1. Chapter 5
PERCEPTION

2. Sensations vs. Perceptions
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

3. Sensations vs. Perceptions (continued)
Parts of the Brain transform electrical signals into basic sensations
Sensations 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

4. Sensations vs. Perceptions (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

5. Enduring Issues in Perception
Role of Learning
Newborns’ senses are all functional and some degree of perceptual ability is probably innate

6. Enduring Issues in Perception (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)

7. Enduring Issues in Perception (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”

8. Enduring Issues in Perception (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.

9. Functions 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)

10. Functions of Perception: Depth Perception (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

11. Functions of Perception: Depth Perception (continued)
Monocular Depth Cues
Depend upon the signals sent from one eye
Determined by how objects are arranged in the environment

12. Functions of Perception: Depth Perception (continued)
Motion Parallax
Relative Size
Constancy
Linear Perspective
Texture Gradient
Aerial Perspective
Occlusion (Interposition)

13. Functions of Perception (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

14. Functions of Perception (continued)
Auditory Localization
Differences in how and when a sound reaches the two ears enable the brain to compute the location of its source

15. Functions of Perception (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

16. Functions of Perception (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)

17. Functions of Perception (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

18. Functions of Perception (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

19. Functions of Perception (continued)
Gestalt View (continued)
Grouping
Similarity
Proximity
Continuity
Simplicity
Closure

20. Subliminal 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

21. Cultural Diversity: Changing Perceptions
Besides affecting social and personal values, cultural influences can also affect our perception of color depth, constancy, and motion

22. 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

23. 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)

24. Application: Creating Perceptions
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

25. Application: Creating 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

26. Life-Span Changes in Perception
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

27. Life-Span Changes in Perception
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