Mind's eye

Overview
The phrase "mind's eye" refers to the human ability for visual perception, imagination, visualization, and memory, or, in other words, one's ability to "see" things with the mind.

Physical basis
The biological foundation of the mind's eye is not fully understood. fMRI studies have shown that the lateral geniculate nucleus and the V1 area of the visual cortex are activated during mental imagery tasks. Ratey writes: "The visual pathway is not a one-way street. Higher areas of the brain can also send visual input back to neurons in lower areas of the visual cortex... As humans, we have the ability to see with the mind's eye -to have a perceptual experience in the absence of visual input. For example, PET scans have shown that when subjects, seated in a room, imagine they are at their front door starting to walk either to the left or right, activation begins in the visual association cortex, the parietal cortex, and the prefrontal cortex - all higher cognitive processing centers of the brain." Not all humans have this ability. With eyes closed, some humans report that they can visualize, or imagine, detailed scenery that is not just a memory. Others however, cannot. These humans report that while details of visual memories can be recalled (with eyes open), the images themselves cannot be brought up, even with eyes closed. Users of hallucinogenic drugs report seeing images with eyes closed, however the images are random and hard to control, and may interfere with normal consciousness.

Philosophy
The use of the phrase mind's eye does not imply that there is a single or unitary place in the mind or brain where visual consciousness occurs. Various philosophers have criticized this view, Daniel Dennett being one of the best-known. However, others, such as Johnjoe McFadden of the University of Surrey in the UK and the New Zealand-based neurobiologist Susan Pockett, have proposed that the brain's electromagnetic field is consciousness itself, thus causing the perception of a unitary location.