Psychology Chapter 8

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Psychology Chapter 8

  1. 1. Chapter 8 Sensation and Perception
  2. 2. Section 1 Sensation
  3. 3. What is Sensation? <ul><li>Sensation- what occurs when a stimulus activates a receptor. </li></ul><ul><li>Perception- the organization of sensory information into meaningful experiences </li></ul><ul><li>Pyschophysics- the study of the relationships between sensory experiences and the physical stimuli that cause them </li></ul>
  4. 4. Threshold <ul><li>Absolute threshold- is the weakest amount of a stimulus that a person can detect half the time </li></ul><ul><li>Difference threshold- the smallest change in a physical stimulus that can be detected half the time </li></ul>
  5. 5. Sensory Differences and Ratios <ul><li>Just noticeable difference (JND)- the smallest increase or decrease in the intensity of a stimulus that a person is able to detect half of the time. </li></ul><ul><li>Weber’s law: the principle that for any change in a stimulus to be detected, a constant proportion of that stimulus must be added or subtracted. </li></ul>
  6. 6. Sensory Differences and Ratios <ul><li>Some senses produce huge increases in sensation in response to a small amount of energy </li></ul>
  7. 7. Sensory Adaptation <ul><li>Senses are tuned to change when exposed to stimuli </li></ul><ul><li>People have the ability to adapt to stimulation in the environment </li></ul><ul><ul><li>Adjusting to a dark movie theatre </li></ul></ul><ul><li>Allows us to notice differences in sensations and react to the challenges of different or changing stimuli </li></ul>
  8. 8. Signal-Detection Theory <ul><li>Is the study of people’s tendencies to make correct judgments in detecting the presence of a stimuli. </li></ul><ul><li>Detection thresholds- involve recognizing some stimulus against a background of competing stimuli. </li></ul>
  9. 9. Two types of processing stimuli or signals <ul><li>Preattentive process- method for extracting information automatically and simultaneously when presented with stimuli. </li></ul><ul><li>Attentive process- is a procedure that considers only one part of the stimuli presented at a time. </li></ul>
  10. 10. Section 2 The Senses
  11. 11. The Senses <ul><li>Vision </li></ul><ul><li>Hearing </li></ul><ul><li>Taste </li></ul><ul><li>Smell </li></ul><ul><li>Touch </li></ul><ul><li>Skin senses </li></ul><ul><ul><li>Vestibular </li></ul></ul><ul><ul><li>Kinesthetic </li></ul></ul>
  12. 12. Vision <ul><li>Most studied of all senses </li></ul><ul><li>Pupil- the opening in the iris that regulates the amount of light entering the eye </li></ul><ul><li>Lens- a flexible, elastic, transparent structure in the eye that changes its shape to focus light on the retina </li></ul>
  13. 13. Vision <ul><li>Retina- the innermost coating of the back of the eye, containing the light-sensitive receptor cells </li></ul><ul><ul><li>Rods & cones are responsible for changing light energy into neuronal impulses </li></ul></ul><ul><li>Optic nerve- the nerve that carries impulses from the retina to the brain </li></ul>
  14. 14. Light <ul><li>Is a form of electromagnetic radiation </li></ul><ul><li>Electromagnetic spectrum is made up of: </li></ul><ul><ul><li>Radio waves </li></ul></ul><ul><ul><li>Microwaves </li></ul></ul><ul><ul><li>Infrared radiation </li></ul></ul><ul><ul><li>Ultraviolet rays </li></ul></ul><ul><ul><li>X-rays </li></ul></ul><ul><ul><li>Gamma rays </li></ul></ul>
  15. 15. Light <ul><li>Visible light only makes up a small portion of the electromagnetic spectrum </li></ul><ul><li>Passing sunlight through a spectrum breaks the light into a rainbow of colors, each color having a different wavelength </li></ul>
  16. 16. Color Deficiency <ul><li>If a person’s cones don’t function correctly, the person is color-deficient </li></ul><ul><li>Fewer people have trouble between red and green than yellow and blue </li></ul><ul><li>8% of American men and 1% of American women are color blind/color deficient </li></ul>
  17. 17. Binocular Fusion <ul><li>Is the process of combining the images received from the two eyes into a single, fused image </li></ul><ul><li>Retinal disparity- is the differences between the images stimulating each eye </li></ul><ul><li>Depth perception </li></ul><ul><ul><li>Large retinal disparity means object is nearby </li></ul></ul><ul><ul><li>Small retinal disparity means object is distant </li></ul></ul>
