1. Sensation and Perception

2.  What do you feel?  You probably feel your rear against your seat.  Ok, now take a whiff around the room – different odors are entering your nose (hopefully something pleasant)  Now listen really closely, what do you hear?  probably the hum from the computer or that guy next to you breathing heavy  Now try to taste what’s in your mouth.  maybe you can dig out a piece of food from your breakfast or maybe you have that morning breath flavor funk going on.  Regardless, at this moment, in some distorted way, you are using all of your senses.

3. Sensation The process by which our sensory receptors (sense organs) receive stimulus from the environment. What that means is when your body (through our senses) takes in information from everything around us, we are experiencing sensation.

4. Perception The process of organizing and interpreting sensory information

5. So sensation is So sensation is taking the stuff from outside of us and bringing it inside our bodies taking the stuff from outside of us and bringing it inside our bodies and perception is and perception is our body trying to understanding and organizing what we take in. our body trying to understanding and organizing what we take in.

6. Sensation Important Concepts

7. So how does your brain make sense of the world and form what you understand as reality? Bottom-Up Processing (data driven) Bottom-Up Processing (data driven) Our sense of reality starts with our sensations and work up to the brain Our sense of reality starts with our sensations and work up to the brain The brain takes the info from the senses and we develop a sense of reality The brain takes the info from the senses and we develop a sense of reality Top-Down Processing (experience driven) Top-Down Processing (experience driven) Our sense of reality begins with our prior experiences Our sense of reality begins with our prior experiences The brain takes our prior experiences and new current info and together we develop a sense of reality The brain takes our prior experiences and new current info and together we develop a sense of reality (the brain compares what you are currently seeing with what you have experienced before) (the brain compares what you are currently seeing with what you have experienced before)

8. Bottom-Up Processing Detection via Receptor cells (flicker, crackle, Smell Transmission To brain Change of energy Into information Organization and Interpretation Experience, motivation, And expectations (fond Campfire memories, Expectations of warmth And friendship Top-Down Processing Behavior, thoughts And emotions (move nearer, warm hands, Feel comfortable Output Processing (perception) Input (sensation)

9. Bottom-Up Processing Let’s start off with an important term – transduction The process by which our body transforms light, sound, touch, etc. into neural impulses that our brain can understand

10. Transduction Conversion of one form of energy to another. Stimulus energies changed to neural impulses. Light Eyes Transduction Neural messages What you consciously see

11. Sensory Adaptation Diminished sensory sensitivity as a result of constant stimulation. When you first go into a restaurant you probably notice lots of different food smells. However, the longer you stay the less you notice them. The smells don’t disappear – people just become less sensitive to them. Do you feel every sensation going on around you??

12. Can you recall a recent time when, your attention focused on one thing, you were oblivious to something else (perhaps to pain, to someone’s approach, or to background music)?

13. Selective Attention The ability to focus on some bits of sensory information and ignore others Illusionists hope you have very bad selective attention Helps us screen out irrelevant stimuli and focus on relevant information Inattentional Blindness

14. Failing to see visible objects when we are focusing our attention elsewhere

15. An example of selective attention is: The ability to listen to one voice among many. Cocktail Party Effect

16. Sensory Interaction One sense may influence another Smell may influence taste

17. What if we could sense everything? Life would hurt. So we can only take in a window of what is out there. Psychophysics : the study of the relationship between physical stimuli and our psychological experiences to them. – i.e. is blue really blue??

18. Measuring the Senses Psychologists assess the accuracy of the senses in two ways Measuring thresholds signal detection theory Applying the signal detection theory

19. Thresholds Thresholds are the idea that our senses have basic limits. There are two types of thresholds –Absolute threshold –Difference threshold (or just noticeable difference)

20. Absolute Threshold The smallest amount of stimulus that a person can reliably detect The smallest amount of stimulus that a person can reliably detect If you can just barely hear a sound – then that is your absolute threshold for sound If you can just barely hear a sound – then that is your absolute threshold for sound Sight = a candle flame seen at 30 miles on a dark clear night Hearing = the tick of a watch under quiet conditions at 20 feet Taste = 1 teaspoon of sugar in 2 gallons of water Smell = 1 drop of perfume diffused in a small house Touch = the wing of a bee falling on your cheek from a distance of 1 cm Some common thresholds

21. Difference Threshold The smallest amount of change needed in a stimulus before we notice the change Also known as Just Noticeable Difference (jnd) Can you tell the difference??

22. Weber’s Law Used to measure the difference threshold The idea that, to perceive a difference between two stimuli, the change must be proportional to the original intensity of the stimulus –What??? –The more intense the stimulus, the more it will need to change before we notice the difference. Weight – 10% Hearing – 5% Vision – 8% How do businesses use Weber’s Law?? - Movie theater example

23. Signal Detection Theory This theory examines how outside influences effect our sensing of stimuli The theory says … –Absolute thresholds are not really absolute –Things like motivation or physical state can affect what we sense.

24. Signal Detection Theory Cont. It is the belief that people respond differently to the same signal and the same person may detect a particular signal at one time but not another For example – if I am really hungry for meat, I am more likely to smell a hamburger than if I was not –If I think I smell a hamburger, but it is not really there, that is called a false positive (perceiving stimuli that is not there) –If a hamburger is grilling right in front of me but I fail to smell it, that is called a false negative (not perceiving a stimulus that is present) Which one is worse??

