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Blind spot
Blind spot The location where optic nerve fibers leave the retina. This area has no photoreceptors and therefore no visual input. The cortex appears to fill-in this missing information so we are not conscious of the blind spot.
RELATED TERMS--------------------------------------
Nerve
Tissue that conveys sensation, temperature, position information to the brain.
Retina
A membrane lining the inside of the back of the eye that contains light-sensitive nerve cells that convert focused light into nerve impulses, making vision possible.
Cortex
The outer layer of the cerebrum, densely packed with nerve cells.
Conscious
Mentally awake and aware. Knowing what one is doing and why.
Blind
1. Unable to see. Without part or all of the sense of sight.2. In a clinical trial, not to know the treatment given or received. The participant is not told whether they are in the experimental or control arm of the study. Also called masked.
SIMILAR TERMS--------------------------------------
Blind
1. Unable to see. Without part or all of the sense of sight.2. In a clinical trial, not to know the treatment given or received. The participant is not told whether they are in the experimental or control arm of the study. Also called masked.
Blind review
The checking and assessment of data during the period of time between trial completion (the last observation on the last subject) and the breaking of the blind, for the purpose of finalising the planned analysis.
Blind study
One in which the subject or the investigator (or both) are unaware of what trial product a subject is taking. See also double-blind study, single-blind study, triple-blind study.
Blinded medications
Products that appear identical in size, shape, colour, flavour, and other attributes to make it very difficult for subjects and investigators to determine which medication is being administered.
Blinded study
A study done in such a way that the patients or subjects do not know (is blinded as to) what treatment they are receiving to ensure that the results are not affected by a placebo effect (the power of suggestion).
Blinding/masking
A procedure in which one or more parties to the trial are kept unaware of the treatment assignments. Single-blinding usually refers to the subject(s) being unaware, and doubleblinding usually refers to the subject(s), investigators, monitor, and, in some cases, data analyst(s) being unaware of the treatment assignments.
Blindness
Legal blindness is defined as: 1) visual acuity of 20/200 (only being able to see the big E on the eye chart) or less in the best eye even with the eyes corrected by glasses or contact lenses; or, 2) The peripheral visual field is reduced to 20 degrees of visual angle or less. Twenty degrees of visual angle is about the size of a one foot ruler held at arms length.
Blindness, legal
See: Legal blindness.
Blindness, night
Impaired vision in dim light and in the dark, due to impaired function of specific vision cells (namely, the rods) in the retina.
Blindsight
A phenomenon reported in individuals suffering from cortical blindness (i.e. damage to the primary visual cortex resulting in blindness). Individuals with blindsight report that they are unable to see, yet under forced choice conditions are able to indicate the presence and location of visually presented objects.
Blink rate
The number of times per minute that the eyelid automatically closes -- normally 10 to 30 per minute.
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Binocular rivalry
Occurs when the two eyes are presented with different stimuli. Instead of seeing a summation of the two images, our perception switches from one image to the other.
Binocular zone
The central region of the visual field from which light enter both eyes.
Binoptic stimulation
When the same image is presented to each eye.
Bioluminescence
The emission of light by organisms.
Bipolar cell
Key interneurons in the retina. Antagonistic center-surround receptive field organization. Makes excitatory connections to ganglion cells.
Blind spot
Blindsight
A phenomenon reported in individuals suffering from cortical blindness (i.e. damage to the primary visual cortex resulting in blindness). Individuals with blindsight report that they are unable to see, yet under forced choice conditions are able to indicate the presence and location of visually presented objects.
Block artifacts
Visual artifacts created when an image compressed with an algorithm using block coding is reconstructed.
Block coding
Any image processing technique which begins by subdividing the image into blocks.
Bregman-Kanizsa display
A display which suggests that the presence of visible occluders permits amodal completion which aid figure-ground segmentation and object recognition.
Border contrast
A localized contrast effect which is limited to the border immediately adjecent to the contrast discontinuity.
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