1. (with Sensation 6-8% of AP Exam)
Perception
(with Sensation 6-8% of AP Exam)

2. Perception
“Top-down” processing: a progression from the whole to the elements
The process of selecting, organizing and interpreting our sensations.
In many situations your knowledge or expectations (schemas) will influence perception.

5. Do you see the arrow?

7. Attention and Behavior
Selective Attention and Selective Inattention

8. Selective Attention
Selective Attention – focusing conscious awareness on a particular stimulus to the exclusion of others.
Ex. Blocking out the talking of the student next to you so that you can complete your assignment.
Ex. Being so “caught up” in the TV show you are watching that you didn’t notice someone enter the room.
Ex. Busy texting while driving that you fail to notice the semi-truck headed right for your windshield.

10. Selective Attention
Cocktail Party phenomenon – the ability to attend to only one voice among many

11. Selective Attention
Pop-out phenomenon – when stimuli are so powerful or distinct that we automatically notice the change

12. Selective Inattention
Inattentional blindness – failing to see visible object when our attention is directed elsewhere

13. Selective Inattention
Change blindness – failing to notice changes in the environment

14. Gestalt Principles
Looking at the Whole Picture

15. Perceptual Organization
Gestalt psychologists emphasized our tendency to integrate pieces of information into meaningful wholes.
How we organize our sensations into perceptions.
Figure-ground: perceiving an object (called the figure) as distinct from its surroundings (called the ground)
Faces or Vase?

19. Proximity – We group nearby figures together.
Gestalt Principles
Proximity – We group nearby figures together.

20. Similarity – We group together figures that are similar to each other.
Gestalt Principles
Similarity – We group together figures that are similar to each other.

22. Gestalt Principles
Continuity – We perceive smooth, continuous patterns rather than discontinuous ones.

23. Gestalt Principles
Connectedness – Because they are uniform and linked we perceive the two dots and the line between them as a single unit.

24. Gestalt Principles
Common Fate: we tend to group similar objects together that share a common motion or destination

25. Closure – We fill in gaps to create a complete, whole object.
Gestalt Principles
Closure – We fill in gaps to create a complete, whole object.

28. Perceiving Depth and Distance

29. Depth Perception
Depth perception – the ability to see objects in three dimensions although the images that strike the retina are two-dimensional
Allows us to judge distance.
Visual cliff – (at right) laboratory device for testing depth perception in infants and young animals

30. Binocular cues – Depth cues that depend on the use of two eyes.

31. Depth Perception – Binocular Cues
Retinal disparity – objects project images to slightly different locations on the right and left retinas
Therefore the right and left eyes see slightly different views of the same object
The larger the disparity between the two images, the closer the object

32. Depth Perception – Binocular Cues
Convergence – the extent to which the eyes converge inward when looking at an object

33. Monocular Cues – depth cues available to either eye alone

37. Depth Perception – Monocular Cues
Relative Size – if we assume that two objects are similar in size, we perceive the one that casts the smaller retinal image as farther away

38. Depth Perception – Monocular Cues
Interposition – if one object partially blocks our view of another, we perceive it as closer.

40. Depth Perception – Monocular Cues
Relative clarity – because light from distant objects passes through more atmosphere, we perceive hazy objects as further away than sharp, clear objects.

41. Depth Perception – Monocular Cues
Texture gradient – a gradual change from a coarse, distinct texture to a fine, indistinct texture signals increasing distance

42. Depth Perception – Monocular Cues
Relative height – we perceive objects higher in our field of vision as farther away; lower in the field as closer

43. Depth Perception – Monocular Cues
Linear perspective – parallel lines appear to converge with distance

44. Depth Perception – Monocular Cues
Light and shadow – nearby objects reflect more light to our eyes; given two identical objects, the dimmer ones seems farther away

45. Motion Perception
Relative motion (motion parallax)– as we move, objects that are actually stable may appear to move
Objects closer than the fixation point appear to move backward and faster.
Objects beyond the fixation point appear to move with you and slower.

47. Motion Perception
We tend to perceive that shrinking objects are retreating and enlarging objects are approaching.
We tend to perceive that larger objects more move slowly than smaller objects.

48. Motion Perception
Stroboscopic movement – rapid movement in a rapid series of slightly varying images (i.e. motion pictures)
Phi phenomenon – an illusion of movement created when two or more adjacent lights blink on and off in quick succession

49. The Influence of Experience and Culture
How do experience and culture influence perception?

50. Perceptual Set
Our experiences, assumptions and expectations may give us a perceptual set, or mental predisposition, that greatly influences what we see.

51. Expectation and Perceptual Set

52. 'The Cat Sat on the Map and Licked its Whiskers.'

55. Context Effects
Similar stimuli can evoke different perceptions in different contexts (i.e. time and space)
These different perceptions are called context effects.
Is the box in the far left frame lying on the floor or hanging from the ceiling?
What about the one of the far right?
In each case, the context defined by the inquisitive rabbits guides our perception.

57. Cultural Perceptions: What’s for Dinner?
A study found that subjects from a rural African tribe who had little exposure to pictures and photos, frequently misinterpreted the depth cues in the picture.

58. The Muller-Lyer Illusion
Both parallel lines are equal lengths.

59. The Muller-Lyer Illusion

60. Cultural Influences in Susceptibility
Studies have discovered that people in non-Western cultures are less susceptible to the Muller-Lyer Illusion than Western samples.
The most plausible explanation is that in the West we live in a “carpentered world” dominated by straight lines, right angles and rectangular rooms.
Thus our experience in the Western world readily prepares us to view the Muller-Lyer Illusion as inside and outside corners of buildings.
In contrast, people in some non-Western cultures who live in less “carpentered worlds” are less prone to see the Muller-Lyer as building corners.

62. Vulnerability to Illusions
The Role of Top-Down Processing

63. Perceptual Constancy
Perceptual constancy – perceiving objects as unchanging (having consistent color, lightness, shape and size) even as illumination, angle, distance and retinal images change
Shape Constancy
Size Constancy

64. Light Constancy

65. Size-Distance Relationship

66. Miscellaneous Illusions

67. Moon Illusion
Naturally occurring optical illusion in which the moon appears larger on the horizon than it does higher up in the sky.

69. Aoccdrnig to a rscheearch at Cmabrigde Uinervtisy, it deosn’t mttaer in waht oredr the ltteers in a wrod are, the olny iprmoetnt tihng is taht the frist and lsat ltteer be at the rghit pclae. The rset can be a total mses and you can sitll raed it wouthit a porbelm. Tihs is bcuseae the huamn mnid deos not raed ervey lteter by istlef, but the wrod as a wlohe.

71. Parapsychology

72. Parapsychology Parapsychology: the study of paranormal phenomena
Extrasensory Perception (ESP): claim that perception can occur apart from sensory input. Includes:
1. telepathy: communication by perceiving another’s thoughts
2. clairvoyance: perceiving remote events (those happening elsewhere)
3. precognition: perceiving future events before they happen
Closely linked to ESP is telekinesis: the ability to move objects with the mind.