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Sensation and perception
- 2. SENSE ORGANS -contains Receptors ( highly sensitive cells) -responsible for translating stimulations to neural impulse Language of the nervous system
- 3. Sufficient stimulation of the sense organs to produce neural impulse to be sent to the nervous system Sensatio n •occurs when energy in the external environment or the body stimulates receptors in the sense organs.
- 4. Sensation
- 5. Perception •Refers to the way in which sensory inputs from the sense organs are organized, analyzed, and interpreted in a meaningful way. Refers to the meaningful interpretation of Sensation
- 6. PERCEPTION
- 7. “I have perfect vision but the problem is with my perception. –Heather Sellers “In college, on a date at the Spaghetti Station, I returned from the bathroom and plunked myself down in the wrong booth, facing the wrong man. I remained unaware he was not my date. I can’t distinguish actors in movies and on TV. I do not recognize myself in photos or video. I can’t recognize my stepsons in the soccer pick-up line; I failed to determine which husband was mine at a party, in the mall, at the market” •She cannot recognize faces-prosopagnosia (face blindness) This curious mix of “perfect” vision and face blindness illustrates the distinction between sensation and perception. Case of Sensation vs perception
- 8. CHARACTERISTICS OF SENSORY RECEPTORS 1. Selectivity 2. Adaptation •Sensory receptors- detect and respond to one type of sensory stimuli- light, smell, etc. •Transduction-the sensory receptors convert the sensory stimulation into neural impulses. •Allows us to adjust or adapt to the unchanging stimulation
- 9. SENSORY THRESHOLDS 1. Absolute Threshold •The intensity in which we can discriminate the presence or absence of stimulation •Weakest amount of a stimulus that can be distinguished from no stimulus at all
- 10. 2. Absolute Threshold •Weakest amount of a stimulus that can be distinguished from no stimulus at all • Detected 50% of the time
- 11. 2. Difference Threshold (Just Noticeable Difference) •Minimum amount by which stimulus intensity must be changed in order to produce a noticeable difference in sensation.
- 12. SENSE OF SIGHT
- 13. Sense of Sight •Seeing begins when light waves enter the eyes. •Spectrum of electromagnetic energy •Vary in wavelength •Human eyes can perceive only a very thin band of electromagnetic waves, known as the visible spectrum (400 – 700nanometers) •Within visible light, color is determined by wavelength
- 15. The Eye •Light enters through a narrow opening • Cornea – transparent eye cover • Iris – muscle; colored part of the eye • Pupil – opening in the iris •Sensitive to light and emotion
- 16. Structure The Eye (Divided into three layers) 1.Sclerotic Coat Sclera- white part of the eye Cornea- top transparent coat located in front of the eyes 1.Choroid 2.Retina (contains photoreceptors) Rods- functions in dim light (nocturnal vision), detects movement, cannot detect color, responsible for peripheral vision Cones- functions best in bright light, provide sharp vision, allows us to see in different colors 3 types of Cones: red, blue and green sensitive cones
- 17. TWO KINDS OF ADAPTATION •Dark adaptation -Process of adjusting to lower lighting -Decrease sensitivity to light after a person enters a dark room •Light adaptation - A decrease sensitivity in darkness after a person walks out dark room
- 18. COMMON VISUAL PROBLEMS 1. MYOPIA (Nearsightedness) -occurs when light is focused in front of the retina 1. HYPEROPIA ( Far sightedness) - Occurs when light is focused behind the retina 1. ASTIGMATISM -Uneven curvature of the cornea and the light is unevenly focused in the retina -Vision appears blurred or distorted
- 20. Theories of Color •Trichromatic Theory •Three types of cones •Sensitive to red, green, or blue •Opponent-Process Theory • Three types of color receptors •Red-green, blue-yellow, and light-dark
- 21. Trichromat Normal color vision Color Blindness •Monochromat -Totally color blind (black and white vision) •Dichromat -Partial color blindness -Difficulty in distinguishing between two colors (red & green, or blue &yellow)
- 22. Plates from a Test for Color Blindness
- 23. Red Green Violet Yellow Green Blue Orange White Black Black Black Yellow Red White Green
- 24. Sense of Hearing and Balance
- 25. Sense of Hearing •Hearing begins when sound waves enter the ear •Human ear is sensitive to a particular range of sound waves • Measured in terms of cycles per second, or Hertz (Hz) •Human ear is sensitive to sound waves with frequencies of 20 - 20,000 cycles per second Hearing range decreases as we age, by the age of 70 many people have trouble hearing sounds above 6,000 Hz
