Ce diaporama a bien été signalé.
Le téléchargement de votre SlideShare est en cours. ×
Chargement dans…3

Consultez-les par la suite

1 sur 35 Publicité

Plus De Contenu Connexe

Diaporamas pour vous (20)


Plus récents (20)


  1. 1. Chapter 5 Sensation
  2. 2. Sensation <ul><li>Sensation </li></ul><ul><ul><li>a process by which our sensory receptors and nervous system receive and represent stimulus energy </li></ul></ul><ul><li>Perception </li></ul><ul><ul><li>a process of organizing and interpreting sensory information, enabling us to recognize meaningful objects and events </li></ul></ul>
  3. 3. Sensation <ul><li>Bottom-Up Processing </li></ul><ul><ul><li>analysis that begins with the sense receptors and works up to the brain’s integration of sensory information </li></ul></ul><ul><li>Top-Down Processing </li></ul><ul><ul><li>information processing guided by higher-level mental processes </li></ul></ul><ul><ul><li>as when we construct perceptions drawing on our experience and expectations </li></ul></ul>
  4. 4. Sensation- Basic Principles <ul><li>Psychophysics </li></ul><ul><ul><li>study of the relationship between physical characteristics of stimuli and our psychological experience of them </li></ul></ul><ul><ul><li>Light- brightness </li></ul></ul><ul><ul><li>Sound- volume </li></ul></ul><ul><ul><li>Pressure- weight </li></ul></ul><ul><ul><li>Taste- sweetness </li></ul></ul>
  5. 5. Sensation- Thresholds <ul><li>Absolute Threshold </li></ul><ul><ul><li>minimum stimulation needed to detect a particular stimulus </li></ul></ul><ul><ul><li>usually defined as the stimulus needed for detection 50% of the time </li></ul></ul><ul><li>Difference Threshold </li></ul><ul><ul><li>minimum difference between two stimuli that a subject can detect 50% of the time </li></ul></ul><ul><ul><li>just noticeable difference (JND) </li></ul></ul><ul><ul><li>increases with magnitude </li></ul></ul>
  6. 6. Sensation- Thresholds <ul><li>Signal Detection Theory </li></ul><ul><ul><li>predicts how and when we detect the presence of a faint stimulus (signal) amid background stimulation (noise) </li></ul></ul><ul><ul><li>assumes that there is no single absolute threshold </li></ul></ul><ul><ul><li>detection depends partly on person’s </li></ul></ul><ul><ul><ul><li>experience </li></ul></ul></ul><ul><ul><ul><li>expectations </li></ul></ul></ul><ul><ul><ul><li>motivation </li></ul></ul></ul><ul><ul><ul><li>level of fatigue </li></ul></ul></ul>
  7. 7. Sensation- Thresholds <ul><li>Weber’s Law- to perceive a difference between two stimuli, they must differ by a constant proportion </li></ul><ul><ul><li>light intensity- 8% </li></ul></ul><ul><ul><li>weight- 2% </li></ul></ul><ul><ul><li>tone frequency- 0.3% </li></ul></ul><ul><li>Sensory adaptation- diminished sensitivity with constant stimulation </li></ul>
  8. 8. Vision <ul><li>Transduction- conversion of one form of energy to another </li></ul><ul><li>Wavelength- the distance from the peak of one wave to the peak of the next </li></ul><ul><li>Hue- dimension of color determined by wavelength of light </li></ul><ul><li>Intensity- amount of energy in a wave determined by amplitude </li></ul><ul><ul><li>brightness </li></ul></ul><ul><ul><li>loudness </li></ul></ul>
  9. 9. Vision- Spectrum of Electromagnetic Energy
