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Unit 4: Sensation & Perception. Module 16: Perceptual Organization. Perceptual Illusions. Illusions reveal the ways we normally organize and interpret our sensations . Visual Capture – the tendency for vision to dominate the other senses.
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Unit 4: Sensation & Perception Module 16: Perceptual Organization
Perceptual Illusions • Illusions reveal the ways we normally organize and interpret our sensations. • Visual Capture – the tendency for vision to dominate the other senses. • When vision competes with other senses, it usually wins.
Ames Room • Invented by ophthalmologist Adelbert Ames, Jr. in 1934. • The Ames room was designed to manipulate distance cues to make two same-sized girls appear very different in size.
Organizational Principles • Gestalt – organizing pieces into a meaningful “whole”. • Gestalt psychologists emphasized our tendency to integrate pieces of information into meaningful wholes. • We take information and infer perceptions in ways that make sense to us.
Figure and Ground Perception • Figure – Object • Ground – Surroundings • Figure-Ground – the organization of the visual field into objects that stand out from their surroundings. Goblet or two faces? Stepping man, or arrows?
Grouping • Proximity – Group nearby figures together. We don’t see 6 separate lines, but 3 sets of two lines. • Similarity – We group together figures that are similar to each other. We see triangle and circles as vertical columns, not horizontal shapes.
Grouping • Continuity – We see smooth, continuous patterns. • Two lines or semicircles? • Connectedness – We see the two dots and the line as a single unit. • Closure – We fill in the gaps to create a complete, whole object. Triangles?
Depth Perception • Depth Perception – Seeing two dimensional objects as three dimensional. • Allows us to estimate distance. This is a painting on the sidewalk.
Depth Perception • Visual Cliff – test of depth perception in babies. • Babies develop this ability at crawling age.
Binocular Cues • Binocular Cues – depth cues that depend on the use of two eyes. • Retinal disparity – the slightly different view the two eyes have of the same object because the eyes are a few centimeters apart. • The degree of retinal disparity decreases with distance. • With both eyes open, your brain fuses the two images, resulting in perception of depth.
Binocular Cues • Convergence – the inward turning of the eyes that occurs when you look at an object that is close to you. • The closer the object, the more convergence. • Look at your nose. Your eyes converge inward.
Monocular Cues • Monocular Cues – depth cues using either eye alone. • Relative Size – The closer of two same size objects casts a larger image on your retina than the farther one. Bigger canoe is closer.
Monocular Cues • Interposition – one object partially blocks our view of another, we see it as closer. Triangle is closer because it blocks the circle and square.
Monocular Cues • Relative Clarity – closer objects appear sharper than more distant, hazy objects. Hazy, cloudy forest is farther away than clear, sharp trees.
Monocular Cues • Texture Gradient – closer objects have a coarser, more distant texture than far away objects that appear more densely packed or smooth. Circles look closer, while densely packed areas seem farther away.
Monocular Cues • Relative Height – The lowest objects in our field of vision seem the closest. Images higher in the picture seem farther away. Night? Ground Figure
Monocular Cues • Relative Motion (Motion Parallax) – As we move, objects that are actually stable appear to move. Nearby objects pass quickly while far away objects appear stationary.
Monocular Cues • Linear Perspective – Parallel lines seem to converge in the distance. The tracks seem to meet in the distance. 1 point perspective
Monocular Cues • Light and Shadow (Relative Brightness) – Closer of two identical objects reflects more light to your eyes. Seems closer because it reflects more light.
Motion Perception • Phi Phenomenon – the illusion of motion created by presenting visual stimuli in rapid succession. • Flipbook video!
Shape and Size Constancies • Shape Constancy – an object appears to maintain its normal shape regardless of the angle from which it is viewed.
Shape and Size Constancies • Size Constancy – an object appears to stay the same size despite changes in the size of the image as it moves farther away or closer.
Shape and Size Constancies • Size-Distance Relationship – Farther objects seems larger.
Lightness Constancy • Brightness Constancy – an object maintains a particular level of brightness regardless of the amount of light reflected from it. • However, when the context changes, the perceived brightness or color can also change. Remember A & B are the same color, but we perceive B as lighter because of the surrounding context.