1. Perception Chapter 6
Mr. McElhaney

2. “Seeing” Gregory explains vision: Pay attention to the following:
Gestalt, Foreground, Background, Silhouette
How does the eye select, filter and become conscious or make sense of visual world?
How does the perceptual system work?
What is the role of experience in perception?
What are illusions?

3. Questions to be answered
What is the role of experience in perception?
What is the role of culture ?
How does the mind make meaning of the stimuli from the environment?

4. Perception
Defined: The process by which the brain organizes and interprets sensory input.
is the process through which people actively use knowledge and understanding of the world to interpret sensations as meaningful experiences.
Making sense of visual stimuli
How we assemble sensations into meaningful patterns (sensation and perception are blended)
Perception is empirical= experiential

5. Perceptual Set/Context
Expectations are created by experience
“A set of mental tendencies and assumptions that affects what we perceive”
Context
Creates expectancy
Experience influences perception

6. Feature Detectors Occipital Lobe Visual Cortex From retina
Cells respond to specific features
Edges
Lines
Angles Movement

7. Parallel Processing Doing many things at once’ Motion Form Depth Color
All Simultaneous

8. Perceptual System Automatically distinguishes - Laws or Principles:
Figure/ground stimuli into patterns
Groups Stimuli
Laws or Principles:
Proximity
Similarity
Continuity
Closure
Common Fate – (visual) objects moving in unison
Synchrony- (Multiple Senses) stimuli that occur at the same time appear to belong together
Common Region- location boundary
Connectedness

9. Constancies Perceptual Constancy Size Constancy Shape Constancy
Perception needs experience
Must be familiar with objects to use their size to judge distance
Size Constancy
Perceived size of object remains the same even though size on the retina changes
Shape Constancy
Shape of an object remains constant
Alcohol impairs
Brightness Constancy
Brightness of objects appear to be the same if surrounding objects are illuminated- light

10. Perceptual Organization
Contrasts help perception
Object and plain background
Figure Ground- perception is first
Reversible figure ground
Perception is reversed
Background is more visible
The change in perception
is known as Ambiguous Stimuli

11. Gestalt Principles
We have a tendency to complete shapes into whole units
Factors of Perception that bring order to perceptions:
Visual depictions can be designed to be perceptually efficient.

12. Factors of Perception Gestalt Principles: “The whole is greater than its parts.”
Nearness- items near are grouped together items will be seen in groups
Similarity- perceived size/shape color form tend to be grouped together
Continuation- continuity- tend toward simplicity- it’s easier to visualize wavy line than complex rows
Closures- tendency to complete a figure so that it has an overall form
Common region- stimuli found in a common region or area seen as a group
Used in everyday patterns

14. Camouflage Breaks up foreground organization images
also known as cryptic coloration or concealing coloration, allows an otherwise visible organism or object to remain indiscernible from the surrounding environment.
© E.R. Degginger/Animals Animals

15. Perceptual Hypothesis
We find meaning and organize visual perceptions from a distance
We make judgments (hypotheses)
When we get closer the hypothesis is proved or disproved
We expect and understand based on experience we have preexisting ideas

16. Necker’s Cube Ambiguous stimuli Brain interprets patterns
Patterns that allow more than one interpretation
Brain interprets patterns
We actively construct meaningful perceptions/ not passive
Problem- Conflicting information prevents stable perception

17. Depth Perception Ability to perceive 3 dimensional space
Nativist= inborn ability Or
Empiricists = experience based
Depth perception is both

18. Visual Cliff The concept of testing depth perception in babies
Can babies identify Depth Cues?
Features of the environment and messages from the body that supply information about distance/depth

19. Study found that Infants have some innate depth perception.
Implications are that humans have both – innate and experiential abilities

20. Why do infants and babies fall off beds and things?
Depth perception and motor skills have not integrated yet

21. Depth Perception Perception of distance Stimulus Cues
Partly a physical structure of the Visual System

22. Depth Perception: Muscular Cues
Monocular or Binocular
Sensations from muscles attached to each lens flow back to the brain
Accommodation- (using muscles) bending of lens to focus on nearby object
Convergence= Distant vision = parallel within 50’ eyes converge
Controlled by muscles feed info to the brain helps judge distance

23. Convergence

24. Muscular Cue: Stereoscopic Vision=2 eyes
Focusing of image by two eyes = 3 dimensional sight
Retinal Disparity (Binocular cue)= two eyes, see the world differently
“Discrepancy in images that reaches right and left eye” (3 D movies pg 221)
Produces Depth
One eyed people can learn to perceive depth

27. Random Dot Stereogram-
Patterns of dots that produce an illusion of depth
Shows the brain is very sensitve to any mismatch

29. Pictorial Cues for Depth
Linear Perspective
Relative size
Height in picture plane
Light and shadow
Texture gradient
Overlap
Aerial perspective
Relative Motion

30. Fig. 6. 14 (a) Linear perspective. (b) Relative size
Fig (a) Linear perspective. (b) Relative size. (c) Light and shadow. (d) Overlap. (e) Texture gradients. Drawings in the top row show fairly “pure” examples of each of the pictorial depth cues. In the bottom row, the pictorial depth cues are used to assemble a more realistic scene.

