the "input-output picture," where the idea is that on this picture, perception is input from the world to the mind, action is output from the mind to the world, and cognition and consciousness is what happens inside the head to relate those two. In my view, this is all wrong. We need to get rid od the input-output picture altogether. This is what I argued in my 2004 book Action in Perception . To see is to attain a certain kind of skillful access to the world. It is, for that reason, an essentially action-dependent kind of thing -- by which I don't merely mean that we need to move in order to see, but by which I mean that, in order to see, we need to understand what happens to us visually when we move -- seeing is a kind of knowledge of the sensory effects of movement. If I approach an object, it looms in my visual field. If I blink, the sensory stimulation from the object is disrupted. If I walk around an object, its profile transforms. In these and other ways movement produces sensory change. I hold that seeing just is an activity of exploring the world, making use of that kind of sensorimotor understanding. The world -- three-dimensional objects arrayed in space, colors, shapes, etc. -- only comes into focus for perception given the perceiver's ability to exercise this kind of practical sensorimotor understanding. There are very straightforward ways of testing this. If I put