How you perceive your surroundings Perception How you perceive your surroundings

What is Perception? (Again) Perception first involves finding and attending to a stimulus, then distinguishing the stimulus from everything else (the background) and identifying the stimulus. These steps occur so quickly and with so little effort that it takes careful study to understand how complicated it all is

Pay Attention! Attention: a process in which consciousness is focused on particular stimuli 1. Selective attention: ability to focus on one stimulus while excluding other stimuli that are present 2. Divided attention: ability to respond to more than one stimulus

Perceptual Abilities Perceptual organization: processes that group smaller units of the perceptual world into larger units Gestalt (German for “whole”): The whole experience is greater than the sum of the individual parts. Figure-ground perception: tendency to organize the visual field into objects (figures) that stand apart from surroundings (ground)

Gestalt Perception Gestalt principles of perceptual organization: Gestalt psychologists believed that the world is organized around best forms—some of which are defined geometrically, such as a circle, square. Perceptual systems tend to “gravitate” toward those forms so that the resultant perception may be biased toward a particular interpretation.

Gestalt Perception 1. Law of Pragnanz - Also called the law of simplicity b. Tendency to see things in the simplest form 2. Closure: filling in missing information from the perceptual array by closing in gaps 3. Laws of grouping a. Similarity: grouping things on the basis of how similar they are to one another b. Proximity: grouping things on the basis of how near they are to one another

Proximity

Similarity

Closure

More weird Gestalt stuff

Other Perceptual Abilities Perceptual constancy Shape constancy: Perceived shape of an object remains constant despite changes in the shape of the retinal image of that object. Size constancy: Perceived size of an object remains constant despite changes in the size of the retinal image of that object.

Depth Perception Depth perception: perceived by using a number of cues Binocular cues: depth cues provided by both eyes Binocular disparity: takes account of the disparate images of each retina; a depth cue resulting from slightly different images produced by the retina of the left eye and the retina of the right eye

Monocular cues: depth cues provided by one eye a. Motion parallax is the phenomenon where near objects are seen as moving more rapidly than far objects when the viewer’s head is moving. b. Texture gradient is when the texture of a surface receding in the distance changes in clarity, blurring at further distances. c. Linear perspective is produced by apparent converging of parallel lines in the distance

More Monocular Interposition: One item blocks the view of items in back of it. Relative height: Objects higher in the perceptual field are farther away. Light and shadow: Lighter objects appear closer.

Pattern Perception Also called form perception Refers to recognition and identification of faces, words, shapes, melodies, and so on Begins with specific features, such as lines, and builds a perception that provides a more complex form. Feature-analysis theory: Patterns are identified by a stepwise perceptual and decisional analysis of their distinctive features. A template theory describes pattern recognition. Patterns are identified by comparing whole patterns to mental blueprints (templates) stored in memory until an exact match is found.

Illusions Perceptual illusions occur when sensory stimuli are misinterpreted; demonstrate how we typically interpret sensations. Perceptual illusions include the Müller-Lyer illusion, the Ames room, other illusions based on Gestalt principles (e.g., closure), and other perceptual sets mentioned above. Perceptual illusions demonstrate how easy it is to misinterpret sensory input. However, illusions also reveal the strategies we use to interpret sensations correctly