Following certain kinds of brain lesions, patients report an inability to see objects, but if pressed to guess at their location they display a capacity to point at them with reasonable accuracy. The phenomenon, called "blindsight", is one of the more dramatic of a number of lines of evidence suggesting that being aware of doing something is distinguishable from doing something, that areas of the brain underlying the experience of doing at least some things are distinct from those needed to actually do those things.
Such a dissociation has a number of interesting implications. In a general sense, it provides evidence for the existence and significance of an "unconscious" as a contributor to human behavior (and hence for consciousness as distinctive part rather than synomous with the totality of brain function). Blindsight also provides a possible explanation for some experiences of "magical" or "transcendent" abilities, at least insofar as these relate to performance characteristics of individuals for which the individuals themselves cannot account. A dissociation between unconscious and conscious processing is also of significance in an educational context, since the two sorts of processing may acquire, process, and make use of experiences in different ways.
Blindsight - the ability to respond appropriately to visual inputs while lacking the feeling of having seen them - might be something which only occurs in cases of brain damage, but seems much more likely to be a significant phenomenon of intact brain function as well. Indeed, it seems likely that blindsight (and similar phenomena in other spheres) is an important ingredient of of a variety of activities where one wants to move quickly and appropriately, without "thinking about it".
The display below is designed to allow you to try and experience blindsight yourself, in a simple and controllable situation. First you will need to set some parameters. Stare at the cross in the middle of the screen and click the Try button. A target will briefly appear above and to the left of the cross in the center of the screen. Sliders control the duration of the target, as well as its size and how much lighter or darker the target is in comparison to the grey background. Move the speed slider to find the shortest duration target which you can reliably see on every trial (this will vary somewhat depending on your equipment). Then reduce size and/or contrast to yield a target which you can just detect (this can be done with a number of different combinations).
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