In this post over at Science and Consciousness Review, Stan Franklin discusses how the dorsal, or “where” stream of visual perception is unconsciousness. In contrast to the ventral stream, which is responsible for the “what”, or object recognition, the dorsal stream is involved with spatial awareness for actions such as grasping.
Franklin cites work from Goodale and Milner that studied a patient with an impaired dorsal stream. After careful experimentation, Goodale and Milner concluded that the dorsal stream is unconscious. Normally, I do not like discussing perception in terms of the conscious/unconscious dichotomy, but I though this conclusion was interesting because of its implications for Shaun Gallagher’s preconscious body schema, that I discussed in this previous post. This body schema is a system of sensory-motor capacities that is responsible for such pre-reflective activities as walking, keeping upright posture, and other motor actions that we do more or less “unconsciously” such as appropriately molding our grip to reach an object. So, with respect with the unconscious dorsal processing Franklin was discussing, I think the body schema is an appropriate theoretical construction that fits the evidence.