Stereoscopic vision: What’s the first step?

Backus, B.T. (2000) Stereoscopic vision: What’s the first step? Current Biology 10 R701-R703

Abstract
Neurons in primary visual cortex respond to binocular disparity, the raw material of stereoscopic
depth perception. Although these neurons are probably essential to depth perception, a recent study has shown that they are unable to compute depth itself.