Looking with the Head and Eyes (Gibson, 1979, Chapter 12)

In this chapter, Gibson places head and eye movements on an ecological footing, and makes them the activity of a distributed perceptual system (c.f. Gibson, 1966) who's job it is to look around. 

We have to look around because our heads get in the way of our eyes. Even animals with eyes on the side have this problem, but for animals with front-facing eyes over half the optic array that is ambient to a point of observation is occluded by the head (which of course also specifies the presence of the self). Looking around is about reversing that occlusion and revealing things as required. 

The Discovery of the Occluding Edge and Its Implications for Perception (Gibson, 1979, Chapter 11)

Gibson introduced us to the notion of occlusion in Chapter 5. Occlusion is when one surface is progressively covered up by another surface, and the details of how optical texture is deleted specifies the occluding edge and the fact that occlusion is happening. In this chapter, Gibson details the radical implications of this fact of the optic array for theories of perception. Most importantly, given occlusion, vision cannot be based on images, series of images, or perspective structure, and it is not limited to working when sensations fall on the retina. Vision is a process that extends back and forwards in time, and this is enabled by information.