Review Sheet Perceprion

What is the relationship between sensation and perception?

Percept is what we perceive / a product of peception

Perceptual Processing

Feature Detectors - specialized cells dedicated to the detection of specific stimulus features

Binding Problem - how does our brain combine all these sensory operations into a single percept?

1. Top-Down Processing – conceptually driven processing - use the past and present and we perceive by filling in gaps in what we sense

Schemata

Perceptual set

Perceptual Constancies: color, shape, and size

2. Bottom-up Processing, also called stimulus - driven or feature analysis – we use only the features of the object itself to build a complete perception

Perceptual Ambiguity and Distortion:

What do illusions teach us about perception?

Herman Grid

Tops Down Processing

Mueller Lyer Figure

Necker Cube

Phi Phenomenon click on PICTURE - apparent movement based on sequential presentation of stationary images - fireworks vreate that pattern as well

Classical Explanations for Perception

GESTALT RULES- How we organize stimulation into meaningful patterns based on the way our brain is structured (innate)

Proximity

Similarity

Continuity

Closure

Figure Ground

CONSTANCY- Tendency to perceive objects as stable and unchanging despite changes in sensory stimulation

• Size constancy - Perception of an object as the same size regardless of the distance from which it is viewed
• Shape constancy - Tendency to see an object as the same shape no matter what angle it is viewed from
• Brightness constancy - Perception of brightness as the same, even though the amount of light reaching the retina changes

LEARNING BASED PERCEPTION

HELMHOLTZ - We use prior learning to interpret new sensory information / inferences based on what we know

Context

Expectations

Perceptual Set

Cultural Influences

DEPTH CUES

Visual cliff experiment-Gibson and Walk Experiment

Monocular cues - Visual cues requiring the use of one eye

Interposition - Monocular distance cue in which one object, by partly blocking a second object, is perceived as being closer.

Linear perspective - Monocular cue to distance and depth based on the fact that two parallel lines seem to come together at the horizon

Relative size-Monocular cue in which closer objects seem larger than distant objects

Texture gradient-Course objects appear closer than smooth objects

Shadowing-lighter objects appear closer than darker objects

Binocular cues - Visual cues requiring the use of both eyes

Retinal disparity - Binocular distance cue based on the difference between the images

Convergence- cast on the two retinas when both eyes are focused on the same object

Stereoscopic vision - Combination of two retinal images to give a three-dimensional perceptual experience.