- 26. Properties of Sound •Amplitude • Pertains to loudness of the sound • Expressed in decibels (dB) •Frequency • Pertains to pitch of the sound • # of cycles per second • Expressed in hertz (Hz) • Pitch of women’s voice is higher than men’s •Timbre • Pertains to distinct quality of sound. • Distinguishes between two tones that have the same loudness and frequency but still sounds different
- 27. Sound Waves of Various Frequencies and Amplitudes
- 29. Parts of the Ear 1. Outer Ear •Composed of the Pinna or the external ear, auditory canal and the eardrum •Funnels sound waves to the eardrum 2. Middle Ear •Tiniest bones in the middle ear: Ossicles (hammer, anvil and stirrup) •Acts as an amplifier •Oval window – Round window-balances the pressure
- 30. Parts of the Ear 3. Inner Ear •Composed of two organs: •hearing -Cochlea •Contains hair cells •Tubes inside the cochlea contains fluid •Basilar membrane (center for auditory transduction) •Sense of Balance -Vestibular apparatus -it allows us to be aware of the relative position of our head with regard to space
- 31. The Human Ear
- 32. Deafness •Conductive deafness • Damage to middle ear • Hearing aids can help •Sensorineural deafness • Damage to inner ear or auditory nerve • Cochlear implants may help with damage to inner ear, but not auditory nerve
- 33. The Chemical Senses: Smell and Taste
- 34. Sense of Smell •We smell when the molecules in the air we breathe enter our nostrils •Odors (molecules in the air) trigger receptor neurons in olfactory membrane •Sensory information about odors is sent to the brain through the olfactory nerve •Odor contributes to flavor of foods
- 37. Sense of Taste •Taste is sensed through taste cells •Receptor neurons on taste buds •Four primary taste qualities •Sweet, sour, salty and bitter •Umami (fifth basic taste) – savory •Flavor of food depends on odor, texture, temperature and taste •Individuals have taste sensitivities
- 40. Physiological Basis of Taste: Gustatory Sensation -The top of your tongue is covered with a layer of bumps called papillae - Papillae contains the taste buds -Flavoring chemicals in food dissolve in the saliva -The saliva carries the flavor of the food and enters the gustatory pore - When the saliva comes into contact with the gustatory hairs, chemical reactions are translated to neural impulse. -Messages are sent to the brain to give us the taste of the food
- 42. Sense of Touch
- 43. Touch and Pressure •Our ability to experience touch, pain, pressure, warm sensation and cold sensation is due to the excitation of numerous receptors found in the skin •Sensory receptors in skin fire when skin surface is touched
- 44. Receptors of touch •MECHANORECEPTORS •Respond to mechanical stimulation such as pressure, stretching of the skin and vibration •4 types •Merkel •Meissner disks •Ruffini cylinders •Pacinian corpuscles
- 46. •NOCICEPTORS •Pain receptors are found among the free nerve endings located both near the surface of the skin (detect extreme temperatures) and below the skin’s surface ( detects sharp and punctuate sensation)
- 47. Gate Theory of Pain •Nervous system can only process a limited amount of stimulation •Rubbing the pained area competes for neural attention •Closes the “gate” on pain messages to the brain
- 48. trivia
- 52. 1. Visual Perception •Process used to organize sensory impressions caused by the light that strikes our eyes •Sensation is a mechanical process •Perception is an active process • Involves experience, expectations and motivations
- 53. 1. Visual Perception •Process used to organize sensory impressions caused by the light that strikes our eyes •Sensation is a mechanical process •Perception is an active process • Involves experience, expectations and motivations
- 54. Visual Perception •Process used to organize sensory impressions caused by the light that strikes our eyes •Sensation is a mechanical process •Perception is an active process • Involves experience, expectations and motivations
- 55. Perceptual Organization •Figure – Ground Perception • Ambiguous, unstable figures, we shift back & forth
- 56. Gestalt Rules for Perceptual Organization
- 57. Gestalt Rules for Perceptual Organization • Common Fate • Elements moving together are grouped together (runners) • Closure • Fit bits of information into familiar patterns; • Perception of a complete figure, even when there are gaps in sensory information • Proximity • Nearness of objects • Similarity • Similarity of objects • Continuity • Series of points having unity
- 58. Perception of Motion (mini class discussion) •Visual perception of motion is based on change of position relative to other objects •Illusions of movement • Stroboscopic motion (class discussion, how do we know that a train moves?)
