2. Sensation and Perception

3. Sensation The stimulation of sense organs or sensory neurons. The sending of “raw data” to the brain by sense organs (eyes, nose, ears, skin, tongue). This is “bottom up” processing.

4. Perception The selection, organization and interpretation of sensory input. Perception gives meaning to sensation. Our reality equals our perception This is “top down” processing.

5. Need some examples of sensation vs. perception?

6. Sensing the warmth of a fire vs. perceiving being near the fire. Sensing the light reflected by an object vs. perceiving an OBJECT Sensing your cell phone vibrate vs. perceiving it is your phone Sensing the sound vs. perceiving your music playing Sensing the light outside coming from the sun vs. perceiving that its warm outside Sensing the alarm going off vs. perceiving your alarm clock. Sensing a loud ring vs. perceiving that its your door bell Sensing the taste of a burger vs. perceiving that it is beef

7. What if we could sense everything? Life would hurt. So we can only take in a window of what is out there. This is the study of psychophysics: relationship between physical stimuli and our psychological experiences to them.

8. So, sensing begins… With sensory receptors:With sensory receptors: dendrites of specialized neurons (afferent), stimulated by different forms of energy in the environment. A STIMULUSA STIMULUS (any detectable input from the environment). DETECTABLE?WHAT in our environment is DETECTABLE? Different for dogs than humans (think what a dog can smell versus what a human can smell. THRESHOLD THRESHOLD is the dividing point between energies that DO or DO NOT have a detectable effect.

9. Absolute Threshold The minimum stimulation needed to detect a stimulus 50% of the time.

10. Ex. Of Absolute Thresholds SenseAbsolute Threshold VisionA candle flame see at 30 mils on a dark clear night HearingThe tick of a watch under quiet conditions at 20 feet TasteOne teaspoon of sugar in two gallons of water SmellOne drop of perfume diffused into entire volume of a six room apartment TouchThe wing of a fly falling on your cheek from a distance of 1 centimeter

11. Difference Threshold The minimum difference that a person can detect between two stimuli. Also known as Just Noticeable Difference

12. Can you tell the difference?

13. Weber’s Law The idea that, to perceive a difference between two stimuli, they must differ by a constant percentage; not a constant amount.

14. Signal Detection Theory Predicts how we detect a stimulus amid other stimuli. Assumes that we do not have an absolute threshold. We detect stuff based on context: our experiences, motivations, alertness. Hearing the doorbell for the pizza guy at a loud party. Hearing your baby cry in the mall. Hearing your own cell phone in WalMart.

15. Subliminal Perception/ Stimulation The registration of sensory input without conscious awareness Does this work? Yes and No Slide studies showed some emotional reactivity (called priming a response). The effects are subtle and fleeting.

16. Sensory Adaptation Diminished sensitivity as a result of constant stimulation. Smell of a candle Feeling your clothes Bright light Hum of a fan

17. Selective Attention The focusing of conscious awareness on a particular stimulus. We are able to deliberatley focus on one stimulus while ignoring others

18. An example of selective attention is: Cocktail Part Effect: ability to listen to one voice among many.

19. http://www.youtube.com/watch?v=vJG698U2Mvo http://www.youtube.com/watch?v=vJG698U2Mvo (basketball pass study) The ability to selectively focus on one stimulus lends itself to “inattentional blindness” or the failure to notice something because you are paying attention to something else.

20. The Visual System

21. Wavelength –Determines the hue (color such as blue or green). Measured by the peak of one wave to the peak of the next. It’s all about LIGHT ENERGY. Light comes in waves, or pulses of electromagnetic energy. What we perceive, depends on the...

22. Amplitude –Dependent on the intensity of light reflected from a surface and corresponds to the brightness. Measured by the height of the wave. It’s all about LIGHT ENERGY. Light comes in waves, or pulses of electromagnetic energy. What we perceive, depends on the...

24. Vision- Spectrum of Electromagnetic Energy Insects can see shorter wavelengths Fish and reptiles can see longer wavelengths

25. Introducing...TRANSDUCTION The process of converting energy from one form to another. So, in order to “see” your brain converts electromagnetic energy into something it understands (electrochemical energy)! Transduction takes place for all of your senses.

26. The Eye

27. The cornea: clear membrane that protects the eye. The Iris – Its muscles control the size of the pupil (colored part) The Pupil – iris opening that changes size depending on the amount of light in the environment The Lens – changes shape to bring objects into focus (this process is called accommodation) Vitreous Humor—Jellylike substance between the lens and the retina The Parts of the Eye

28. More on the Eye The Retina- This is where the magic happens! the neural tissue lining the inside back surface of the eye. This is where the magic happens! The retina absorbs light, processes images and sends visual info to brain.

