1. Sensation and Perception

3. Sensation
The process by which our sensory systems (eyes, ears, and other sensory organs) and nervous system receive stimuli from the environment

4. Sensation Input comes from the five senses: Visual (Eyes) Audio (Ears)
Cutaneous/Tactile (Touch)
Olfaction (Smell) (Nose)
Gustation (Taste) (Tongue)

5. Receptor Cells
Each of the five senses is specifically coded to only take in one type of stimulus, whether is be light waves, sound waves, smell, taste, or touch.

6. The process of organizing and interpreting sensory information
Perception
The process of organizing and interpreting sensory information
How we recognize, interpret, and organize our sensations

7. Bottom-Up Processing
Information processing that focuses on the raw material entering through the eyes, ears, and other organs of sensation
This is the sensation part of awareness

9. Top-Down Processing
Information processing that focuses on expectations and experiences in interpreting incoming sensory information
This is the perception part of your awareness

10. Top Down Processing can lead to errors!

11. do you see the tiger. (top down) do you see the hidden tiger
do you see the tiger? (top down) do you see the hidden tiger? (bottom up)

12. do you see the mountains? (top down) do you see the face? (bottom up)

13. Thresholds
Module 9: Sensation

14. Absolute Threshold A threshold is an edge or a boundary
For sensations, it is the point where you either sense a stimulus or don’t
Technically, its “The minimum stimulus that a person can detect 50% of the time”

15. Absolute Detection Threshold
The minimum intensity of energy required to produce sensation in a receptor cell
Taste: 1 gram of table salt in 500 liters of water

16. Smell: 1 drop of perfume diffused throughout a three room apartment

17. Touch:. The wing of a bee falling on your cheek
Touch: The wing of a bee falling on your cheek from a height of 1 centimeter
Hearing: The tick of a watch from 6 meters away

18. Vision: A candle flame on a clear night, 30 miles away

19. One testable way to determine the thresholds for various people is through SIGNAL DETECTION
Incremental changes in sound, taste, etc. are made to test for reactions in people. Tone tests (hearing) are an example.

20. Signal Detection Results
Hit
signal present and sensed
Miss
signal present but not sensed
False Alarm
signal absent, but sensed
Correct Rejection
signal absent, and not sensed

21. IE. Frog eye’s have receptor cells that fire only in response to small, dark, moving objects. Theoretically, a frog would starve to death while knee-deep in motionless flies.

22. Remember……………ABSOLUTE means we either see it, smell it, taste it…
Remember……………ABSOLUTE means we either see it, smell it, taste it….or we don’t!

23. Difference Threshold
The minimum difference that a person can detect between two stimuli 50% of the time
Also called just noticeable difference
(JND)
Hey! Is it just me or did suddenly get a little brighter in here?!
someone must have turned on another light!

24. Ernst Weber and Weber’s Law
The greater the magnitude of the stimulus, the larger the difference must be in order to be noticed
IE. If you are carrying 20 lbs. and add 5 lbs., it’s noticeable. If you are carrying 100 pounds and add 5 pounds, it may not be noticeable. You need to add 10 lbs. to 100 pounds to make it noticeable.

25. Transduction
The process by which a form of physical energy is converted into a coded neural signal that can be processed by the nervous system.

26. Sensory Adaptation
When exposed to a stimuli over a period of time there will be a diminished sensitivity to it
If a stimulus is constant and unchanging, eventually a person may fail to respond to it

27. Example of Sensory Adaptation
A hot tub – after a certain period of time no longer seems as hot

28. Let’s see how good your senses are!
TAKE THE AWARENESS TEST ON THE NEXT SLIDE!

30. Selective Attention
Focusing conscious awareness on a particular stimulus (sense) to the exclusion of others
The ability to focus on one stimulus at a time
Allows a person to function in a world filled with many stimuli

31. Selective Attention Example
Walking down the hallway – all 5 senses are firing. What grabs your attention?

32. Selective hearing
Do you think it exists?

33. The Visual System: The Structure of the Visual System
Module 9: Sensation

34. Parts of the Eye – Blind Spot

35. The Structure of the Visual System
Cornea
Iris
Pupil
Lens

36. Retina
Light-sensitive surface with cells that convert light energy to nerve impulses
At the back of the eyeball

38. Receptor Cells
In sight they change light into neural impulses the brain can understand.
Visual system has two types of receptor cells – rods and cones

39. Rods Visual receptor cells located in the retina
Can only detect black and white
Respond to less light than do cones

40. Cones Visual receptor cells located in the retina
Can detect sharp images and color
Need more light than the rods
Many cones are clustered in the fovea.
Cones

41. Fovea The central focal point of the retina
The spot where vision is best (most detailed)

42. Optic Nerve
Nerve that carries visual information from the eye to the occipital lobes
There are no rods and cones where the nerve exits the eye.
So there is a small blind spot in vision.

44. Retinal Implant

45. Nearsighted - Myopia

46. Farsighted - Hyperopia

47. The Visual System: Color Vision
Module 9: Sensation

48. There are two theories of color vision: Trichromatic Theory
Opponent-Process Theory

49. Can you see what is in the middle?

50. Trichromatic Theory Young-Helmholtz Theory
Cones are pre-set to be sensitive to RED, GREEN, and BLUE. All of the colors that we see are combinations of those three colors.

51. All other colors can be derived by combining these three.
Figure 3.9 from:
Kassin, S. (2001). Psychology, third edition. Upper Saddle River, NJ: Prentice Hall.
All other colors can be derived by combining these three.

