Biomaterial Database

Displacement thresholds for motion detection under conditions of chromatic adaptation. 1985

J L Barbur, and J E Saunders

The smallest, continuous target displacement which is sufficient to cause a sensation of movement was measured under conditions of chromatic adaptation. The experiments were carried out for test target and background field wavelengths which selectively isolate the activity of the colour mechanisms of the human eye. The results show that, when target detection is largely mediated by the red or green colour mechanism, a target displacement of 2-3' in the foveal region is sufficient to cause a reliable sensation of movement. These displacement thresholds show only a small change as a function of target contrast or background retinal illuminance level. Similar results were obtained when the colour of the test target was the same as that of the background field (e.g. green, yellow or red), when no attempt was made to isolate a single colour mechanism. Test target and background wavelengths which isolate the activity of the blue colour mechanism yield displacement thresholds in the range 5-7' and show a stronger dependence on target contrast and background retinal illuminance level. The experiments were repeated at several eccentricities and the results show that, for a test target and background field of the same colour and under conditions which isolate the green or red spectral response mechanism, the minimum target displacement required for motion detection appears to increase in a manner similar to the centre-width receptive-field size of broad-band, centre--surround transient neurons in the rhesus monkey retina [De Monasterio and Gouras (1975) J. Physiol., Lond. 251, 167-195].(ABSTRACT TRUNCATED AT 250 WORDS)

UI	MeSH Term	Description	Entries
D009039	Motion Perception	The real or apparent movement of objects through the visual field.	Movement Perception,Perception, Motion,Perception, Movement
D012160	Retina	The ten-layered nervous tissue membrane of the eye. It is continuous with the OPTIC NERVE and receives images of external objects and transmits visual impulses to the brain. Its outer surface is in contact with the CHOROID and the inner surface with the VITREOUS BODY. The outer-most layer is pigmented, whereas the inner nine layers are transparent.	Ora Serrata
D003118	Color Perception	Mental processing of chromatic signals (COLOR VISION) from the eye by the VISUAL CORTEX where they are converted into symbolic representations. Color perception involves numerous neurons, and is influenced not only by the distribution of wavelengths from the viewed object, but also by its background color and brightness contrast at its boundary.	Color Perceptions,Perception, Color,Perceptions, Color
D005584	Fovea Centralis	An area approximately 1.5 millimeters in diameter within the macula lutea where the retina thins out greatly because of the oblique shifting of all layers except the pigment epithelium layer. It includes the sloping walls of the fovea (clivus) and contains a few rods in its periphery. In its center (foveola) are the cones most adapted to yield high visual acuity, each cone being connected to only one ganglion cell. (Cline et al., Dictionary of Visual Science, 4th ed)
D006801	Humans	Members of the species Homo sapiens.	Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D000221	Adaptation, Ocular	The adjustment of the eye to variations in the intensity of light. Light adaptation is the adjustment of the eye when the light threshold is increased; DARK ADAPTATION when the light is greatly reduced. (From Cline et al., Dictionary of Visual Science, 4th ed)	Light Adaptation,Adaptation, Light,Adaptations, Light,Adaptations, Ocular,Light Adaptations,Ocular Adaptation,Ocular Adaptations
D013997	Time Factors	Elements of limited time intervals, contributing to particular results or situations.	Time Series,Factor, Time,Time Factor
D014787	Vision Tests	A series of tests used to assess various functions of the eyes.	Test, Vision,Tests, Vision,Vision Test