1. Sensation and Perception
Modules 17, 18 , 19

2. What we’ll sense and perceive… in this chapter:
especially vision and hearing
smell, taste, touch, pain, and awareness of body position
How do the sense organs and nervous system handle incoming sensory information?
How does the brain turn sensory information into perceptions?
Why is our style of creating perceptions better at perceiving the real world than at decoding tricky optical illusions?
Click to reveal all bullets.

3. Sensation vs. Perception
“The process by which our sensory receptors and nervous system receive and represent stimulus energies from our environment.”
“The process of organizing and interpreting sensory information, enabling us to recognize meaningful objects and events.”
The brain receives input from the sensory organs.
The brain makes sense out of the input from sensory organs.
Click to reveal shortened definition; click again to reveal rest of animation.

4. Making sense of the world
Top-down processing:
using models, ideas, and expectations to interpret sensory information
What am I seeing?
Bottom-up processing:
taking sensory information and then assembling and integrating it
Click to reveal definitions for bottom-up and top-down processing.
Is that something I’ve seen before?

5. Do you see a painting or a 3D bottle? What’s on the bottle?
Kids see eight to ten dolphins.
Why do you think kids see something different than adults?
Click to reveal answer and to circle the dolphins.
Answer to the question: Top-down processing by children uses different experiences and different models; they are likely to have seen more images of dolphins than images of a nude embrace.
Adults also do more top-down processing, and are more likely to “see” objects that aren’t fully there.
This shows that “seeing” involves the process of perception, not just the process of our eyes taking in information.

6. Top-down Processing
You may start to see something in this picture if we give your brain some concepts to apply:
“tree”
“sidewalk”
“dog”
“Dalmatian”
Click to reveal sidebar and hints one by one.

7. From Sensory Organs to the Brain
The process of sensation can be seen as three steps:
Reception--
the stimulation of sensory receptor cells by energy (sound, light, heat, etc)
Transduction-- transforming this cell stimulation into neural impulses
Transmission--delivering this neural information to the brain to be processed
Automatic animation.
Psychophysics refers to the study of the psychological effects of the forms of energy (heat, light, sound) that we can detect.

8. Sensation-Perception
The strange case of Dr. P
Visual Agnosia
seeing without "knowing"
Helen Sellers
Prosopagnosia
face blindness

9. Fusiform area Face recognition Face blindness Prosopagnosia
Greek: “prosopon” ( face)
“ag nosia” (not knowing)
What if face recognition ok, but emotion inputs are disconnected?
CAPRAS SYNDROME: My wife is an imposter!!

10. Oliver Sacks https://www.youtube.com/watch?v=k5bvnX YIQG8
Prosopagnosia
face blindness
YIQG8

11. Sensation-Perception
Agnosias show both sides of “-”
Sensation transduction/assembly
Perception recognition/meaning
Importance of S-P research
ancient philosophical riddle: What is reality?
clinical and practical applications
Sensory disorders
Problems of daily living (e.g. accidents)

12. 3 Approaches to Sens-Percep
Psychophysical
Physiological
Cognitive

13. Psychophysics Quantifying sensation Gustav Fechner (1860)
How much energy needed before detection?
What does "twice" as loud mean?
Gustav Fechner (1860)
Absolute threshold (50% likelihood of being detected)

14. Anything below this threshold is considered “subliminal.”
Thresholds
The absolute threshold refers to the minimum level of stimulus intensity needed to detect a stimulus half the time.
Anything below this threshold is considered “subliminal.”
No animation.
Instructor: You could first present this question using a specific sense, such as “How loud does a sound have to be before you can detect it?”

15. Psychophysics Gustav Fechner (1860)
JND= Just Noticable Difference
Q: What is the JND for light?
Q: What is the JND for sound?
Any general law for intensity scaling?
Weber's Law:
Intensity = constant proportion of initial stimulus

