1. Chapter 8- Sensation and Perception

3. Perceptual Illusions
Illusions provide good examples in understanding how perception is organized. Studying faulty perception is as important as studying other perceptual phenomena.
OBJECTIVE 2| Explain how illusions help us understand some of the ways we organize stimuli into meaningful perceptions.
Line AB is longer than line BC.

4. Perception
The brain receives information from the senses and unconsciously organizes into meaningful experiences
Makes whole structures out of bits and pieces of info in the environment
Gestalt- this meaningful whole (German for pattern). The study of how parts are organized into whole perceptions

5. Gestalt Grouping Principles
group nearby figures together
proximity
group figures that are similar
similarity
perceive continuous patterns
continuity
fill in gaps
closure
spots, lines and areas are seen as unit when connected
connectedness 5

6. Gestalt Grouping Principle 1
How are perceptions constructed?
Proximity:
occurs when elements are placed close together. They tend to be perceived as a group.

7. Gestalt Grouping Principle 2
How are perceptions constructed?
Similarity:
occurs when objects look similar to one another. People often perceive them as a group or pattern.

8. Gestalt Grouping Principle 3
How are perceptions constructed?
Continuity:
occurs when the eye is compelled to move through one object and continue to another object.

10. Gestalt Grouping Principle 4
How are perceptions constructed?
Closure:
occurs when an object is incomplete or a space is not completely enclosed. If enough of the shape is indicated, people perceive the whole by filling in the missing information

12. Figure Ground Perception:
The ability to discriminate properly between a figure and its background

13. Perceptual Inference:
Filling in the gaps in what our senses tell us
Assuming the sound of barking is a dog
Assuming a chair will hold us even in a dark theater
Depends on experience

14. Learning to Perceive In large part, something we learn to do
Infants under one month will smile at a nodding image the size of a human face
At about 20 weeks, a blank oval will not, but a mask will
At 30 weeks, will smile more readily at a familiar face
Will not be able to recognize different people until 7 or 8 months
Learning to perceive is influenced by environment interaction, needs, beliefs, and experiences

15. Subliminal Perception
Brief auditory or visual messages present below the absolute threshold so that there is a less than 50% chance that they will be perceived
False claim that the words “Eat popcorn” and “Drink Coke” had flashed briefly on a movie screen once every 4 seconds for 1/3000 of a second and that sales had risen
Hysterical reaction- Congress called for FCC, admitted data was false. But still banned in 1974, regardless of efficacy
Even if it is possible for people to perceive info at low levels of intensity, no clear evidence that they influence people. But many believe it is a powerful advertising tool

16. Depth Perception:
The ability to recognize distances and three dimensionality
Present in infancy
Testing infants 6-14 months: most have depth perception

17. Binocular Fusion
The process of combining the images received from the two eyes into a single, fused image
Retinal disparity- the difference between the images stimulating each eye
Essential to depth perception- a large retinal disparity means an object is nearby

18. Visual Cliff
The Visual Cliff is a test given to infants to see if they have developed depth perception.
Then, a piece of glass or other clear material is placed on top of the platform and extends well off of the platform, creating a sort of bridge.
An infant is then placed on the platform, and the infant's mother stands on the other side of the clear bridge.
The mother calls for the child who, if it crawls off the platform and onto the clear bridge, it does not yet have depth perception.
If it stops when it gets to the edge of the platform, looks down, and either is reluctant to cross or refuses to cross, then the child has depth perception.

19. Monocular Depth Cues: Perceive distance and depth with a single eye
Relative size: bigger = nearer
Relative clarity: closer objects appear clearer than distant objects
Interposition: closer objects block distant objects

20. Monocular Depth Clues:
Motion Parallax- the apparent movement of objects when you move from side to side or walk around; Near objects seem to move more
Linear Perspective- parallel lines will converge in the distance
Relative motion- objects nearby are moving in the opposite direction objects far away are moving in the same direction

21. Binocular Depth Cues:
Convergence- turning eyes inward to look at near objects
Retinal Disparity- larger the difference = closer

22. Constancy:
The tendency to perceive certain objects in the same way regardless of changing angle, distance, or lighting

23. Illusions
Perceptions that misrepresent physical stimuli; cues are distorted
Converging lines = distance

26. Extrasensory Perception
An ability to gain information by some other means other than the ordinary senses
Clairvoyance- perceiving objects or information
Telepathy- reading someone's mind or transferring thoughts
Psychokinesis- moving objects through purely mental effort
Precognition- ability to foretell events

27. Extrasensory Perception
James Randi has campaigned against people who say they have ESP
Many are convinced because of an intense personal experience that cannot be scientifically validated
Successes and failures must be taken into account
Findings are unstable and contradictory