29. The retina contains three layers: ganglion cells, bipolar cells, and photoreceptor cells. transduced Light has to make its way through the first two layers to the receptor cells. There it is transduced into a neural impulse. Then it goes back to the ganglion and bipolar cells where it is sent to the brain.

30. Photoreceptor cells are called RODS and CONES The Fovea The Fovea – Central area of retina; greatest density of photoreceptors (mainly cones) The Optic Nerve-- The Optic Nerve-- axons of ganglion cells converging to form the optic nerve, which sends visual information to the brain via the thalamus. The Blind Spot The Blind Spot (optic disc) – Where the optic nerve leaves the eye. There are no photoreceptor cells here

32. Vision- Receptors Receptors in the Human Eye ConesRods Number Location in retina Sensitivity in dim light Color sensitive?Yes Low Center 6 million No High Periphery 120 million

33. Defects in the Lens

34. Pathways from the Eyes to the Visual Cortex 90% of axons from retina synapse here Cells here are highly specialized

35. Visual Information Processing Feature Detectors –neurons in the visual cortex of the brain that respond selectively to specific features of an object like s hape, angle, movement –These highly specialized neurons allow you to see what the edges and contours of an object and to figure out if it is hurling toward you.

36. Adaptation Dark Adaptation – the process in which the eyes become more sensitive to light in low illumination Due to chemical changes in cones and rods Light Adaptation – the process in which the eyes become less sensitive to light in high illumination

37. Trichromatic (three color) Theory –Young and Helmholtz –three different retinal color receptors Red Green Blue The colors we see are combinations of these. COLOR THEORIES

38. Opponent Process Theory Says that opposing retinal processes (red- green, yellow-blue, white-black) enable color vision. So, some cells are stimulated by red, and inhibited by green, etc.

39. Opposing process theory and afterimage effect. Stare at the center of the flag for a minute. Then shift your eyes to the white board. What do you see?

40. HEARING

41. We hear by making sense of vibrations of molecules of air. Just like vision relies on energy that is transduced into electrochemical messages, so does hearing! Wavelengths: Length of the wave determines pitch, also called frequency Amplitude determines volume Timbre: richness, purity of tone Hertz: waves per second. Humans are capable of hearing 20-20,000 Hz per second Enough about sound. Let’s talk about hearing. Word bank audition: sense of hearing

42. 1.Something in the environment vibrates and creates a sound wave. 2.The sound wave travels to the ear and is collected and channeled by the outer ear, called the pinna 3.The sound wave then moves into the auditory canal. 4.When it reaches the end of the auditory canal, the sound waves bump up against the eardrum. 5.The ear drum is a tight membrane that vibrates with these sound waves.

43. 6. The vibration moves tiny bones (hammer, anvil, and stirrup) in the middle ear. 7. These bones carry vibrations into the inner ear to a fluid-filled tube called the cochlea. 8. The fluid inside the cochlea vibrates a series of tiny hairs called cilia, which are attached to auditory nerves. 9. The movement of these cilia stimulates the nerve cells, and they send signals to the brain via the auditory nerve. 10. The auditory nerve then sends neural messages to the thalamus and on to the auditory cortex of the temporal lobe

44. http://www.youtube.com/watch?v=qgdqp- oPb1Qhttp://www.youtube.com/watch?v=qgdqp- oPb1Q 3 min http://www.youtube.com/watch?v=sv7n- hEfBfA

45. What about pitch? How do we detect high sounds from low sounds? Two theories A. Place theory says that we detect pitch because a different place on the cochlea is stimulated B. Frequency theory : says that the speed with which the nerve impulses travel up the auditory nerve matches the frequency of the tone, thus allowing us to sense its pitch. Neither one of them is a great explanation of pitch. It appears that Place Theory allows us to hear higher pitch; Frequency Theory allows us to hear low-pitched sounds.

46. FUN FACTS ABOUT HEARING 1.Fish do not have ears, but they can hear pressure changes through ridges on their body. 2.The ear’s malleus, incus and stapes (otherwise known as the hammer, anvil and stirrup) are the smallest bones in the human body. All three together could fit together on a penny. 3.The whole area of the middle ear is no bigger than an M&M. 4.The cochlea (inner ear) is about the size of a pencil eraser. 5.The ear continues to hear sounds, even while you sleep. 6.Sound travels at the speed of 1,130 feet per second, or 770 miles per hour. 7. Ears not only help you hear, but also aid in balance. 8.Sitting in front of the speakers at a rock concert can expose you to 120 decibels, which will begin to damage hearing in only 7 1/2 minutes. 9.Thirty-seven percent of children with only minimal hearing loss fail at least one grade.

