What is striking is the huge amount of brain contributing to vision, giving immense added value to the images of the eyes. Where does this extra richness for vision come from? By some authorities it is simply denied-they see perception as passive acceptance of what is out there, as a window facing the world. But this does not begin to explain how we see objects from the sketchy images of the eyes, even from sparse lines and crude dots of seemingly inadequate pictures. In ideal conditions, object perception is far richer than any possible images in the eyes. The added value must come from dynamic brain processes, employing knowledge stored from the past, to see the present and predict the immediate future. Prediction has immense survival value. It not only makes fast games possible in spite of the physiological signal delays from eye to brain, and brain to hand. Anticipating dangers and potential rewards is essential for survival¬made possible by buying time from seeing objects distant in space. (Gregory, 1997, p. 2).I am assuming that EPists are among the "authorities" here. I think the perception as passive idea comes from the talk of direct pickup; there is no activity of inference or computing. For EPists the activity of perception is moving the eyes and body around, but that thereafter the visual system just lets the information seep in.
For Gregory, there is the activity of moving the eyes and body (I assume he's ok with the movements of the body. The eye he discusses briefly (p. 44f)). The interesting perceptual activity for Gregory, however, is in the brain.