- 59. Depth Perception • Monocular Cues • Perspective • Clearness • Overlapping • Shadows • Texture gradient • Motion parallax • Binocular Cues • Retinal disparity • Convergence
- 60. Perceptual Constancies •Acquired through experience; creates stability • Size Constancy (video) • Color Constancy • Brightness Constancy • Shape Constancy
- 62. Visual Illusions •Hering-Hemlholtz Illusion • Perceive drawing as three-dimensional •Müller-Lyer Illusion • Interpret length of lines based on experience
- 63. ESP: Is There Perception Without Sensation?
- 64. Extrasensory Perception - ESP •Perception through means other than sensory organs • Precognition • Psychokinesis • Telepathy • Clairvoyance
- 65. Existence of ESP •Ganzfield Procedure • Method for studying the existence of ESP •No reliable evidence for existence of ESP
- 66. Beyond the Book
- 67. Video Connections: The Ames Room •Based on what you learn from the video about the Ames Room, how do visual artists use illusions to create a sense of depth in two-dimensional paintings?
- 69. Video Connections: The Ames Room •Have you ever been surprised at how large the moon looks on the horizon, “resting” atop buildings or trees in the distance? How do you explain why it looks larger under these circumstances than when it is high in the sky? •Can we rely on our past experience of rooms to make sense of the Ames Room? Why or why not?
- 70. Virtual Reality •Perception of events that are fed directly into the sense via electronic technology •Computer generated images used to overcome phobias •Cybersex
Notes de l'éditeur
- Truth or Fiction? People have five senses. FALSE People have many more than five senses. Touch is just one of your “skin senses” which also include pressure, warmth, cold, and pain. There are also senses that alert you to your own body position without your having to watch every step you take.
- Truth or Fiction? If we could see waves of light with slightly longer wavelengths, warm-blooded animals would glow in the dark. TRUE If you could see light with slightly longer wavelengths, you would see infrared light waves. Since heat generates infrared light, warm-blooded people, including other people would glow in the dark. Vision – a candle flame viewed from about 30 miles on a clear night Hearing – a watch ticking from about 20 feet away in a quiet room Taste – 1 teaspoon of sugar dissolved in 2 gallons of water Smell – about one drop of perfume diffused though a small house Touch – the pressure of the wing of a fly falling on a check about a distance of about .4 inch
- Truth or Fiction? If we could see waves of light with slightly longer wavelengths, warm-blooded animals would glow in the dark. TRUE If you could see light with slightly longer wavelengths, you would see infrared light waves. Since heat generates infrared light, warm-blooded people, including other people would glow in the dark. Vision – a candle flame viewed from about 30 miles on a clear night Hearing – a watch ticking from about 20 feet away in a quiet room Taste – 1 teaspoon of sugar dissolved in 2 gallons of water Smell – about one drop of perfume diffused though a small house Touch – the pressure of the wing of a fly falling on a check about a distance of about .4 inch
- Weber’s constant Light – 2% of intensity Weight – 2% of weight Sound – one-third of 1% change in pitch (frequency) Taste – 20% difference in saltiness
- The human eye is sensitive only to a particular range of wavelength called visible spectrum
- The longest wavelength we can see is red and the shortest is violet. We cannot see infrared or ultraviolet rays. Figure 4.1 The Visible Spectrum. By passing a source of white light, such as sunlight, through a prism, we break it down into the colors of the visible spectrum. The visible spectrum is just a narrow segment of the electromagnetic spectrum. The electromagnetic spectrum also includes radio waves, microwaves, X rays, cosmic rays, and many others. Different forms of electromagnetic energy have wave-lengths which vary from a few trillonths of a meter to thousands of miles. Visible light varies in wave-length from about 400 to 700 billionths of a meter. (A meter = 39.37 inches.)
- Light enters the cornea, light bent to the opening of the eyes called the PUPIL. The iris regulates the amount of light that enters the eye. The pupil dilates when dim and constricts when its bright. Regulated by the ANS from the pupil it will pass through the lens then through the Retina where the photoreceptors are. When converted by the rods and cones, the neural impulse is transmitted to the brain through the optic nerve to the occipital region where it is analyzed. Only then we can interpret it as an image. all of this happens in a fraction of second.
