1. Sensation Vision Hearing The Stimulus Input: Light Energy The Eye
Visual Information Processing
Color Vision
Hearing
The Stimulus Input: Sound Waves
The Ear
Hearing Loss and Deaf Culture

2. Vision

3. Transduction
In sensation, the transformation of stimulus energy into neural impulses.
Phototransduction: Conversion of light energy into neural impulses that the brain can understand.
OBJECTIVE 4| Define transduction, and specify the form of energy our visual system converts into neural messages our brain can interpret.

4. The Stimulus Input: Light Energy
Visible
Spectrum
Both Photos: Thomas Eisner

5. Light Characteristics
Wavelength (hue/color)
Intensity (brightness)

6. Wavelength (Hue)
Hue (color) is the dimension of color determined by the wavelength of the light.
Wavelength is the distance from the peak of one wave to the peak of the next.

7. Different wavelengths of light result
Wavelength (Hue)
Violet
Indigo
Blue
Green
Yellow
Orange
Red
400 nm
700 nm
Short wavelengths
Long wavelengths
Different wavelengths of light result
in different colors.

8. Intensity (Brightness)
Intensity Amount of energy in a wave determined by the amplitude. It is related to perceived brightness.

9. Intensity (Brightness)
Blue color with varying levels of intensity.
As intensity increases or decreases, blue color
looks more “washed out” or “darkened.”

10. The Eye
OBJECTIVE 5| Describe the major structure of the eye, and explain how they guide the incoming ray of light toward the eye’s receptor cells.

11. Parts of the eye
Cornea: Transparent tissue where light enters the eye.
Pupil: The shutter like opening through which light passes through to the lens.
Iris: Muscle that expands and contracts to change the size of the opening (pupil) for light.
Lens: Focuses the light rays on the retina.
Retina: Contains sensory receptors that process visual information and sends it to the brain.

12. Acuity
Nearsightedness: A condition in which nearby objects are seen more clearly than distant objects.
Farsightedness: A condition in which faraway objects are seen more clearly than near objects.

13. Retina
Retina: The light-sensitive inner surface of the eye, containing receptor rods and cones in addition to layers of other neurons (bipolar, ganglion cells) that process visual information.
OBJECTIVE 6| Contrast the two types of receptor cells in the retina, and describe the retina’s reaction to light.

14. Photoreceptors
E.R. Lewis, Y.Y. Zeevi, F.S Werblin, 1969

15. Bipolar & Ganglion Cells
Bipolar cells receive messages from photoreceptors and transmit them to ganglion cells, which are for the optic nerve.

16. Optic Nerve, Blind Spot & Fovea
Optic nerve: Carries neural impulses from the eye to the brain. Blind Spot: Point where the optic nerve leaves the eye because there are no receptor cells located there. This creates a blind spot. Fovea: Central point in the retina around which the eye’s cones cluster.

17. Test your Blind Spot
Use your textbook. Close your left eye, and fixate your right eye on the black dot. Move the page towards your eye and away from your eye. At some point the car on the right will disappear due to a blind spot.

18. Visual Information Processing
Optic nerves connect to the thalamus in the middle of the brain, and the thalamus connects to the visual cortex.
OBJECTIVE 7| Discuss the different levels of processing that occur as information travels from the retina to the brain’s cortex.

19. Hubel and Wiesel: Feature Detection
Nerve cells in the visual cortex respond to specific features, such as edges, angles, and movement.
Ross Kinnaird/ Allsport/ Getty Images

20. Visual Information Processing
Processing of several aspects of the stimulus simultaneously is called parallel processing. The brain divides a visual scene into subdivisions such as color, movement, form and depth etc.
OBJECTIVE 8| Discuss parallel processing and discuss its role in visual processing.