  18. 18. Nearsightedness and Farsightedness <ul><li>Long eyeball usually means you are nearsighted </li></ul><ul><ul><li>You can see objects close to you, but objects in the distance are blurry </li></ul></ul><ul><li>Short eyeball usually means you are farsighted </li></ul><ul><ul><li>You can see distant objects clear, but up-close objects are blurry </li></ul></ul>
  19. 19. Hearing <ul><li>Depends on the vibration of sound waves in the air </li></ul><ul><li>Auditory nerve- is the nerve that carries impulses from the inner ear to the brain, resulting in the perception of sound </li></ul><ul><li>Loudness- determined by amplitude </li></ul><ul><ul><li>Higher the amplitude, the louder the sound </li></ul></ul><ul><ul><li>Decibels- sound-pressure energy </li></ul></ul>
  20. 20. Hearing <ul><li>Pitch- based on sound wave frequency </li></ul><ul><ul><li>Low frequency- deep bass sounds </li></ul></ul><ul><ul><li>High frequency- shrill squeaks </li></ul></ul><ul><li>You can find the source of a sound when both ears work together </li></ul>
  21. 21. The Pathway of Sound <ul><li>Outer ear </li></ul><ul><ul><li>Receives sound waves and directs sounds through the auditory canal </li></ul></ul><ul><li>Middle ear- air-filled cavity </li></ul><ul><ul><li>3 bones (hammer, anvil, and stirrup) are linked to the ear drum on one end and the cochlea </li></ul></ul>
  22. 22. The Pathway of Sound <ul><li>Inner ear </li></ul><ul><ul><li>Cochlea makes up the inner ear </li></ul></ul><ul><ul><li>Bony tube that contains fluids and neurons </li></ul></ul><ul><ul><li>Pressure makes the liquid inside move </li></ul></ul><ul><ul><li>Tiny hairs in the cochlea pick up motion which are attached to sensory cells </li></ul></ul><ul><ul><li>These cells turn the sound vibrations into neuronal impulses, which are sent to the brain </li></ul></ul>
  23. 23. Deafness <ul><li>Conduction deafness- occurs when something hinders motion through the outer or middle ear or when bones of the middle ear become rigid and cannot carry sounds inward </li></ul><ul><ul><li>Usually helped with a hearing aid </li></ul></ul>
  24. 24. Deafness <ul><li>Sensorineural- occurs from damage to the cochlea, hair cells, or auditory neurons </li></ul><ul><ul><li>Can be helped by a cochlear implant </li></ul></ul><ul><ul><li>Cochlear implant- is a miniature electronic device surgically implanted </li></ul></ul>
  25. 25. Balance <ul><li>Vestibular system- three semicircular canals that provide the sense of balance, located in the inner ear and connected to the brain by a nerve </li></ul><ul><li>Over-stimulation of the vestibular sense will make you dizzy and possibly motion sick </li></ul>
  26. 26. Smell and Taste <ul><li>Known as chemical senses because their receptors are sensitive to chemical molecules </li></ul><ul><li>Olfactory nerve- the nerve that carries smell impulses from the nose to the brain </li></ul><ul><li>Liquid chemicals must stimulate receptors in the taste buds for you to taste something </li></ul>
  27. 27. The Skin Senses <ul><li>Skin provides the brain with four kinds of information about the environment: </li></ul><ul><ul><li>Pressure </li></ul></ul><ul><ul><li>Warmth </li></ul></ul><ul><ul><li>Cold </li></ul></ul><ul><ul><li>Pain </li></ul></ul><ul><li>Pressure varies from place to place on the skin </li></ul>
  28. 28. The Skin Senses <ul><li>Pressure sensations can serve as protection </li></ul><ul><li>Many things that can produce pain: </li></ul><ul><ul><li>Scratches, punctures, heat, and cold </li></ul></ul><ul><li>Pain makes it possible for you to prevent damage to your body </li></ul>
  29. 29. Perceptions of Pain <ul><li>Two types of pain sensation </li></ul><ul><ul><li>sharp- localized pain you may feel immediately after an injury </li></ul></ul><ul><ul><li>Dull- generalized pain you may feel later </li></ul></ul><ul><li>Gate control theory of pain- we can lessen some pains by shifting our attention away from the pain impulses or by sending other signals to complete with the pain signals </li></ul>
  30. 30. The Body Senses <ul><li>Kinesthesis- The sense of movement and body position </li></ul><ul><ul><li>Comes from receptors in and near the muscles, tendons, and joints </li></ul></ul><ul><ul><li>Without kinesthetic sensations your movements would be jerky and uncoordinated </li></ul></ul>
  31. 31. Section 3 Perception
