1. Sensation https://www.youtube.com/watch?v=unWnZvXJH2o
Module 09

2. Let’s see if you labeled correctly:

5. Let’s take in our surroundings:
What do you see?
What shapes are around you? What colors?
What sounds are you listening to?
What can you feel?
Is your clothing comfortable, what about your chair?
What do you taste?
Are there any odors?
This awareness of the world around you is called sensation.

6. Sensation Bottom-up processing:
The process by which our sensory systems (eyes, ears, and other sensory organs) and nervous system receive stimuli from the environment
Bottom-up processing:
Information processing that focuses on the raw material entering through the eyes, ears, and other organs of sensation

7. Perception
The process of organizing and interpreting sensory information
Top-Down Processing:
Information processing that focuses on expectations and experiences in interpreting incoming sensory information

8. Sensation and Perception
Do you see some marks that look the same as others, but are meant to be interpreted differently?
Sensation brings image from paper to your brain, a bottom-up process of gathering environmental info through the senses.
Perception involves knowing what to make of the individual marks in the sentence. This top-down interpretation relies on your experiences with, and expectations about, language.

9. Thresholds: an edge or a boundary
What are absolute thresholds
and difference thresholds,
and how do they differ?

10. Absolute & Difference Threshold
Absolute threshold:
The minimum stimulation needed to detect a particular stimulus.
Ex: Dimmest star in the sky would be right at the absolute threshold for vision.
What about for taste/hearing?
Difference threshold
Aka: just noticeable difference
Minimum difference that a person can detect b/t 2 stimuli.
The smallest detectable change in a stimulus.
When does sound become too loud or when is something too tight?

11. Sensory Adaptation How does sensory adaptation make your life easier?
When we filter out the non-changing aspects of our environment.
If a stimulus is constant and unchanging, eventually a person may fail to respond to it.
Diminished sensitivity as a result of constant stimulation.
EX: getting into a swimming pool that seems rather chilly
What happens at first? After a while?
EX: ever look for your sunglasses and realize they are on your head?

12. Selective Attention How does selective attention relate to effective study skills?
Focusing conscious awareness on a particular stimulus to the exclusion of others
You can’t pay attention to every single little thing at once!
The ability to focus on one stimulus at a time
Ever blocked out sound to help you study/sleep?
Allows a person to function in a world filled with many stimuli

13. So… what do you see? You can attend to one view or the other:
Old or young woman
You can earn learn to switch back and forth.
You cannot see both images at once.

14. The Visual System: The Nature of Light What is light?
Module 9: Sensation

15. Electromagnetic Energy
Light enters the eye as waves of electromagnetic energy.
An energy spectrum that includes X-rays, radar, and radio waves .
A small portion of the spectrum includes light visible to the human eye

16. The Electromagnetic Spectrum
Light is a form of electromagnetic energy. This energy travels in waves, ranging from short gamma rays to long radio waves. The human eye can detect only a small portion of these waves, the visible spectrum, as light.

17. 1st characteristic of waves: Hue
The color of light as determined by the wavelength of the light energy
What color is this power point slide?
Includes: red, orange, yellow, green, blue, indigo and violet (ROY G BIV)
The eye can detect 7 million separate hues

18. Wavelength

19. 2nd characteristic of waves: Amplitude
The brightness of light as determined by height of the wave
The taller the wave, the brighter the color
Thus greater amplitude stronger hue.

20. The Visual System: The Structure of the Visual System What are the major parts of the visual system, and what roles do these parts play in our ability to see?
Module 9: Sensation

21. Cornea Light first strikes the cornea!
The clear bulge on the front of the eyeball
Begins to focus the light by bending it toward a central focal point
Protects the eye

22. Iris
Colored part
A ring of muscle tissue that forms the colored portion of the eye
Regulates the size of the pupil by changing its size--allowing more or less light to enter the eye

23. Pupil
The adjustable opening in the center of the eye that controls the amount of light entering the eye (surrounded by the iris)
In bright conditions the iris expands, making the pupil smaller.
In dark conditions the iris contracts, making the pupil larger.
Ex: wake up in middle of night go to the bathroom, turn on light and watch your pupil shrink in the mirror.
Restricting light b/c it’s too bright for you.

24. Lens A transparent structure behind the pupil
Focuses the image on the back of the eye (retina)
Muscles that change the thickness of the lens change how the light is bent thereby focusing the image
Lens not letting you focus?
Get contacts/glasses

25. Nearsightedness & Farsightedness
With normal vision, the lens changes in thickness to cause the light rays from a viewed object to converge at the retina.
The result is a clear focused image.
In a nearsighted person’s eye, the lens causes light rays from distant objects to converge in front of the retina, which blurs the image.
If a person is farsighted, the lends causes light rays from close objects to converge behind the retina.
Corrective lenses, help the eye’s own lens focus the image correctly.

26. Retina Made up of three layers of cells Receptor cells Bipolar cells
All other structures (cornea, pupil, iris, lens) direct traffic – move visual info to retina!
Important processing center at the back of the eyeball
Light-sensitive surface with cells that convert light energy to nerve impulses
Made up of three layers of cells
Receptor cells
Bipolar cells
Ganglion cells

27. Retina layer: Receptor Cells
Deepest layer of retina.
Can change light energy into nerve impulses that the brain can interpret.
Without this, the brain would be completely isolated from information in the outside world.
Two different types:
Rods and cones
Visual receptor cells located in the retina.
Different in appearance and function.

