Vision and Blindsight Essay -- Biology Essays Research Papers

Vision and Blindsight Implications Regarding Consciousness Vision-- receiving and interpreting light signals from the environment in order to form an image in one's mind-- is an incredibly complex process. Somehow signals from photoreceptors located in the eye are converted into the conscious experience of sight. Of all the aspects of vision, perhaps the most difficult for us to comprehend scientifically is this notion of consciousness. Somehow the brain interprets light waves hitting the retina so that we are visually aware of our surroundings. While the mechanism of signal transduction from the photoreceptor through the visual cortex has been extensively elucidated, science has difficulty dealing with the phenomena of consciousness and awareness, especially on a reductionist level. A recent neurobiological approach to understanding consciousness, at least on a perceptual level, has involved the study of the phenomenon of blindsight. Damage to areas of the visual cortex often result in complete or partial blindness. Although the eye itself is undamaged, patients report an inability to detect any light input in part of (or the entire) visual field. However, experiments regularly show that somehow, visual cues are processed. Visual inputs presented to the blind field affect the patient's response to stimulus in the normal visual field. Reaction times to stimuli are affected as well as the interpretation of the stimuli. A visual cues presented in the blind field may suggest a certain interpretation of an ambiguous stimuli. For example, the interpretation of the word "bank", presented as an auditory cue, differs depending on whether the word "river" or "money" is presented to the blind field, even though the patient does not... ...Linked%20Pages/Physiol/Cortex.html 3) Visual Processing Streams http://mitpress.mit.edu/MITECS/work/goodale_r.html 4) Consciousness, Neurobiology of http://mitpress.mit.edu/MITECS/work/koch_r.html 5) Pattern of neuronal activity associated with conscious and unconscious processing of visual signals, Sahraie, et al. http://www.pnas.org/cgi/content/full/94/17/9406?terms=consciousness&searchqstr=tyear:1997!fyear:1996!fmonth:Nov!tmonth:Nov!tdatedef:11+November+1997!fdatedef:12+November+1996!hits:10!fulltext:consciousness!sendit:Search 6) The Problem of Consciousness Crick and Koch http://www.unomaha.edu/~spaige/crick-ko.htm#blindsight 7) Co nsciousness http://www.duke.edu/~kellogg/Classes/Mentation/Issue%201/Marchiano.htm 8) On a Confusion About a Function of Consciousness. Block, Ned ftp://ftp.princeton.edu/pub/harnad/BBS/.WWW/bbs.block.html