<unk>  is the ability of people who are cortically blind due to lesions in their striate cortex, also known as the primary visual cortex or V1, to respond to visual stimuli that they do not consciously see. The term was coined by Lawrence Weiskrantz and his colleagues in a paper published in Brain in 1974. A similar paper in which the discriminatory capacity of a cortically blind patient had been studied was published in Nature in 1973. The majority of studies on<unk>  are conducted on patients who are hemianopic, that is to say blind in only one half of their visual field. Following the destruction of the striate cortex, patients are asked to detect, localize, and discriminate amongst visual stimuli that are presented to their blind side, often in a forced-response or guessing situation, even though they do not necessarily consciously recognize the visual stimulus. Research shows that such blind patients may achieve a higher accuracy than would be expected from chance alone. Type 1<unk>  is the term given to this ability to guess—at levels significantly above chance—aspects of a visual stimulus (such as location or type of movement) without any conscious awareness of any stimuli. Type 2<unk>  occurs when patients claim to have a feeling that there has been a change within their blind area—e.g. movement—but that it was not a visual percept. The re-classification of<unk>  into Type 1 and Type 2 was made after it was shown that the most celebrated<unk>  patient, GY, was in fact usually conscious of stimuli presented to his blind field if the stimuli had certain specific characteristics, namely were of high contrast and moved fast, at speeds in excess of 20 degrees per second. In fact, in the aftermath of the First World War, a neurologist, George Riddoch, had described patients who had been blinded by gunshot wounds to V1, who could not see stationary objects but who were, as he reported, "conscious" of seeing moving objects in their blind field. It is for this reason that the phenomenon has more recently also been called the Riddoch syndrome. Since then it has become apparent that such subjects can also become aware of visual stimuli belonging to other visual domains, such as color and luminance, when presented to their blind fields. The ability of such hemianopic subjects to become consciously aware of stimuli presented to their blind field is also commonly referred to as "residual" or "degraded" vision.<unk> , as originally defined, challenged the common belief that perceptions must enter consciousness to affect our behavior, by showing that our behavior can be guided by sensory information of which we have no conscious awareness. Since the demonstration that blind patients can experience some visual stimuli consciously, and the consequent redefinition of<unk>  in Type 1 and Type 2, there has been a more nuanced view of it. It may be thought of as a converse of the form of anosognosia known as Anton–Babinski syndrome, in which there is full cortical blindness along with the confabulation of visual experience.
Blindsight
Underwater vision
Sharsheret 
Far-sightedness
Tunnel vision
Hot flash
Itch
Mesopic vision