25. Subliminal Stimulation Below one’s absolute threshold or conscious awareness. Does this work? Yes and No A few studies did show some small emotional reactivity (called priming a response). However, the effects are subtle and fleeting.

26. Sensations We will be covering the following senses We will be covering the following senses Vision Vision Hearing Hearing Touch Touch Taste Taste Smell Smell Body Position and Movement Body Position and Movement

27. Of The 5 Senses, Which Would You Choose To Lose? Why? http://www.fotosearch.com/comp/IMZ/IMZ166/vmo0128.jpg

28. http:// universe-review.ca/I10-13-senses.jpg

29. Sense What Stimulates Us What Gets Stimulated Hearing Vision Touch Pain Sound Waves Smell Taste Light Waves Potentially harmful stimuli Molecules dissolved in fluid Pressure on Skin Pressure-sensitive hair cells in cochlea of inner ear Light-sensitive rods and cones in retina of eye Sensitive ends of touch neurons in skin Sensitive ends of pain neurons in skin and other tissue Taste cells in taste buds on the tongue Sensitive ends of olfactory neurons in the mucous membranes

30. Touch

31. Touch (Somatosensation) 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 Burning = warmth + cold + pain

32. Pain Why do we experience pain?? –Your body’s way of telling you something has gone wrong Biopsychosocial Perspective on Pain Biological Influence Activity in spinal cord Genetic differences in endorphin production Psychological Influences Attention to pain Learning based on experience Expectations Social-Cultural Influences Presence of others Empathy for others’ pain Cultural expectations Personal Experience Of Pain

33. Why do we feel Pain? 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.

34. Vision

35. http://webvision.med.utah.edu/imageswv/pupil.jpeg www.photo.net http://www.cs.umsl.edu/~sanjiv/cs440/mike_project/retina.gif http://www.fofweb.com/Electronic_Images/onfiles/SciHumPhys11-22c.gif

36. Vision Photoreceptors in our eyes gather light Convert its physical energy into neural messages And send it to the occipital lobe in the brain for decoding and analyzing That’s basically it….

38. 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

39. Parts of the Eye – Cornea

40. Iris A ring of muscle tissue that forms the colored portion of the eye; creates a hole in the center of the iris (pupil) Regulates the size of the pupil by changing its size--allowing more or less light to enter the eye

41. Parts of the Eye - Iris

42. 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.

43. Parts of the Eye - Pupil

44. 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 Glasses or contacts correct problems in the lens’ ability to focus.

45. Parts of the Eye - Lens

46. Retina Light-sensitive surface with cells that convert light energy to nerve impulses At the back of the eyeball Made up of three layers of cells –Receptor cells –Bipolar cells –Ganglion cells

47. Parts of the Eye - Retina

48. Receptor Cells These cells are present in every sensory system to change (transduce) some other form of energy into neural impulses. In sight they change light into neural impulses the brain can understand. Visual system has two types of receptor cells – rods and cones

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

50. 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.

51. Rods and Cones

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

54. Types of Vision

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

56. Blind Spot The point at which the optic nerve travels through the retina to exit the eye There are no rods and cones at this point, so there is a small blind spot in vision.

57. Bipolar Cells Gather information from the rods and cones and pass it on to the ganglion cells Cells that form the middle layer in the retina Pass the information from the bipolar cells through their axons Together these cells form the optic nerve. The top layer of the cells in the retina Ganglion Cells Processing

58. Why Two Eyes? Produces binocular disparity –Constructing three dimensional world out of two dimensional retinal images

59. Transduction Conversion of one form of energy to another. Stimulus energies changed to neural impulses. How is this important when studying sensation? For example: Light energy to vision. Chemical energy to smell and taste. Sound waves to sound. Light Eyes Transduction Neural messages What you consciously see

60. We only use light energy to see.

61. Hue The color of light as determined by the wavelength of the light energy Includes: red, orange, yellow, green, blue, indigo and violet (ROY G BIV) The eye can detect 7 million separate hues

62. Amplitude The brightness of light as determined by height of the wave The taller the wave, the brighter the color

63. What makes up a light wave?

64. Wavelength The distance from the peak of one light wave to the peak of the next. The distance determines the hue (color) of the light we perceive.

66. Intensity The amount of energy in a light wave. Determined by the height of the wave. The higher the wave the more intense the light is. (brightness)

68. How do we see in color? What color is this dragon?

69. ColorColor The dragon is anything but red. The dragon rejects the long wavelengths of light that to us are red- so red is reflected off and we see it. Also, light has no real color. It is just energy turned into color by our eyes It is our mind that perceives the color.

70. Two major color theories! What enables you to perceive color??

71. Young-Helmholtz Trichromatic (three color) Theory Realized that any color can be created by combining the light waves of three primary colors Guessed that we have 3 different types of photoreceptor cells in our eyes. Each with differing sensitivities to different light wavelengths Most colorblind people simply lack cone receptor cells for one or more of these primary colors. – Not really blind – just limited in what colors they can see Click here to simulate color blindness Click here to simulate color blindness

72. Opponent-Process Theory The visual system has receptors that react in opposite ways to three pairs of colors (red-green, blue-yellow, and white-black). –These are antagonist/ opponent colors. –Light that stimulates one half of the pair inhibits the other half –Produces afterimages Afterimages Afterimages – colors perceived after other, complementary colors are removed

74. Afterimage Effect

76. Sensory Disorder Synesthesia Anosmia The boy who sees without eyes