was to say it was in the lower part, and vice versa. he was able to misstate, as requested, in his left visual field (with normal conscious vision); but he tended to fail in the task—to state the location correctly—when the stimulus was in his blindsight (right) visual field. > this failure rate worsened when the stimulus was clearer, indicating that failure was not simply due to unreliability of blindsight. case studies researchers applied the same type of tests that were used to study blindsight in animals to a patient referred to as "db". the normal techniques used to assess visual acuity in humans involved asking them to verbally describe some visually recognizable aspect of an object or objects. db was given forced-choice tasks to complete instead. the results of db's guesses showed that db was able to determine shape and detect movement at some unconscious level, despite not being visually aware of this. db themselves chalked up the accuracy of their guesses to be merely coincidental. the discovery of the condition known as blindsight raised questions about how different types of visual information, even unconscious information, may be affected and sometimes even unaffected by damage to different areas of the visual cortex. previous studies had already demonstrated that even without conscious awareness of visual stimuli, humans could still determine certain visual features such as presence in the visual field, shape, orientation and movement. but, in a newer study evidence showed that if damage to the visual cortex occurs in areas above the primary visual cortex, the conscious awareness of visual stimuli itself is not damaged. blindsight shows that even when the primary visual cortex is damaged or removed a person can still perform actions guided by unconscious visual information. despite damage occurring in the area necessary for conscious awareness of visual information, other functions of the processing of these visual percepts are still available to the individual. the same also goes for damage to other areas of the visual cortex. if an area of the cortex that is responsible for a certain function is damaged, it will only result in the loss of that particular function or aspect, functions that other parts of the visual cortex are responsible for remain intact. alexander and cowey investigated how contrasting stimuli brightness affects blindsight patients' ability to discern movement. prior studies have already shown that blindsight patients are able to detect motion even though they claim they do not see any visual percepts in their blind fields. the study subjects were two patients who suffered from hemianopsia—blindness in more than half of their visual field. both subjects had displayed the ability to accurately determine the presence of visual stimuli in their blind hemifields without acknowledging an actual visual percept previously. to test the effect of brightness on the subject's ability to determine motion they used a white background with a series of colored dots. the contrast of the brightness of the dots compared to the white background was altered in each trial to determine if the participants performed better or worse when there was a larger discrepancy in brightness or not. the subjects focused on the display for two equal length time intervals and where asked whether they thought the dots were moving during the first or the second time interval. when the contrast in brightness between the background and the dots was higher, both of the subjects could discern motion more accurately than they would have statistically through guesswork. however, one subject was not able to accurately determine whether or not blue dots were moving regardless of the brightness contrast, but he/she was able to do so with every other color dot. when the contrast was highest subjects were able to tell whether or not the dots were moving with very high rates of accuracy. even when the dots were white, but still of a different brightness from the background, subjects could still determine whether they were moving. but, regardless of the dots' color, subjects could not tell when they were in motion when the white background and the dots were of similar brightness. kentridge, heywood, and weiskrantz used the phenomenon of blindsight to investigate the connection between visual attention and visual awareness. they wanted to see if their subject—who exhibited blindsight in other studies—could react more quickly when their attention was cued without the ability to be visually aware of it. the researchers aimed to show that being conscious of a stimulus and paying attention to it was not the same thing. to test the relationship between attention and awareness, they had the participant try to determine where a target was and whether it was oriented horizontally or vertically on a computer screen. the target line would appear at one of two different locations and would be oriented in one of two directions. before the target would appear an arrow would become visible on the screen, sometimes pointing to the correct position of the target line and less frequently not. this arrow was the cue for the subject. the participant would press a key to indicate whether the line was horizontal or vertical, and could then also indicate to an observer whether or not he/she actually had a feeling that any object was there or not—even if they couldn't see anything. the participant was able to accurately determine the orientation of the line when the target was cued by an arrow before the appearance of the target, even though these visual stimuli did not equal awareness in the subject who had no vision in that area of his/her visual field. the study showed that even without the ability to be visually aware of a stimulus the participant could still focus his/her attention on this object. in 2003, a patient known as "tn" lost use of his primary visual cortex, area v1. he had two successive strokes, which knocked out the region in both his left and right hemispheres. after his strokes, ordinary tests of tn's sight turned up nothing. he