Chapter 5Chapter 5

PERCEPTIONPERCEPTION

Sensations vs. PerceptionsSensations vs. Perceptions

Perception Our interpretations of the real world

How do Sensations Become Perceptions A perception begins with some stimulus

which activates sense receptors Once activated, a sense organ

transforms energy into electrical signals or impulses that travel to the brain

Sensations vs. Perceptions Sensations vs. Perceptions (continued)(continued)

Parts of the Brain transform electrical signals into basic sensationsSensations are your first experiences of outside stimuli They consist of meaningless bits of sensory

information

Each of us has a unique set of experiences that may automatically add meanings, feelings, or memories to our perceptions

Sensations vs. Perceptions Sensations vs. Perceptions (continued)(continued)

The brain automatically assembles many thousands of individual sensations into a meaningful pattern or image which is called perception Personalized interpretations rather

than true copies of things in the real world

Enduring Issues in Enduring Issues in PerceptionPerception

Role of Learning Newborns’ senses are all functional

and some degree of perceptual ability is probably innate

Enduring Issues in Perception Enduring Issues in Perception (con’t)(con’t)

Parts vs. the Whole Feature Analysis

The theory that we perceive a form on the basis of a relatively small collection of features, which can be combined, rotated and expanded (Structuralism)

Enduring Issues in Perception Enduring Issues in Perception (con’t)(con’t)

Gestalt School Psychologists who

believe that a meaningful overall pattern (Gestalt) is perceived before its parts are recognized

“The whole is more than the sum of its parts”

Enduring Issues in Perception Enduring Issues in Perception (con’t)(con’t)

Perceptual Illusions Used to determine how people process

perceptual information

Bottom-Up vs. Top-Down Processing Bottom-Up: sensory receptors to brain Top-Down: perceiver’s expectations &

context play a role from the beginning Perceptual Sets:

learned expectations that are based on our personal social or cultural experiences. These expectations change or bias what we see.

Functions of PerceptionFunctions of Perception

Where is it? – Location Attention

Automatic – distinguishing object from background

Deliberate – allocation of attention Depth Perception

Ability to experience depth in visual perception (relative & absolute distances)

Functions of Perception:Functions of Perception: Depth Perception Depth Perception (continued)(continued)

Binocular Depth Cues – depend upon the movement of both eyes Convergence – based on signals sent

from the muscles that turn the eyes Binocular (Retinal) Disparity –

depends on the distance between the eyes Stereopsis 3-D Glasses

Functions of Perception:Functions of Perception: Depth Perception Depth Perception (continued)(continued)

Monocular Depth Cues Depend upon the signals sent from

one eye Determined by how objects are

arranged in the environment

Functions of Perception:Functions of Perception: Depth Perception Depth Perception (continued)(continued)

Motion ParallaxRelative SizeConstancyLinear PerspectiveTexture GradientAerial PerspectiveOcclusion (Interposition)

Functions of Perception Functions of Perception (continued)(continued)

Illusions of Depth Muller-Lyer, Ponzo, Ames Room, Vista

Paradox (pg. 146) If our perceptual cues are changed,

our otherwise reliable perceptual processes can be deceived

Functions of Perception Functions of Perception (continued)(continued)

Auditory Localization Differences in how and when a sound

reaches the two ears enable the brain to compute the location of its source

Functions of Perception Functions of Perception (continued)(continued)

Is it Moving? – Movement Motion Perception

We distinguish between changes in environment that are caused by movements in the environment and changes that are caused by our own movements

Functions of Perception Functions of Perception (continued)(continued)

Illusions of Motion Apparent Motion (Phi Phenomenon) Induced Motion (moon appears to

move through clouds) Motion Aftereffect (train stops and

objects outside appear to move backwards)

Functions of Perception Functions of Perception (continued)(continued)

What is It? – Form Feature Analysis

Involves the recognition of features (lines, intersections & corners) as well as location, orientation, contrast, and fuzziness.

Features are grouped into clusters

Functions of Perception Functions of Perception (continued)(continued)

Gestalt View (Principles) Figure-Ground Distinction

In organizing stimuli, we tend to automatically distinguish between a figure and a ground

The figure with more detail, stands out against the background, which has less detail

Functions of Perception Functions of Perception (continued)(continued)

Gestalt View (continued)Grouping Similarity Proximity Continuity Simplicity Closure

Subliminal PerceptionSubliminal Perception

Subliminal Messages Brief auditory or visual messages that are

presented below the absolute threshold, which means that there is a <50% chance that they will be perceived

Although subliminal messages may be ineffective in changing behavior, there is evidence that emotions may unknowingly or subliminally influence perception

Cultural Diversity: Cultural Diversity: Changing PerceptionsChanging Perceptions

Besides affecting social and personal values, cultural influences can also affect our perception of color depth, constancy, and motion

ESP: Extrasensory Perception

A group of psychic experiences that involve perceiving or sending information outside normal sensory processes or channels Includes 4 general abilities

Telepathy Precognition Clairvoyance Psychokinesis

ESP: Extrasensory Perception (con’t)

Most academic psychologists do not yet accept the existence of psychic powers or extrasensory perception, which are collectively called psi phenomena Trickery Questionable methodology (unreliable

scientific procedures)

Application: Creating Application: Creating PerceptionsPerceptions

Creating Reality Virtual Reality

A perceptual experience of being inside an object, moving through an environment, or carrying out some action – that is entirely simulated by a computer

Application: Creating Application: Creating Perceptions (continued)Perceptions (continued)

Creating Impressions Social psychologists have concluded

that facial features have a significant affect on our first impressions of people

First impressions are also influenced by racial stereotypes, both positive and negative, based on physical features such as skin and hair color

Life-Span Changes in Life-Span Changes in PerceptionPerception

Sensory World of Infant A newborn’s distance senses (sight &

hearing) are not as developed as the sense of touch, smell & taste

Sight is probably the least developed sense They have poor depth perception and are

unable to see the full color spectrum By the age of 7 months, babies’ vision &

hearing are acute

Life-Span Changes in Life-Span Changes in PerceptionPerception

The Aging Senses Sensory systems begin aging during

the 40s and may become severe by the 70s and 80s

Life in a noisy environment may contribute to hearing loss

Medication may reduce taste sensitivity