21. Theories of Color Vision
Trichromatic Theory
Opponent Process Theory

22. Trichromatic theory: Based on behavioral experiments, Helmholtz suggested that the retina should contain three receptors that are sensitive to red, blue and green colors.
Standard stimulus
OBJECTIVE 9| Explain how the Young-Helmholtz and opponent-process theories help us understand color vision.
Comparison stimulus
Max
Medium
Low
Blue
Green
Red

23. Subtraction of Colors
If three primary colors (pigments) are mixed, subtraction of all wavelengths occurs and the color black is the result.

24. Addition of Colors
If three primary colors (lights) are mixed, the wavelengths are added and the color white is the result.
Fritz Goro, LIFE magazine, © 1971 Time Warner, Inc.

25. Color Blindness
Genetic disorder in which people are blind to green or red colors. This supports the Trichromatic theory.
Ishihara Test

26. Opponent Process Theory
Hering proposed that we process four primary colors combined in pairs of red-green, blue-yellow, and black-white.
Cones
Retinal
Ganglion
Cells

27. Opponent Colors Gaze at the middle of the flag for about 30
Seconds. When it disappears, stare at the dot and report
whether or not you see Britain's flag.

28. Color Constancy
Color of an object remains the same under different illuminations. However, when context changes the color of an object may look different.
OBJECTIVE 10| Explain the importance of color constancy.
R. Beau Lotto at University College, London

29. Audition (Hearing)

30. The Stimulus Input: Sound Waves
Sound waves are composed of compression and expansion of air molecules.
OBJECTIVE 11| Describe the pressure waves we experience as sound.
Acoustical transduction: Conversion of sound waves into neural impulses in the hair cells of the inner ear.

31. Sound Characteristics
Wavelength or Frequency (pitch)
Amplitude or Intensity (loudness)

32. Frequency (Pitch)
Frequency (pitch): The dimension of frequency determined by the wavelength of sound.
Wavelength: The distance from the peak of one wave to the peak of the next.

33. Intensity (Loudness)
Intensity or Amplitude (Loudness): Amount of energy in a wave, determined by the amplitude, relates to the perceived loudness.

34. Loudness of Sound
Richard Kaylin/ Stone/ Getty Images
120dB
70dB

35. The Ear
Dr. Fred Hossler/ Visuals Unlimited
OBJECTIVE 12| Describe the three regions of the ear, and outline the series of events that triggers the electrical impulses sent to the brain.

36. The Ear Outer Ear: Pinna-Collects sound waves.
Auditory Canal- channels sound waves toward ear drum
Eardrum- tight membrane that vibrates with the waves

37. The Ear
Middle Ear: Chamber between eardrum and cochlea containing three tiny bones that concentrate the vibrations of the eardrum on the cochlea’s oval window.
hammer (Malleus)
anvil (Incus)
stirrup (Stapes)

38. The Ear Inner Ear: Innermost part of the ear.
Cochlea – incoming vibrations on the oval window (membrane) cause the fluid that fills the snail-shaped tube to be jostled.
Basilar Membrane- lined by hair cells/ cilia that ripple with the motion. The movement of the hair cells triggers an impulse for adjacent nerve cells.
Auditory Nerve- the nerve cells that converge to send messages to the thalamus and on to the auditory cortex.

39. Cochlea
Cochlea: Coiled, bony, fluid-filled tube in the inner ear that transforms sound vibrations to auditory signals.

40. Theories of Audition
Place Theory suggests that sound frequencies stimulate the basilar membrane at specific places resulting in perceived pitch.
OBJECTIVE 13| Contrast place and frequency theories, and explain how they help us to understand pitch perception.

41. Theories of Audition
Frequency Theory states that the rate of nerve impulses traveling up the auditory nerve matches the frequency of a tone, thus enabling us to sense its pitch.
Auditory Nerve
Action Potentials
Sound
Frequency
200 Hz
100 Hz

42. Localization of Sounds
Because we have two ears, sounds that reach one ear faster than the other ear cause us to localize the sound.
OBJECTIVE 14| Describe how we pinpoint sounds.

