How Do We See a Changing World?

This chapter begins an analysis of how we see changing visual images and scenes. It explains why moving objects do not create unduly persistent trails, or streaks, of persistent visual images that could interfere with our ability to see what is there after they pass by. It does so by showing how the circuits already described for static visual form perception automatically reset themselves in response to changing visual cues, and thereby prevent undue persistence, when they are augmented with habituative transmitter gates, or MTM traces. The MTM traces gate specific connections among the hypercomplex cells that control completion of static boundaries. These MTM-gated circuits embody gated dipoles whose rebound properties autonomically reset boundaries at appropriate times in response to changing visual inputs. A tradeoff between boundary resonance and reset is clarified by this analysis. This kind of resonance and reset cycle shares many properties with the resonance and reset cycle that controls the learning of recognition categories in Adaptive Resonance Theory. The MTM-gated circuits quantitatively explain the main properties of visual persistence that do occur, including persistence of real and illusory contours, persistence after offset of oriented adapting stimuli, and persistence due to spatial competition. Psychophysical data about afterimages and residual traces are also explained by the same mechanisms.