area of Science:
- Visual Neuroscience
- Human Color Vision
- Perceptual Psychology
Background:
- Second-order stimuli involve contrast modulations of a carrier.
- Understanding these mechanisms is key to comprehending visual processing.
Purpose of the Study:
- Investigate second-order form and motion processing in human color vision.
- Differentiate between second-order and third-order processing for chromatic stimuli.
Main Methods:
- Utilized static and drifting Gabor stimuli (isoluminant red-green and achromatic).
- Employed two-interval forced-choice (2IFC) for detection and identification tasks.
- Applied the pedestal paradigm to assess motion processing mechanisms.
Main Results:
- Chromatic performance lagged behind achromatic for second-order form and motion.
- Chromatic second-order form perception showed poor sensitivity (spatial cutoff 1 cycle/°, temporal cutoff 4 Hz).
- Chromatic second-order motion was limited (1-2 Hz) and impaired by pedestals, suggesting third-order processing.
Conclusions:
- A genuine second-order motion system exists for achromatic stimuli.
- Chromatic second-order motion appears to be mediated by a third-order, feature-tracking system.
- Human color vision exhibits distinct limitations in processing second-order visual information.
Related Concept Videos
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.
01:24Vision
Vision is the result of light being detected and transduced into neural signals by the retina of the eye. This information is then further analyzed and interpreted by the brain. First, light enters the front of the eye and is focused by the cornea and lens onto the retina—a thin sheet of neural tissue lining the back of the eye. Because of refraction through the convex lens of the eye, images are projected onto the retina upside-down and reversed.
01:20Anatomy of the Eyeball
The eye is a spherical, hollow structure composed of three tissue layers. The outer layer — the fibrous tunic, comprises the sclera — a white structure — and the cornea, which is transparent. The sclera encompasses some of the ocular surface, most of which is not visible. However, the 'white of the eye' is distinctively visible in humans compared to other species. The cornea, a clear covering at the front of the eye, enables light penetration. The eye's middle layer, the vascular tunic,...
01:26Visual System
Light enters the eye through the cornea, a transparent, dome-shaped surface covering the surface of the eyeball that helps to direct and focus incoming light. This light is then channeled toward the pupil, an adjustable opening whose size is controlled by the iris. The iris, a pigmented muscle, regulates the amount of light entering the eye by contracting or dilating the pupil, thereby ensuring optimal light levels for clear vision.
Once through the pupil, the light passes through the lens, a...
Once through the pupil, the light passes through the lens, a...
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...
01:20Parallel Processing
The brain processes sensory information rapidly due to parallel processing, which involves sending data across multiple neural pathways at the same time. This method allows the brain to manage various sensory qualities, such as shapes, colors, movements, and locations, all concurrently. For instance, when observing a forest landscape, the brain simultaneously processes the movement of leaves, the shapes of trees, the depth between them, and the various shades of green. This enables a quick and...