  32. 32. Perception <ul><li>Is when the brain receives information from the senses and organizes and interprets it into meaningful experiences </li></ul><ul><li>Goes beyond our reflexive behavior </li></ul><ul><li>Allows us to confront changes in our environment </li></ul>
  33. 33. Principles of Perceptual Organization <ul><li>Gestalt- is the experience that comes from organizing bits and pieces of information into meaningful wholes </li></ul><ul><li>Psychologists have tried to identify principles the brain uses to construct perceptions </li></ul><ul><ul><li>Proximity, continuity, similarity, simplicity, closure </li></ul></ul>
  34. 34. Figure-ground Perception <ul><li>Is the ability to discriminate properly between a figure and its background. </li></ul><ul><li>Two dimensional objects are heard to tell the figure from the ground </li></ul><ul><li>These are important in hearing and vision </li></ul><ul><li>In music: </li></ul><ul><ul><li>The melody becomes the figure, the rest of the music becomes the background </li></ul></ul>
  35. 35. Perceptual Inference <ul><li>Is the phenomena of filling in the gaps in what our senses tell us is known </li></ul><ul><li>Usually automatic and unconscious </li></ul><ul><li>Differs by our experiences </li></ul>
  36. 36. Learning to Perceive <ul><li>Something people learn to do </li></ul><ul><li>Active involvement in the environment is important for accurate perception </li></ul><ul><li>Is influenced by our needs, beliefs, and expectations </li></ul><ul><li>Perceptual set- prepares you to see what you want to see </li></ul>
  37. 37. Subliminal Perception <ul><li>Subliminal messages: brief auditory or visual messages that are presented below the absolute threshold </li></ul><ul><li>Subliminal perception: the ability to notice stimuli that affect only the unconscious mind </li></ul><ul><li>The Hidden Persuaders by Vance Packard believed advertisers were using subliminal advertising in 1957. </li></ul>
  38. 38. Depth Perception <ul><li>Being able to recognize distances and 3-D </li></ul><ul><li>Is being developed as an infant </li></ul><ul><li>Study: </li></ul><ul><ul><li>Babies would not crawl of the edge of a table, they realized the difference; so they believe depth perception is developing as an infant </li></ul></ul>
  39. 39. Monocular Depth Cues <ul><li>Cues that can be used with a single eye </li></ul><ul><ul><li>Size of an object </li></ul></ul><ul><ul><li>Relative height </li></ul></ul><ul><ul><li>Interposition- overlapping of images </li></ul></ul><ul><ul><li>Light and shadows </li></ul></ul><ul><ul><li>Texture-density gradient </li></ul></ul><ul><li>Motion parallax- is the apparent movement of stationary objects relative to one another that occurs when the observer changes postion </li></ul>
  40. 40. Monocular Cues <ul><li>Linear perspective- parallel lines converge when stretched into the distance </li></ul><ul><li>Relative motion </li></ul><ul><ul><li>Objects nearby seem to be moving in the opposite direction when focusing on a distant object </li></ul></ul>
  41. 41. Binocular Depth Cues <ul><li>Depend on the existence or movement of both eyes </li></ul><ul><li>Retinal disparity- each eye occupies a different position, each eye receives a different image </li></ul>
  42. 42. Constancy <ul><li>The tendency to perceive certain objects in the same way regardless of changing angle, distance, or lighting </li></ul>
  43. 43. Illusions <ul><li>Perceptions that misrepresent physical stimuli </li></ul><ul><li>Perceptual cues are distorted so our brains cannot interpret: </li></ul><ul><ul><li>Space, size, and depth cues </li></ul></ul>
  44. 44. Extrasensory Perception <ul><li>Is an ability to gain information by some means other than the ordinary senses </li></ul><ul><li>Four types of ESP </li></ul><ul><ul><li>Clairvoyance- is perceiving objects or information without sensory input </li></ul></ul><ul><ul><li>Telepathy- involves reading someone else’s mind or transferring one’s thoughts </li></ul></ul><ul><ul><li>Psychokinesis- moving objects through purely mental effort </li></ul></ul><ul><ul><li>Precognition is the ability to foretell event </li></ul></ul>
  45. 45. Extrasensory Perception <ul><li>Intense personal experience that can be scientifically validated </li></ul><ul><li>J.B. Rhine- parapsychologist that has been studying ESP since the early 1900s </li></ul>
  46. 46. Source: <ul><li>Kasschau, Richard, A. Understanding Psychology . McGraw-Hill, Glencoe, New York, New York, 2008. </li></ul>

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