28. Comparing and Contrasting: Rods Cones
Can only detect black and white.
Have a lower absolute threshold.
Respond to less light than do cones.
Under dim light, only rods respond and you see the worlds in shades of gray.
Less of them.
Can detect sharp images and color.
Need more light.
Many cones are clustered in the fovea, where your vision is best.

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

31. Two remaining layers of the retina:
Bipolar Cells:
Middle layer of retina.
Gather information from the rods and cones and pass it on to the ganglion cells
Ganglion Cells:
Top layer of retina.
Receive info from bipolar cells and transmit it through their axons, which together form the optic nerve.

32. Visual Processing in the Retina

33. The nerve that carries visual info
The nerve that carries visual info. from the eye to the occipital lobes of the brain.
Optic Nerve

34. Parts of the Eye – Blind Spot (check page 166 in your book)
The point at which the optic nerve travels through the retina to exit the eye.
The lack of receptor rods and cones at this point creates a small blind spot.

35. The Visual System: Color Vision What are the two theories of color vision? Which one offers the best explanation of how we see colors?
Module 9: Sensation

36. #1:Trichromatic (three-color) Theory
Theory of color vision that says cones are “tuned” to be sensitive to red, green and blue light
All the colors we see are a combination of these three colors.
Based on work of Helmholtz and Young
Similar to the design of a color TV

37. Subtractive Color Mixing
When mixing colored paints, each new color SUBTRACTS (soaks up) another wavelength.
Red, blue, and yellow combine to make black paint.
Additive Color Mixing
When mixing colored lights, each new color ADDS another wavelength.
Red, green, and blue combine to make white light.

38. 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
Sometimes people don’t even know the problem exists.

39. #2: Opponent-Process Theory of Color
Ewald Hering’s theory that says color is processed in opponent pairs of color:
Red-green, yellow-blue, black-white
Light that stimulated one half of the pair inhibits the other half
Explains the afterimage effect

40. Afterimage Effect: Stare at the white dot in the middle w/o blinking

41. So…what do you see?

42. Really great video to watch (45 min)

43. Hearing: The Nature of Sound
What is sound??

44. Sound Pitch A sound’s highness or lowness
Dependent on the frequency of the sound wave
Is measured as hertz (Hz)
Sound, like light, comes in waves
Sound is vibration
Features of sound include:
Pitch
Hertz
decibels

45. Hertz (Hz) Decibel (dB)
Determines pitch
A measure of the number of sound wave peaks per second; measures “frequency”
Human hearing goes from 20 Hz to 20,000 Hz
Determines loudness
A measure of the height of the sound wave
Sometimes called amplitude
Named after Alexander Graham Bell.

47. Hearing: The Structure of the Auditory System What are the major components of the auditory system? What is the function of each?
Module 9: Sensation

48. Parts of the Ear – Sound Waves Auditory Canal
The opening through which sound waves travel as they move into the ear for processing
Ends at the tympanic membrane (eardrum)
Parts of the Ear – Sound Waves Auditory Canal

49. Tympanic Membrane (eardrum)
The tissue barrier that transfers sound vibration from the air to the tine bones of the middle ear
Can be damaged by objects in the ear or exceptionally loud noises

50. Parts of the Ear – Tympanic Membrane

51. Three tiny bones that transfer sound waves from the eardrum to the cochlea
Hammer, anvil and stirrup
Ossicles

52. A hearing organ where sound waves are changed into neural impulses
The major organ of hearing
Filled with fluid
snail shaped body tube
Cochlea

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

54. Parts of the Ear – Oval Window

55. Hair Cells
The receptor cells for hearing in the cochlea that change sound vibrations into neural impulses
Similar to the rods and cones within the eye

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

57. Semicircular Canals
Organs in the inner ear used in sensing body orientation and balance (vestibular sense)
Relies on fluid in the canals
Spinning in circles disrupts the fluid.

58. Parts of the Ear – Semicircular Canals

59. Divisions of the Ear Ear’s structure can be divided into:
The outer ear
The middle ear
The inner ear

60. Hearing: Localization of Sound How do you identify where a sound is coming from?
Locating where sound is originating from
Done through two cues:
Which ear hears the sound first?
Which ear hears the louder sound?

61. Other Senses: #1: Taste Taste is a chemical sense.
Receptor cells are located primarily on the tongue and in the mouth.
Four different tastes:
Salty, sweet, sour and bitter
Damaged taste receptor cells are replaced within a few days.

62. Supertasters Nontasters
People with an abundance of taste receptors
Approximately 25% of the population
People with a minimum of taste receptors
Taste with less intensity than the rest of the population
Approximately 25% of the population

63. #2: Smell Smell is a chemical sense.
Olfactory cells in the upper nasal passages detect molecules in the air.
Taste and smell interact to produce flavor.
Olfactory Cells
The chemical receptor cells for smell
Located in the nasal passages

64. Smell

65. Smell

66. #3: Touch Touch receptors are on the skin Four basic skin senses are
Pain, warmth, cold, and pressure
All skin sensations are a combination of these four basic senses

67. Gate-control Theory of Pain
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 nonpain fibers can close the pain gates to stop the sense of pain.

68. Other Senses: Body Senses Kinesthetic Sense Vestibular 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
The system for sensing body orientation and balance
Relies on fluid in the semicircular canals of the inner ear
Spinning in circles disrupts the fluid.