Visual Organization and Interpretation

1. Visual Organization and Interpretation Module 19

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

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

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

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

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

7. 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

8. 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.

9. 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.

11. 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.

12. 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.

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

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

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

16. 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)