47. How do you imagine that we locate where a sound is coming from? Sounds strike one ear sooner than the other which helps us determine the location of the stimulus.

48. Smell Sense of smell is called olfactory sense It is a “chemical sense” Here’s how it works: The act of sniffing moves molecules of the “thing” up the nose and into nasal cavities. Olfactory receptor cells are activated and send electrical signals There are 1,000 olfactory receptors (as opposed to only 5 for taste!) Olfactory Bulbs: located right on top of the sinus cavity on each side of the brain, directly beneath the frontal lobes. Olfactory receptors send their signals directly to the olfactory bulbs, bi-passing the thalamus

50. TASTE... Mmmmm. Sense of taste is called gustation Taste is a chemical sense Taste buds: bumps you see on your tongue are called papillae. Your taste buds actually line the walls of the papillae Each taste bud has 20 receptors. They work exactly like receptor sites on a neuron. Molecules of various substances “fit” and a signal is fired to the brain which interprets the taste

51. Humans have five basic tastes Sweet Sour They work together with texture, temperature, and heat (like spicy heat) to produce flavor. Bitter Umami Salty

52. Touch Our Tactile Sense Transduction Like your other sense organs, SKIN receives and transmits information from the outside world to the central nervous system. Transduction takes place in these sensory receptors in the skin. Skin’s basic sensations: pressure, temperature, pain There are approximately 6 receptors in the layers of skin. These each respond to different sensations, or a combination. Some respond to temperature, some to pressure, some to pain, etc.

53. The Somesthetic Senses (Soma=body, esthetic=feeling) 1. Kinesthetic: location of body parts in relation to the ground and others. Also called proprioception. To perceive and make sense of your body’s position in space, receptors in the ears. skin, joints, muscles, and tendons send signals to the brain.

55. 2. Vestibular: monitors movement and position of head, and thus your body; maintains balance The semicircular canals and the vestibular sacs of the inner ear are responsible in large part for this http://www.youtube.com/watch?v=dSHnG O9qGsE&list=PLFZXas3ALCaEgzgpW6jK wC6atD4CTTYiehttp://www.youtube.com/watch?v=dSHnG O9qGsE&list=PLFZXas3ALCaEgzgpW6jK wC6atD4CTTYie 3 minutst

56. PAIN

57. Pain Types: A. Somatic pain Can be sharp and fast (as in something is, or is about to be damaged), Can be a general ache (acts as a reminder system, keeping you from further injuring yourself (the ache of a broken bone) B. Visceral pain: pain of the organs (Pain in the stomach, intestines, or other internal organ aka: tummy ache).

58. How does pain get registered in the nervous system? Gate Control Theory First put forth in the early 60’s by Melzack and Wall This theory explains about a pain-modulating system in which a neural gate present in the spinal cord can open and close thereby altering the perception of pain. The gate control theory suggested that psychological factors play a role in the perception of pain.

59. Here’s how it would work... A sensory neuron sends a pain message: “Ouch! I twisted my ankle!” Pain message must pass through a “gate” located in the spinal cord. The gate is not a physical structure but represents the balance in neural activity of cells in the spinal cord that receive information from the body and then send the info to the brain. The activity of the gate can be closed to by non-pain signals coming into the spinal cord from the body, and by signals coming from the brain.

60. The brain then interprets the pain information and sends signals that either open the spinal gates farther, causing greater experience of pain, or close them, dampening the pain. This decision made by the brain is influenced by a number of factors... Stimulation of the pain receptor cells releases a chemical called substance P, which is released into the spinal cord and activates other neurons that send their messages. Word Bank Nociceptors: sensory receptors that detect hurtful temperatures, pressure, or chemicals

61. For example, fear, helplessness, or anxiety intensifies pain. Distraction or laughter helps minimize the pain (closes the gate). So, if you twisted your ankle, going to the fridge in the middle of the night when your parents are out of town, and you’re afraid it’s broken, the pain will be much worse than if you’re running around the neighborhood during a sleepover with all of your friends around, (possibly tp-ing) or if you are playing in a big basketball game and the score is tied at the end of the second half!