- Figure 4.6 Place a sheet of white paper beneath the book, and stare at the black dot in the center of the flag for at least 30 seconds. Then remove the book. The afterimage on the paper beneath will look familiar. In the classroom, have students stare at the black dot in the center of the flag for at least 30 seconds. Then look at a white wall and the afterimage will appear.
- Figure 4.7 Plates from a Test for Color Blindness. Can you see the numbers in these plates from a test for color blindness? A person with red-green color blindness would not be able to see the 6, and a person with blue-yellow color blindness would probably not discern the 12. (Caution. These reproductions cannot be used for actual testing of color blindness.)
- Hearing range decreases as we age, by the age of 70 many people have trouble hearing sounds above 6,000 Hz
- PITCH- the more frequent the vibration, the higher the pitch of the sound sound waves are closer to each other One cycle per second = 1 Hz Pitch of women’s voice is higher than men’s Women’s vocal cords are usually shorter Vocal cords vibrate at a greater frequency
- Figure 4.14 Sound Waves of Various Frequencies and Amplitudes. Which sounds have the highest pitch? Which are loudest?
- Figure 4.15 Decibel Ratings of Familiar Sounds. Zero dB is the threshold of hearing. You may suffer hearing loss if you incur prolonged exposure to sounds of 85 to 90 dB.
- Hearing begins when the external ear collects sound waves and hits the eardrum Eardrum vibrates when it is hit Stirrup- oval window- vibration passes from the bones of the middle ear to the inner ear
- Malfunctions= dizziness/ loss of balance Receptors: hair cells found in this apparatus
- Figure 4.16 The Human Ear. The outer ear funnels sound to the eardrum. Inside the eardrum, vibrations of the hammer, anvil, and stirrup transmit sound to the inner ear. Vibrations in the cochlea transmit the sound to the auditory nerve by way of basilar membrane and the organ of Corti.
- We smell when the molecules in the air we breathe enter our nostrils
- As we inhale, the air along with the chemical substances in the air goes inside our nasal cavity and stimulates the hair like cells that project from our olfactory bulb. HAIR Cells are responsible for converting chem. Reactions to neural impulses that are sent to the brain via olfactory nerve. Only when the signals from the nose are analyzed in the cortex can we distinguish the odor of what we smell
- Sense of smell is the first to mature because it is relevant for survival We seem to know by instinct that foul smelling substances are harmful to the body That is why we cover our nose when we smell something bad. Covering our nose is one of the ways by which we protect ourselves from infection and contamination Our sense of smell adapt to quickly
- The top of your tongue is covered with a layer of bumps called papillae Papillae help grip food and move it around while you chew. They contain your taste buds, so you can taste everything.
- There are neurons in the spinal cord that serves as gate to pain Pain generated by small nerve fibers are allowed to pass the gate Signal carried by large nerve fibers are prevented from passing the gate It is theorized that pain is felt only when the fiber that carries the pain signal enters the pain gate and gets to the brain
- Example of Figure and Ground are available in the textbook, Figure 4.9.
- Figure 4.10 Some Gestalt Laws of Perceptual Organization. These drawings illustrate the Gestalt laws of proximity, similarity, continuity, and closure.
- Examples of closure can be found in text Figure 4.8.
- Refer to Figure 4.11 for a demonstration of overlapping and shadowing
- Size constancy. See a video demonstration of size constancy.
- Refer to Figure 4.13 in the text for an example of both the Hering-Helmholtz and the Müller Lyer Illusion. For some on-line examples of many of the visual phenomena, see Project Lite, an atlas of visual phenomena, created by Kenneth Brecher and Scott Gorlin and funded by an NSF Grant at http://lite.bu.edu/vision/applets/lite/lite/lite.html
- Precognition - Able to perceive future events in advance Psychokinesis - Mentally manipulating or moving objects Telepathy - Direct transmission of thought or ideas from one person to another Clairvoyance - Perception of objects that do not stimulate sensory organs
- Truth or Fiction? Some people can read other people’s minds. FALSE There is no adequate scientific evidence that people can read other people’s minds.
- Learning Objectives of Video Connections: The Ames Room. Explain the source of confusion in the Ames room. Understand how our perception can sometimes be “tricked.”
- Learning Objectives of Video Connections: The Ames Room. Explain the source of confusion in the Ames room. Understand how our perception can sometimes be “tricked.”