PERCEPTUAL ORGANIZATION

 When we are given a cluster of sensations, we organize them into a “gestalt” or a “whole”  “The whole is greater than the sum of the parts.”  We take in sensory information and infer a perception that makes sense to us based on our past experiences.

What is a Figure/Ground Relationship?  Discriminate the focus of stimulus from the background. One stimulus can trigger more than one perception.

How Do We Organize Stimuli Into a Meaningful Form?  Our mind has “Rules” for Grouping  1. Proximity

 2. Similarity

 3. Continuity

 4. Connectedness

 5. Closure

Examples of Grouping

DEPTH PERCEPTION  Seeing things in 3 dimensions—but we only have a 2-dimensional retina  Both an innate (born with it) and a learned skill  Utilizes both “binocular” clues and “monocular clues”

Visual Cliff Experiment

Binocular Clues  Retinal Disparity  Our eyes are about 2 ½ inches apart  Provides an important clue to the relative distance between 2 objects  Retinal disparity is greatest directly in front of your face

Let’s Make Finger Sausages!

3D Movies Increase Retinal Disparity!

It’s More Difficult to Judge Distant Objects  Much less retinal disparity  We depend on monocular depth clues  1. Relative height  2. Relative size  3. Linear perspective  4. Light and shadow  5. Interposition  6. Relative Motion

We Depend on Monocular Clues 1. Relative height: We perceive object higher in our visual field as being further away.

We Depend on Monocular Clues But…

We Depend on Monocular Clues  2. Relative Size: If we assume that 2 objects are roughly the same size, we perceive the one that “looks” smaller (casts a smaller retinal image) to be further away

We Depend on Monocular Clues  3. Linear Perspective: The more parallel lines converge (come together), the greater their perceived distance.

We Depend on Monocular Clues  4. Light and Shadow: Nearby objects reflect more light to our eyes. If 2 objects identical in shape and size, the dimmer one appears further away. Also, our brain “assumes” that light comes from above.

We Depend on Monocular Clues  5. Interposition: If one object blocks the view of another, we perceiving the “blocking” object as being closer.

We Depend on Monocular Clues  6. Relative Motion: If we ourselves move, objects that are actually stable may appear to move.

Let’s Review Depth Perception Reviewing Depth Perception

MOTION PERCEPTION  Shrinking objects are retreating  Enlarging objects are approaching  Large objects appear to move slower than smaller objects moving at the same speed Tennis Shoe and Batteries

Motion Perception  Stroboscopic Movement

Motion Perception  Phi Phenomenon Phi Phenomenon

PERCEPTUAL CONSTANCY  How we recognize objects without being deceived by changes in their:  Shape  Size  Brightness  Color

Shape Constancy

 But we can be fooled

Size Constancy

 But we can be fooled…

Color & Light Constancy

Light Constancy  But we can be fooled… Perceptual Constancy

PERCEPTUAL INTERPRETATION  Life experience has a huge impact

Perceptual Adaptation  Can we change how we perceive?

Perceptual Set  Emotions, expectation, and context ALL influence our perceptions

The Brain is a Great ‘Face Detector’

It’s All About Context

Even Culture Influences Context