62. Up to this point, we’ve only talked about SENSATION, or the raw data that the brain gets from the sense organs. Perception is the sense your brain makes of the data! It’s your EXPERIENCE. It is your REALITY.

63. Constancies Size constancy: Objects that are closer to us produce bigger images on our retinas. (For example, if your dad is standing 100 feet from you, he would produce a smaller image on your retina. If he walks closer to you, his image on your retina will slowly increase. But you know that he is not really growing.) Size is kept constant in your mind, even though the picture on your retina changes in size.

64. Shape constancy: the tendency to perceive a shape of an object as unchanging even though it appears different from different angles. Take a look at the doors above. The one to the left looks like a rectangle, The other shapes look different on our retinas, but our mind maintains that the shape of the door remains a rectangle.

65. Brightness constancy: the t endency to perceive the color of an object the same, even though the light changes, and so it actually looks different to the retina. A tree is green in the daytime. As night comes it will look gray, or even black as the light fades. But we know that its color is always green even though it may not look so in our retina.

67. When observers approach the image fixating at the center, the upper and lower pie slices appear to be brighter and to be tinted yellowish while the right and left ones appear to be darker and to be tinted bluish. When observers move away from the image, the reversal is observed.

68. Gestalt Principles of Perception The Gestalt psychologists were interested in how we make a meaningful whole out of various parts. We have a way of integrating pieces of information into a whole that makes sense to us. The Gestalt Principle says our minds self-organize information in a manner that is orderly, regular, symmetric, and simple. This means that when we see a cluster of lines and shapes our minds attempt to organize them into a single, cohesive form, rather than a collection of individual parts.

69. 1. Figure/Ground: refers to our tendency to look at a scene and perceive it as either a “thing” or the “background.” When we have a scene that has reversible figure and ground, we continually go back and forth with what we are seeing. Gestalt Principles

70. 2. Grouping: Our tendency to make sense of a scene based on its component parts and their relationship to each other. Proximity Similarity Closure Gestalt Principles

71. 3. Continuity: The tendency to perceive things in the simplest terms possible with a continuous pattern. Although this panda is not complete, we see him as complete. Gestalt Principles

72. Depth Perception With the use of our two eyes (binocular vision), we manage to see in three dimensions. Binocular cues: We use the disparity between what image is falling on the retina in one eye compared to the image that is falling on the retina of the other eye, to quickly ascertain the depth or distance

73. However, if the thing, person, car, or house if very far away, the disparity on each retina will be minimal. In that instance, you quickly switch to monocular cues! Light and shadow help us determine distance (lighter color objects seem closer than darker colored objects)

74. Interposition: we assume that closer objects will “cut off” our vision of more distant objects.

75. atmospheric perspectiveFuzziness (If things appear fuzzy, we assume they are farther away than things that are clear). It’s actually called, “atmospheric perspective” not fuzziness).

76. Visual cliff experiments: From the time human babies are able to crawl they can judge depth This ability to perceive depth seems to be at least a partially innate characteristic in many animals, including humans

77. Sensory Interaction All of our senses influence each other to create our experience. Taste, smell, texture, temperature, and sight work together to create flavor. What is taste without smell? Do things taste different if they look different? You will be more likely to see a very dim light if it is accompanied by a sound. If you hear one thing coming from a person’s voice, and you see another, you will either trust your eyes, OR, make up a third possibility.

78. Motion Perception We perceive motion incredibly well. We judge mostly by the size of the object. Think about how cartoons work.

79. Phi Phenomenon An illusion of movement created when two or more adjacent lights blink on and off in succession.

81. Perceptual Set The tendency to perceive or notice some aspects of the available sensory data and ignore others. The perceiver has certain expectations and focuses attention on particular aspects of the sensory data.

82. There are countless real-world examples of perceptual set. BELIEVING IS SEEING

83. If I told you that one of the students in class was my daughter or son, you would likely start to perceive similarities that you hadn’t before... even if they aren’t real. Your expectations influence how you see/hear/feel things (TOP DOWN PROCESSING) Researchers deprived participants of food for several hours. When they were later shown a set of ambiguous images, those who had been food-deprived were far more likely to interpret the images as food-related objects. In one experiment, young children were found to enjoy French fries more when they were served in a McDonald's bag rather than just a plain white bag.

84. Parapsychology What you should know... What is parapsychology? What is ESP? What is psychokinesis? What is Telepathy? What is Clairvoyance? What is Precognition? Evidence for or against any of it???Evidence for or against any of it???