History of psychiatry. Disorders of sensations and perception.
Chapter 5 PERCEPTION. Sensations vs. Perceptions Perception Our interpretations of the real world...
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Transcript of Chapter 5 PERCEPTION. Sensations vs. Perceptions Perception Our interpretations of the real world...
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