Ibn Sahl 984 Laws of refraction

Ibn al-Haytham (Alhazen) Book of optics 1011-21. Ray theories of light Human Visual System

Visual Attention & Visual Perception Sight and Seeing Cognition and Eye Movement (saccade) Top-down cognition Memory Priming Knowledge Bottom-up Stimulus feature processing pattern recognition

Bracketed Perception vs. Normal Perception A bounded visual space, oval, approximately 180° laterally, 150° vertically Clarity of focus at only one point with a gradient of increasing vagueness toward the margin Parallel lines appear to converge If the head is moved, the shapes of objects appear to be deformed The visual space appears to lack depth A world of patterns and sensation, of surfaces, edges and gradients  Unbounded visual space Clarity of focus throughout Parallel lines extend without converging If the head is moved, shapes remain constant Visual space is never wholly depthless A world of familiar objects and meaning