  10. 10. Vision <ul><li>Pupil- adjustable opening in the center of the eye </li></ul><ul><li>Iris- a ring of muscle the forms the colored portion of the eye around the pupil and controls the size of the pupil opening </li></ul><ul><li>Lens- transparent structure behind pupil that changes shape to focus images on the retina </li></ul>
  11. 11. Vision
  12. 12. Vision <ul><li>Accommodation </li></ul><ul><ul><li>change in shape of lens </li></ul></ul><ul><ul><li>focus near objects </li></ul></ul><ul><li>Retina </li></ul><ul><ul><li>inner surface of eye </li></ul></ul><ul><ul><li>light sensitive </li></ul></ul><ul><ul><li>contains rods and cones </li></ul></ul><ul><ul><li>layers of neurons </li></ul></ul><ul><ul><li>beginning of visual information processing </li></ul></ul>
  13. 13. Vision <ul><li>Acuity- the sharpness of vision </li></ul><ul><li>Nearsightedness </li></ul><ul><ul><li>nearby objects seen more clearly </li></ul></ul><ul><ul><li>lens focuses image of distant objects in front of retina </li></ul></ul><ul><li>Farsightedness </li></ul><ul><ul><li>faraway objects seen more clearly </li></ul></ul><ul><ul><li>lens focuses near objects behind retina </li></ul></ul>
  14. 14. Retina’s Reaction to Light- Receptors <ul><li>Cones </li></ul><ul><ul><li>near center of retina (fovea) </li></ul></ul><ul><ul><li>fine detail and color vision </li></ul></ul><ul><ul><li>daylight or well-lit conditions </li></ul></ul><ul><li>Rods </li></ul><ul><ul><li>peripheral retina </li></ul></ul><ul><ul><li>detect black, white and gray </li></ul></ul><ul><ul><li>twilight or low light </li></ul></ul>
  15. 15. Retina’s Reaction to Light <ul><li>Optic nerve- nerve that carries neural impulses from the eye to the brain </li></ul><ul><li>Blind Spot- point at which the optic nerve leaves the eye, creating a “blind spot” because there are no receptor cells located there </li></ul><ul><li>Fovea- central point in the retina, around which the eye’s cones cluster </li></ul>
  16. 16. Vision- Receptors Receptors in the Human Eye Cones Rods Number Location in retina Sensitivity in dim light Color sensitive? Yes Low Center 6 million No High Periphery 120 million
  17. 17. Pathways from the Eyes to the Visual Cortex
  18. 18. Visual Information Processing <ul><li>Feature Detectors </li></ul><ul><ul><li>neurons in the visual cortex respond to specific features </li></ul></ul><ul><ul><li>shape </li></ul></ul><ul><ul><li>angle </li></ul></ul><ul><ul><li>movement </li></ul></ul>Stimulus Cell’s responses
  19. 19. How the Brain Perceives
  20. 20. Illusory Contours
  21. 21. Visual Information Processing <ul><li>Parallel Processing </li></ul><ul><ul><li>simultaneous processing of several dimensions through multiple pathways </li></ul></ul><ul><ul><li>color </li></ul></ul><ul><ul><li>motion </li></ul></ul><ul><ul><li>form </li></ul></ul><ul><ul><li>depth </li></ul></ul>
  22. 22. Visual Information Processing <ul><li>Trichromatic (three color) Theory </li></ul><ul><ul><li>Young and Helmholtz </li></ul></ul><ul><ul><li>three different retinal color receptors </li></ul></ul><ul><ul><ul><li>red </li></ul></ul></ul><ul><ul><ul><li>green </li></ul></ul></ul><ul><ul><ul><li>blue </li></ul></ul></ul>
  23. 23. Color-Deficient Vision <ul><li>People who suffer red-green blindness have trouble perceiving the number within the design </li></ul>