16. Introducing Psychology
11/19/2018
Weber Fraction
e.g., JND for light = 1/60 watts
General scaling of "intensity“
Fechner: Use #JNDs above absolute
Stevens (1960s): “Power Law”
Magnitude ratings
Fit mathematical curves
Best fitting exponent for each sense
where I is the magnitude of the physical stimulus, ψ(I) is the subjective magnitude of the sensation evoked by the stimulus, a is an exponent that depends on the type of stimulation and k is a proportionality constant that depends on the units used.
Criticism:
It has also been questioned, particularly in terms of signal detection theory, whether any given stimulus is actually associated with a particular and absolute perceived intensity; i.e. one that is independent of contextual factors and conditions. Consistent with this, Luce (1990, p. 73) observed that "by introducing contexts such as background noise in loudness judgements, the shape of the magnitude estimation functions certainly deviates sharply from a power function"
©2001 Prentice Hall

17. When Absolute Thresholds are not Absolute
Signal detection theory refers to whether or not we detect a stimulus, especially amidst background noise.
This depends not just on intensity of the stimulus but on psychological factors such as the person’s experience, expectations, motivations, and alertness.
No animation.
For example, parents of newborns can detect a faint baby’s cry that for others would not stand out from background noise.

18. Signal Detection Theory (SDT)
Detection is rarely absolute because
Stimulus certainty varies (e.g., noise)
Motivation varies (e.g., boredom)
Signal Detection Theory (SDT)
Hits + / +
Correct Rejections - / -
Misses - / +
False Alarms + / -

19. Signal Detection Theory (SDT)
Detection rate controlling response bias
Takes into account statistical nature of detection
Takes into account psychological factors affecting detection

20. Signal Detection Theory (SDT)
Introducing Psychology
11/19/2018
Signal Detection Theory (SDT)
In medical diagnosis which signal detection outcome is most critical?
Hits
Misses
False Alarms
Correct rejections
©2001 Prentice Hall

21. Signal Detection Theory (SDT)
In the judicial system which signal detection outcome is most critical?
Hits
Misses
False Alarms
Correct rejections

22. Martinez-Conde et al. (2006)
Sensory Adaptation
Entering movie theatre (vision)
Visiting friend's apartment (smell)
Change detection is evolutionarily critical
Why don't visual images fade?
Saccades eye movements
Pritchard (1961)
Martinez-Conde et al. (2006)

23. Sensory Adaptation
Even visual perception of emotional expressions show evidence of sensory adaptation….

28. Gaze at the angry face on the left for 20 to 30 seconds, then look at the center face (looks scared, yes?). Then gaze at the scared face on the right for 20 to 30 seconds, before returning to the center face (now looks angry, yes?). (From Butler et al., 2008.)

29. Introducing Psychology
11/19/2018
20 grams of fat =
2 Big Macs
©2001 Prentice Hall

30. Subliminal Perception
Sub + Limen
Advertising: e.g., "Joe Camel"

31. Joe Camel Advertising Campaign
% who start smoking > 18?
Less than 5%
Well, then…..Get ‘em when they’re young!!
Use cartoon characters
Use subliminal sex cues

32. 888 million $$$$ Joe Camel ad campaign 1988 sales (to juveniles)
$$ Ka-ching.
$$$$

34. Big Tobacco & Subliminal Percep.

40. Subliminal Perception
Silverman (1988)
Use subliminal msg. to test Freudian ideas
“Dynamic Activation Method”
Tachistoscope
“Mommy and I Are One”
RESULT? Positive mood/wellbeing
“Beating Dad is OK”
RESULT? Dart throwing accuracy

41. Begg et al (1993) Greenwald et al. (1991)
Rock band Judas Priest, lawsuit: “Do it!”
Experiment : backward song effect??
No comprehension.
No effect on behavior.
Greenwald et al. (1991)
Self-esteem; Memory enhancement
Gave wrong tape to half of sample.
Measured actual self-steem, and memory
Believed it worked---even if wrong tape!!
NO effect on self-esteem, or memory.

42. Subliminal Perception
Krosnick et al. (1992)
subliminal prime (dead bodies vs flowers)
rate persons in photographs
Result? primes affected ratings
Yes, subliminal primes can work.
But very weak, very brief.

43. ESP
Unknown sensory systems?
Telepathy
Clairvoyance
Precognition

44. Does ESP exist? JB Rhine (Duke University): 1934 book Zenner Cards
Guess the symbols!
Telepathy (sender)
Clairvoyance (face down)
Precognition (predict)
Results:
RESULT: Yes, > chance!
Wow! Maybe ESP is real ???

