Biomaterial Database

The orientation specificity of two visual after-effects. 1971

C Blakemore, and J Nachmias

1. Inspection of a high-contrast adapting grating produces two visual after-effects: (a) the contrast threshold is raised for test gratings of similar spatial frequency to that of the adapting pattern and (b) the apparent spatial frequency of test gratings shifts away from that of the adapting grating-higher frequencies seem higher and lower ones lower than they really are.2. Both after-effects are orientation-specific. A horizontal adapting grating influences neither the threshold nor the apparent spatial frequency of vertical test gratings.3. The magnitude of the two after-effects was measured with vertical test gratings as a function of (a) tilt of a high-contrast adapting grating and (b) contrast of a vertical adapting grating.4. At all frequencies of the test grating, the decline of both after-effects produced by an increase in tilt of approximately 6(3/4) degrees could be matched by a reduction in contrast by a factor of 2.5. We take this as evidence for a common neural origin for these two visual phenomena.

UI	MeSH Term	Description	Entries
D008297	Male		Males
D008722	Methods	A series of steps taken in order to conduct research.	Techniques,Methodological Studies,Methodological Study,Procedures,Studies, Methodological,Study, Methodological,Method,Procedure,Technique
D009949	Orientation	Awareness of oneself in relation to time, place and person.	Cognitive Orientation,Mental Orientation,Psychological Orientation,Cognitive Orientations,Mental Orientations,Orientation, Cognitive,Orientation, Mental,Orientation, Psychological,Orientations,Orientations, Cognitive,Orientations, Mental,Orientations, Psychological,Psychological Orientations
D005556	Form Perception	The sensory discrimination of a pattern, shape, or outline.	Contour Perception,Contour Perceptions,Form Perceptions,Perception, Contour,Perception, Form,Perceptions, Contour,Perceptions, Form
D006801	Humans	Members of the species Homo sapiens.	Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D000360	Afterimage	Continuation of visual impression after cessation of stimuli causing the original image.	Afterimages
D014787	Vision Tests	A series of tests used to assess various functions of the eyes.	Test, Vision,Tests, Vision,Vision Test
D014792	Visual Acuity	Clarity or sharpness of OCULAR VISION or the ability of the eye to see fine details. Visual acuity depends on the functions of RETINA, neuronal transmission, and the interpretative ability of the brain. Normal visual acuity is expressed as 20/20 indicating that one can see at 20 feet what should normally be seen at that distance. Visual acuity can also be influenced by brightness, color, and contrast.	Acuities, Visual,Acuity, Visual,Visual Acuities
D014796	Visual Perception	The selecting and organizing of visual stimuli based on the individual's past experience.	Visual Processing,Perception, Visual,Processing, Visual