43. 1. Intensity differences
Localization of Sound
1. Intensity differences
2. Time differences
Time differences as small as 1/100,000 of a second can cause us to localize sound. The head acts as a “shadow” or partial sound barrier.

44. Hearing Loss
Conduction Hearing Loss: Hearing loss caused by damage to the mechanical system that conducts sound waves to the cochlea.
Sensorineural Hearing Loss: Hearing loss caused by damage to the cochlea’s receptor cells or to the auditory nerve, also called nerve deafness.
OBJECTIVE 15| Contrast two types of hearing loss, and describe some of their causes.

45. Deaf Culture
Cochlear implants are electronic devices that enable the brain to hear sounds.
OBJECTIVE 16| Describe how cochlear implants function, and explain why Deaf culture advocates object to these devices. Where these implants are pertinent for hearing parents with deaf children, deaf culture advocate not using them especially on children deafened before learning to speak.
Wolfgang Gstottner. (2004) American
Scientist, Vol. 92, Number 5. (p. 437)
EG Images/ J.S. Wilson ©
Deaf Musician
Cochlear Implant

46. Sensation Other Important Senses Touch Taste Smell
Body Position and Movement

47. Other Important Senses
The sense of touch is a mix of four distinct skin senses—pressure, warmth, cold, and pain.
OBJECTIVE 17| Describe the sense of touch. “Touch is both the alpha and omega of affection” (James, 1890).
Bruce Ayers/ Stone/ Getty Images

48. Skin Senses
Only pressure has identifiable receptors. All other skin sensations are variations of pressure, warmth, cold and pain.
Pressure
Vibration
Vibration
Burning hot
Cold, warmth and pain

49. Ashley Blocker (right) feels neither pain
Pain tells the body that something has gone wrong. Usually pain results from damage to the skin and other tissues. A rare disease exists in which the afflicted person feels no pain.
OBJECTIVE 18| State the purpose of pain, and describe the biopsychosocial perspective on pain.
AP Photo/ Stephen Morton
Ashley Blocker (right) feels neither pain
nor extreme hot or cold.

50. Gate-Control Theory
Melzak and Wall (1965, 1983) proposed that our spinal cord contains neurological “gates” that either block pain or allow it to be sensed.
One way to treat chronic pain is to stimulate it through massage by electrical stimulation or acupuncture. Rubbing causes competitive stimulation to pain thus reduces its effect.
Gary Comer/ PhototakeUSA.com

51. Pain Control
Pain can be controlled by a number of therapies including, drugs, surgery, acupuncture, exercise, hypnosis, and even thought distraction.
Burn victims can be distracted by allowing them to engage in illusory virtual reality. Their brain scans show differences in pain perceptions.
Todd Richards and Aric Vills, U.W.
©Hunter Hoffman,

52. Taste
Traditionally, taste sensations consisted of sweet, salty, sour, and bitter tastes. Recently, receptors for a fifth taste have been discovered called “Umami”.
OBJECTIVE 19| Describe the sense of taste, and explain the principle of sensory interaction.
Sweet
Sour
Salty
Bitter
Umami
(Fresh
Chicken)

53. Sensory Interaction
When one sense affects another sense, sensory interaction takes place. So, the taste of strawberry interacts with its smell and its texture on the tongue to produce flavor.

54. Smell
Like taste, smell is a chemical sense. Odorants enter the nasal cavity to stimulate 5 million receptors to sense smell. Unlike taste, there are many different forms of smell.
OBJECTIVE 20| Describe the sense of smell and explain why specific odors so easily trigger memories.

55. Smell and Memories
The brain region for smell (in red) is closely connected with the brain regions involved with memory (limbic system). That is why strong memories are made through the sense of smell.

56. Body Position and Movement
The sense of our body parts’ position and movement is called kinesthesis. The vestibular sense monitors the head (and body’s) position.
OBJECTIVE 21| Distinguish between kinesthesis and vestibular sense.
Bob Daemmrich/ The Image Works
Whirling Dervishes
Wire Walk