31. The Moon Illusion Apparent distance Hypothesis:
Perceiving the moon as larger when it is low in the sky;
Problem: the moon is closer when the directly overhead
The brain thinks the low moon is larger because of Depth Cues
Horizon makes moon larger and closer
Apparent distance Hypothesis:
Existence of depth cues causes us to make distant objects seem closer.

32. Perceptual Learning
Refers to experiences that cause changes in the brain that alter how we process info
We learn to focus on one part of stimuli
We learn to tell the difference between stimuli

33. Perceptual Habits Through Experience We establish habits of perception
Patterns of organization and attention
Perceptual Features- are learned and the brain becomes sensitive to:
Lines, shapes, edges, spots, and colors

34. Ames Room- appears square, distorts proportions= Both Perceptual Habits and Perceptual Learning

35. Perceptual Habits continued
Other Race Effect
Inverted vision= human brain can adapt
Through active movement
People need to be active to adapt

36. Examples of Illusions

37. Illusions: Size Distance Variance
The size of an object’s image is precisely related to its distance from the eye
Two objects make images the same size

38. Perception cannot occur without attention
Motives for one stimulus will make perception for that stimulus more sensitive
Selective Attention: we give some messages priority.
Divide Attention: Causes us to divide attention among tasks that require more or less effort

39. Types of stimuli that impact attention
Intense stimuli commands attention
(brighter, louder, larger- Advertising psych)
Repetitious Stimuli- grabs attention
Contrast or changing stimuli gets attention

40. Other Factors to Attention
Inattentional Blindness Click first
The occurrence where when focused on a specific item we miss other information and items
Habituation= boredom, we respond less to unchanging stimuli <to not be stimulated>
Connected to Adaptation- decrease the actual number of sensory messages sent to brain

41. Biological Receptivity
Orientation Response: prepares us to receive information
Pupils enlarge
Brain patterns shift
Breathing stops
Blood flow to the head increases
Physical turn toward stimulus
“Double Take”

42. Perceptual Expectancies
Expecting stimuli in a certain manner
“Past experiences, motives, context”
“Prepares you to perceive in certain ways.”
“We see what we expect to see.”
Can be created by suggestion

43. Perceptual Expectancies
Bottom Up Processing- Feature analysis of info with sensory units build upward to a complete perception
A puzzle in pieces
Feature Analysis (Form, Color, Motion, lines, shapes, colors)
Analysis of info with sensory units
Build upwards to a complete picture

44. Top Down-Bottom Up Processing-
A complete picture (a known puzzle) taking the whole and analyzing it into parts
pre-existing knowledge used- to rapidly organize features (small units) to a whole Preexisting knowledge used to organize feature s to a whole
Gestalt
Influenced by expectancy and motivation and experience
Schemas- based on past experience can create a perceptual set
(Perceptual Set = the readiness to perceive stimuli in certain ways.)
Bottom Up = Stimulus Driven
Relying on specific details information from sensory receptors that are assembled into a whole.
Stimulus characteristics:
Sudden Changes in light or color,
Movement
Appearance of Unusual shapes
Knowledge and beliefs create expectations- that give meaning to the features. Interpretations that are suggested can be recognized

45. Perceptual Categories
Experiences are sorted into categories
Labels impact the way we perceive others-
Classes
Types
Groups

46. Eyewitness Testimony Is often incorrect
When a person is surprised, threatened, or under stress are especially prone to distortion

47. Maslow and Perception
Found some people perceive themselves and others with great accuracy.
Characteristics:
Lack Self Consciousness
Not critical
Not evaluating
Problem of Habituation- boredom, responding less to stimuli
Need to Dishabituate- reverse habituation = pay attention
Examples of:
Mother and infant
Christmas
Two people in love

48. How to Improve Perception
Remember perceptions are reconstructions of reality
Break perceptual habits and interrupt habituation
Shift adaptation levels and broaden frames of reference by seeking out of the ordinary experiences
Beware of perceptual sets
Be aware of the ways in which motives and emotions influence perceptions
Make a habit of engaging in reality testing.
Pay attention