could not even detect large objects moving right in front of his eyes. researchers eventually began to notice that tn exhibited signs of blindsight and in 2008 decided to test their theory. they took tn into a hallway and asked him to walk through it without using the cane he always carried after having the strokes. tn was not aware at the time, but the researchers had placed various obstacles in the hallway to test if he could avoid them without conscious use of his sight. to the researchers' delight, he moved around every obstacle with ease, at one point even pressing himself up against the wall to squeeze past a trashcan placed in his way. after navigating through the hallway, tn reported that he was just walking the way he wanted to, not because he knew anything was there. in another case study, a girl brought her grandfather in to see a neuropsychologist. the girl's grandfather, mr. j., had suffered a stroke that had left him completely blind apart from a tiny spot in the middle of his visual field. the neuropsychologist, dr. m., performed an exercise with him. the doctor helped mr. j. to a chair, had him sit down, and then asked to borrow his cane. the doctor then asked, "mr. j., please look straight ahead. keep looking that way, and don't move your eyes or turn your head. i know that you can see a little bit straight ahead of you, and i don't want you to use that piece of vision for what i'm going to ask you to do. fine. now, i'd like you to reach out with your right hand point to what i'm holding." mr. j. then replied, "but i don't see anything—i'm blind!" the doctor then said, "i know, but please try, anyway." mr. j then shrugged and pointed, and was surprised when his finger encountered the end of the cane which the doctor was pointing toward him. after this, mr. j. said that "it was just luck". the doctor then turned the cane around so that the handle side was pointing towards mr. j. he then asked for mr. j. to grab hold of the cane. mr. j. reached out with an open hand and grabbed hold of the cane. after this, the doctor said, "good. now put your hand down, please." the doctor then rotated the cane 90 degrees, so that the handle was oriented vertically. the doctor then asked mr. j. to reach for the cane again. mr. j. did this, turning his wrist so that his hand matched the orientation of the handle. this case study shows that, although (on a conscious level) mr. j. was completely unaware of any visual abilities that he may have had, he was able to orient his grabbing motions as if he had no visual impairments. brain regions involved visual processing in the brain goes through a series of stages. destruction of the primary visual cortex leads to blindness in the part of the visual field that corresponds to the damaged cortical representation. the area of blindness – known as a scotoma – is in the visual field opposite the damaged hemisphere and can vary from a small area up to the entire hemifield. visual processing occurs in the brain in a hierarchical series of stages (with much crosstalk and feedback between areas). the route from the retina through v1 is not the only visual pathway into the cortex, though it is by far the largest; it is commonly thought that the residual performance of people exhibiting blindsight is due to preserved pathways into the extrastriate cortex that bypass v1. however both physiological evidence in monkeys and behavioral and imaging evidence in humans shows that activity in these extrastriate areas, and especially in v5, is apparently sufficient to support visual awareness in the absence of v1. to put it in a more complex way, recent physiological findings suggest that visual processing takes place along several independent, parallel pathways. one system processes information about shape, one about color, and one about movement, location and spatial organization. this information moves through an area of the brain called the lateral geniculate nucleus, located in the thalamus, and on to be processed in the primary visual cortex, area v1 (also known as the striate cortex because of its striped appearance). people with damage to v1 report no conscious vision, no visual imagery, and no visual images in their dreams. however, some of these people still experience the blindsight phenomenon, though this too is controversial, with some studies showing a limited amount of consciousness without v1 or projections relating to it. the superior colliculus and prefrontal cortex also have a major role in awareness of a visual stimulus. lateral geniculate nucleus main article: lateral geniculate nucleus mosby's dictionary of medicine, nursing & health professions defines the lgn as "one of two elevations of the lateral posterior thalamus receiving visual impulses from the retina via the optic nerves and tracts and relaying the impulses to the calcarine (visual) cortex". what is seen in the left and right visual field is taken in by each eye and brought back to the optic disc via the nerve fibres of the retina. from the optic disc, visual information travels through the optic nerve and into the optic chiasm. visual information then enters the optic tract and travels to four different areas of the brain including the superior colliculus, pretectum of the mid brain, the suprachiasmatic nucleus of the hypothalamus, and the lateral geniculate nucleus (lgn). most axons from the lgn will then travel to the primary visual cortex. injury to the primary visual cortex, including lesions and other trauma, leads to the loss of visual experience. however, the residual vision that is left cannot be attributed to v1. according to schmid et al., "thalamic lateral geniculate nucleus has a causal role in v1-independent processing of visual information". this information was found through experiments using fmri during activation and inactivation of the lgn and the contribution the lgn has on visual experience in monkeys with a v1 lesion. these researchers concluded that the magnocellular system of the lgn is less affected by the removal of v1, which suggests that it is because of this system in the lgn that