  24. 24. Visual Information Processing <ul><li>Opponent-Process Theory- opposing retinal processes enable color vision </li></ul><ul><li>“ ON” “OFF” </li></ul><ul><li>red green </li></ul><ul><li>green red </li></ul><ul><li>blue yellow </li></ul><ul><li>yellow blue </li></ul><ul><li>black white </li></ul><ul><li>white black </li></ul>
  25. 25. Audition <ul><ul><li>Audition </li></ul></ul><ul><ul><ul><li>the sense of hearing </li></ul></ul></ul><ul><ul><li>Frequency </li></ul></ul><ul><ul><ul><li>the number of complete wavelengths that pass a point in a given time </li></ul></ul></ul><ul><ul><li>Pitch </li></ul></ul><ul><ul><ul><li>a tone’s highness or lowness </li></ul></ul></ul><ul><ul><ul><li>depends on frequency </li></ul></ul></ul>
  26. 26. The Intensity of Some Common Sounds
  27. 28. Audition- The Ear <ul><li>Outer Ear </li></ul><ul><ul><li>Auditory Canal </li></ul></ul><ul><ul><li>Eardrum </li></ul></ul><ul><li>Middle Ear </li></ul><ul><ul><li>hammer </li></ul></ul><ul><ul><li>anvil </li></ul></ul><ul><ul><li>stirrup </li></ul></ul><ul><li>Inner Ear </li></ul><ul><ul><li>oval window </li></ul></ul><ul><ul><li>cochlea </li></ul></ul><ul><ul><li>basilar membrane </li></ul></ul><ul><ul><li>hair cells </li></ul></ul>
  28. 29. Audition <ul><li>Place Theory </li></ul><ul><ul><li>the theory that links the pitch we hear with the place where the cochlea’s membrane is stimulated </li></ul></ul><ul><li>Frequency Theory </li></ul><ul><ul><li>the theory that the rate of nerve impulses traveling up the auditory nerve matches the frequency of a tone, thus enabling us to sense its pitch </li></ul></ul>
  29. 30. Audition <ul><li>Conduction Hearing Loss </li></ul><ul><ul><li>hearing loss caused by damage to the mechanical system that conducts sound waves to the cochlea </li></ul></ul><ul><li>Nerve Hearing Loss </li></ul><ul><ul><li>hearing loss caused by damage to the cochlea’s receptor cells or to the auditory nerve </li></ul></ul><ul><li>Older people tend to hear low frequencies well but suffer hearing loss for high frequencies </li></ul>
  30. 31. Touch <ul><li>Skin Sensations </li></ul><ul><ul><li>pressure </li></ul></ul><ul><ul><ul><li>only skin sensation with identifiable receptors </li></ul></ul></ul><ul><ul><li>warmth </li></ul></ul><ul><ul><li>cold </li></ul></ul><ul><ul><li>pain </li></ul></ul>
  31. 32. Pain <ul><li>Gate-Control Theory </li></ul><ul><ul><li>theory that the spinal cord contains a neurological “gate” that blocks pain signals or allows them to pass on to the brain </li></ul></ul><ul><ul><li>“ gate” opened by the activity of pain signals traveling up small nerve fibers </li></ul></ul><ul><ul><li>“ gate” closed by activity in larger fibers or by information coming from the brain </li></ul></ul>
  32. 33. Taste <ul><li>Taste Sensations </li></ul><ul><ul><li>sweet </li></ul></ul><ul><ul><li>sour </li></ul></ul><ul><ul><li>salty </li></ul></ul><ul><ul><li>bitter </li></ul></ul><ul><li>Sensory Interaction </li></ul><ul><ul><li>the principle that one sense may influence another </li></ul></ul><ul><ul><li>as when the smell of food influences its taste </li></ul></ul>
  33. 34. Smell Receptor cells in olfactory membrane Nasal passage Olfactory bulb Olfactory nerve
  34. 35. Body Position and Movement <ul><li>Kinesthesis </li></ul><ul><ul><li>the system for sensing the position and movement of individual body parts </li></ul></ul><ul><li>Vestibular Sense </li></ul><ul><ul><li>the sense of body movement and position </li></ul></ul><ul><ul><li>including the sense of balance </li></ul></ul>