Visual Organization and Interpretation Module 19

Visual Organization Gestalt – an organized whole. Gestalt psychologists emphasized our tendency to integrate pieces of information into meaningful wholes.

Form Perception Figure ground – the organization of the visual field into objects(the figures) that stand out from their surroundings(the ground)

Form perception - grouping Proximity – our tendency to group things that are near each other.

Form perception - grouping Continuity – our tendency to see things as a smooth continuous line

Form Perception - grouping Closure – the tendency to perceive a complete or whole figure even when there are gaps in what your senses tell you.

Depth Perception Depth perception – the ability to see objects in three dimensions although the images that strike the retina are two-dimensional; allows us to judge distance Visual Cliff – a laboratory device for testing depth perception in infants and young animals Binocular Cues – depth cues that depend on the use of two eyes Retinal disparity – by comparing images from the retinas in the two eyes, the brain computes distance – the greater the disparity (difference) between the two images, the closer the object Convergence – the extent to which the eyes converge inward when looking at an object

Monocular Cues – depth cues available to either eye alone. Interposition: if one object partially blocks our view of another, we perceive it as closer. Linear perspective: parallel lines appear to meet in the distance. Light and shadow: shading produces a sense of depth consistent with our assumption that light comes from above.

Relative height: we perceive objects that are higher in our field of vision to be farther away than those that are lower. Relative size: If two objects are roughly the same size, the object that looks the largest will be judged as being the closest to the observer. Relative Motion: as we move, objects that are actually stable may appear to move.

Motion Perception As objects move, we assume that shrinking objects are retreating and enlarging objects are approaching. To see movement humans need to see an object change its position relative to other objects. A rapid series of slightly varying images – stroboscopic movement (flip books) Phi phenomenon – an illusion of movement created when two or more adjacent lights blink on and off in quick succession.

Perceptual Constancies - Perceptual constancy – perceiving object as unchanging even as illumination and retinal images change. Color Constancy: we perceive an object as having a constant lightness even while its illumination varies.

Perceptual Constancies Brightness/lightness constancy – perceiving objects as having constant brightness even when its illumination varies

Perceptual Constancies Shape constancy - we perceive the form of familiar objects as constant even while our retinal images of them change.

Perceptual Constancies Size Constancy – we perceive objects as having a constant size, even while our distance from them varies.

Visual Interpretation Immanuel Kant – organizing our sensory experiences is inborn John Locke – we learn to perceive the world through experience Experience and visual perception: Studied people blind at birth who later regained sight: After surgery – could distinguish figure-ground and sense color but could not visually recognize objects that were familiar by touch Suggests a critical period for normal sensory and perceptual development Perceptual adaptation – in vision, the ability to adjust to an artificially displaced or even inverted visual field https://www.youtube.com/watch?v=n46umYA_4dM (crash course)