45. ESP: Bem & Hornton (1994 ) Gansfeld Procedure Psych Bulletin (1994
Sensory masking
Talk aloud about what floats through one’s mind
Present 4 objects
Which one correct?
Psych Bulletin (1994
32% correct! > chance correct rate (25%)

46. Bem (2011) “Feeling the Future”
Extrasensory Pornception
Neutral? Chance levels (no effect).
Erotic images?
53% accuracy!!

47. Bem (2011) “Feeling the Future”
No one has been able to replicate Bem’s result. Maybe it was bad stats and reviewers overly awed by the lead researcher, eminent soc psyc Daryl Bem.

48. Sensory Systems Thalamus (except smell) Cortex  association areas
Sensory neurons: transduction
Nerves--> spinal cord--> brain
Thalamus (except smell)
Cortex  association areas
… retrieval, comparison, categorization...recognition,
Recognition !
Do something.

49. Introducing Psychology Vision
11/19/2018
Vision
Prepared by Michael J. Renner, Ph.D.
These slides ©2001 Prentice Hall Psychology Publishing.
©2001 Prentice Hall

50. Electromagnetic Radiation Spectrum
(e.g., Newton, Faraday, Maxwell...)

51. Visual Spectrum
390nm
700nm

52. The Eye
“…To suppose that the eye, with all its inimitable contrivances for adjusting the focus to different distances, for admitting different amounts of light, and for the correction of spherical and chromatic aberration, could have been formed by natural selection, seems I freely confess, absurd in the highest degree. "
Darwin, 1859

55. A B

56. Basic Structures of The Eye
Pupil
Regulates amount of light entering the eye.
Emotions, expectations, and autonomic nervous system can induce pupil dilation or contraction
Lens
Accommodation
The action of ciliary muscles to change the thickness of the lens

57. Duplex Vision: Rods and Cones

58. Which has no rods?
A: OWL
B: CHIPMUNK

59. The Retina 1) Rod cells Sensory neurons of the visual system
Extension of the brain
The sensory neurons for vision are there.
Sensory neurons of the visual system
1) Rod cells
Back & white vision
125 million rod cells
high convergence (many rods connect to 1 ganglion cell)
v. sensitive to low light (eg, Owls)

60. Sensory neurons of the retina
2. Cone cells
Color vision (3 cone types: RGB)
6 million (all in the Fovea)
Low convergence (1 to 1 ganglion cell)
Chipmunks (all cones; no rods)

61. Structure of the Retina (cont'd)
Fovea
small spot, middle of retina
cones only (no rods)
Bipolar cells
Ganglion cells
axons --> "optic nerve"
Horizontal & Amacrine cells
"preprocessor"
Frog: "bug detector"

62. Retina

63. Retina layers

64. Receptive Fields (center-surround)

65. Lateral antagonism firing of a cell inhibits firing of adjacent cells
permits coding of contrasts
Explains Hermann Grid Ilusion...

67. Dark / Light Adaptation
Rods
slow to adapt (30 mins)
10,000 x more sensitive to light
Cones
fast to adapt (10 mins)
focal vision back quickly

68. LGN (lateral geniculate nucleus)
Visual Pathways
Thalamus
LGN (lateral geniculate nucleus)
Midbrain
Superior Colliculus

70. Thalamus
LGN (lateral geniculate nucleus)
Midbrain
Superior Colliculus

71. Visual Pathways to the Brain
LGN (Lateral Geniculate Nucleus)
Parvocellular layer (90%)
form, texture, color
Magnocellular layer (10%)
depth, brightness, motion
Koniocellular layer
some aspects of color perception

72. Lateral Geniculate Nucleus Parvocellular layers Magnocellular layers 6
90% of retinal ganglion cells send axons to LGN 6 5 4 3
Parvocellular
layers 2 1
Magnocellular
layers

73. Superior Colliculi Function:
Head, eye movements (e.g., movement tracking)
Integrate visual info with other senses (e.g., touch, hearing)
Midbrain

74. Optic radiations

75. Primary Visual Cortex ( “V1” )

77. (Vision for Action Pathway) (Vision for Perception Pathway)
“Where, How?”
(Vision for Action Pathway)
Dorsal Stream
Association areas
Primary Visual Cortex
(Vision for Perception Pathway)
Ventral Stream
Association areas
“What?”

78. Superior Colliculi also play a role in “Where / How” visual processing

79. Visual Pathway and Visual Cortex