52. Color Deficient Vision
People who lack one of the three types of cones
Usually the red or green receptors are missing
Usually referred to as color blindness
In inherited and found more in males

53. Red-Green Color Blindness

54. Opponent-Process Theory
Sensory receptors in the retina come in pairs:
Red/Green
Yellow/Blue
Black/White
Only one side is “on” at a time

55. Opponent Process Theory
ON” “OFF”
red green
green red
blue yellow
yellow blue
black white
white black

56. Afterimage Effect

66. Opponent-Process Theory
If one sensor is stimulated, the other is inhibited
If one sensor is over-stimulated, and fatigues, the paired sensor will be activated, causing an afterimage

67. Hearing: The Nature of Sound
Module 9: Sensation

68. Sound Sound, like light, comes in waves Sound is vibration
Features of sound include:
Pitch
Hertz
decibels

69. Pitch
A sound’s highness or lowness in tone
Dependent on the frequency of the sound wave – the more “waves per second” the higher the frequency or pitch
Is measured as hertz (Hz)

71. Hertz (Hz)
A measure of the number of sound wave peaks per second; measures “frequency”
Determines the pitch of the sound
Human hearing goes from 20 Hz to 20,000 Hz

72. Low Pitch Wave peaks are far apart
Human hearing goes from 20 Hz to 20,000 Hz although some ears (and speakers) are better than others

73. High Pitch As pitch increases, so do the number of waves
Remember - Human hearing goes from 20 Hz to 20,000 Hz note: a kilohertz is 1,000 hertz so 20 kilohertz equals 20,000 hertz

74. Decibel (dB) A measure of the height of the sound wave
Determines the loudness of the sound
Sometimes called amplitude

76. Hearing: The Structure of the Auditory System
Module 9: Sensation

77. Divisions of the Ear

78. The Structure of the Auditory System
Pinna / Auricle
Auditory Canal
Eardrum
Ossicles
Hammer, Anvil, Stirrup

79. Oval Window
The point on the cochlea which receives the sound vibration from the ossicles
As the oval window vibrates, the fluid in the cochlea vibrates.

80. The Ossicles amplify the vibration of the eardrum
Oval Window
The Ossicles amplify the vibration of the eardrum

81. Cochlea
Where sound waves are changed into neural impulses (transduction)
A snail shell shaped tube
Filled with fluid

82. Hair Cells
The receptor cells for hearing in the cochlea that change sound vibrations into neural impulses
Transduction!

83. Movement of the fluid causes the hair cells to move which causes TRANSDUCTION!

86. Auditory Nerve
The nerve that carries sound information from the ears to the temporal lobes of the brain

87. EUSTACHIAN TUBE
A tube that connects the middle ear to the back of the nose; it equalizes the pressure between the middle ear and the air outside. When you "pop" your ears as you change altitude (going up a mountain or in an airplane), you are equalizing the air pressure in your middle ear.

88. Semicircular Canals
Organs in the inner ear used in sensing body orientation and balance (vestibular sense)

89. Vestibular Sense
Relies on fluid in the semicircular canals of the inner ear
Spinning in circles disrupts the fluid.

91. How do we hear?
Place Theory- different frequencies in sound waves cause vibrations at
Low Frequencies
High Frequencies
different places in the cochlea

92. Frequency Theory- different frequency of the sound wave vibrates the inner ear at a different rate

93. Hearing: Sound Localization
Module 9: Sensation

94. Localization of Sound Locating where sound is originating from
Done through two cues:
Which ear hears the sound first?
Which ear hears the louder sound?

95. Localization of Sound

96. Problems with hearing Conduction deafness (middle ear damage)
Nerve deafness (hair cell or auditory nerve damage)

97. Cochlear Implant

99. Other Senses: Taste (Gustation)
Module 9: Sensation

100. Taste Taste is a chemical sense.
The receptor cells for taste are the taste buds.

101. Taste Taste is a chemical sense.
The little bumps on our tongues are actually called papillae
Inside some of these papillae are clumps of taste cells.
These clumps of cells are actually the taste buds.

102. Taste On average, adults have about 7,500 taste buds.
These receptor cells are located in the tongue and in the mouth.
When food dissolves on these receptors, TRANSDUCTION occurs
Damaged taste receptor cells are replaced within a few days to 2 weeks

103. Taste Sensations
sweet
sour
salty
bitter
- umami (savory-msg)

105. Supertasters People with an abundance of taste receptors
Approximately 25% of the population

106. Nontasters People with a minimum of taste receptors
Taste with less intensity than the rest of the population
Approximately 25% of the population

107. Other Senses:
Module 9: Sensation

108. Smell Smell is a chemical sense.
Olfactory receptors/cells in the upper nasal passages detect molecules in the air.
Taste and smell interact to produce flavor.

110. Other Senses: Touch

111. Touch Touch receptors are on the skin Four basic skin senses are Pain
warmth
cold
pressure
All skin sensations are a combination of these four basic senses

113. Sensitivity of Diff body to pain
Most Sensitive
Back of knees
Neck region
Bend of elbow
Least Sensitive
Tip of the Nose
Sole of foot
Ball of thumb

114. Pain messages travel on one set of nerve fibers containing pain gates.
The gates are open when pain is felt.
Other sensory messages go through another set of fibers.
The non-pain fibers can close the pain gates to stop the sense of pain.

115. Suppressing Pain (this is a link…in case its not working….)

116. Other Sense: Body Senses
Module 9: Sensation

117. Kinesthetic Sense
The system for sensing the position and movement of individual body parts
Relies on receptor cells from the muscles and joints
One’s leg “falling asleep” is a disruption of the kinesthetic sense

118. The End