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Sensation and Perception

Sensation and Perception

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Sensation and Perception

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  1. Sensation and Perception

  2. “Everything you see or hear or experience in any way at all is specific to you. You create a universe by perceiving it, so everything in the universe you perceive is specific to you.” – Douglas Adams

  3. Sensation • The process of taking in information from the environment

  4. Transduction • The process of changing raw sensory data into an electrochemical message that will be sent to the brain for interpretation.

  5. Perception • How we recognize, interpret, and organize our sensations

  6. Input comes primarily from these five external senses: • Visual (Eyes) • Audio (Ears) • Cutaneous/Tactile (Touch) • Olfaction (Smell) (Nose) • Gustation (Taste) (Tongue)

  7. Kinesthetic Sense • The kinesthetic sense monitors the position and movements of muscles, bones, and joints. Receptors in the joints and tendons send the brain information about the angle of your limbs.

  8. Vestibular Sense • The system for balance. • Fluid in the semicircle canals of the inner-ear maintain the body’s sense of balance.

  9. Detection Threshold or Absolute Threshold • The minimum intensity of energy required to produce sensation in a receptor cell at least 50% of the time

  10. Difference Threshold or Just Noticeable Difference • The smallest change in stimulation that you can detect

  11. Weber’s Law • The greater the magnitude of the stimulus, the larger the difference must be in order to be noticed • IE. If you are carrying 20 lbs. and add 5 lbs., it’s noticeable. If you are carrying 100 pounds and add 5 pounds, it may not be noticeable. You may need to add 20 lbs. to 100 pounds to make it noticeable.

  12. Sensory Adaptation • Diminished sensitivity as a result of constant and unchanging stimulation. • You jump into a swimming pool of cold water, but eventually you “get used to it”. Or, you wear your glasses so often that you sometimes forget that they are on.

  13. Subliminal Perception • Thresholds imply that there must be stimulus below and beyond our current levels of detection. Can human behavior be influenced by stimulus that is below or beyond our level of awareness? Subliminal Perception

  14. Extrasensory Perception • Some people claim to have extra powers of perception, or the ability to respond to an unknown event that is not presented to any of the known senses. • Parapsychology

  15. Examples of Extrasensory Perception • Telepathy: Transfer of information on thoughts or feelings between individuals by means other than the five classical senses • Precognition: Perception of information about future places or events before they occur. • Clairvoyance: Obtaining information about places or events at remote locations, by means unknown to current science.

  16. Does ESP Exist? • Remote Viewing? • Telepathy?

  17. Paranormal Activity • A&E Series Paranormal State • A&E Series Psychic Kids

  18. Visual Sensation

  19. How Do We See? • Visual Sensation and Perception • Vision And Behavior

  20. Human Eyeball

  21. Cornea • transparent protective coating over the front part of the eye

  22. Iris • the colored part of the eye – this muscle dilates or contracts the pupil to allow more or less light to enter

  23. Pupil • the small, adjustable center of the iris that allows light to enter the eye

  24. Lens • flexible enough to focus on objects near or far (accommodation) – if an object is very close is gets smaller and rounder; if an object is further away, it get larger and wider

  25. Retina • The inner lining of the back of the eyeball. The lens focuses an image from the outside world on the retina, and the retina in turn transduces the image.

  26. Fovea • On the retina, directly behind the lens. The area of sharpest picture.

  27. Acuity – the sharpness of vision • Nearsightedness – the misshapen eyeball focuses light rays in front of the retina – you will see near objects well, but not far away objects • Farsightedness – the light rays from nearby objects reach the retina before they have been focused – you will see far objects better than near objects

  28. Rods and Cones • In the retina. Rods determine shades of light and dark and detect motion. Cones determine color.

  29. Optic Nerve • Carries the transduced visual information from the eye and sends it to the brain for processing.

  30. Blind Spot • The area closest to the optic nerve, that has no receptor cells. Also known as the optic disc.

  31. Optic Chiasm • The point in the brain at which messages from the visual fields are split to the appropriate areas of the brain • Prosopagonosia - stroke victim disorder in which victims cannot recognize faces, but can still see well and recognize emotions on faces

  32. Stereopsis (Contralateral Shift)

  33. Color Vision • There are two theories of color vision: • Trichromatic Theory • Opponent-Process Theory

  34. Young-Helmholtz TheoryTrichromatic Theory • Rods and cones are pre-set to be sensitive to RED, GREEN, and BLUE. All of the colors that we see are combinations of those three colors.

  35. All other colors can be derived by combining these three.

  36. Opponent-Process Theory • Sensory receptors in the retina come in pairs: • Red/Green • Yellow/Blue • Black/White

  37. Opponent-Process Theory • If one sensor is stimulated, the other is inhibited • If one sensor is over-stimulated, and fatigues, the paired sensor will be activated, causing an afterimage • If a person is missing a particular pair of sensors, they will be colorblind to those hues • Dichromatic Color Blindness have difficulty seeing shades of red and green, or yellow and blue

  38. Hue – the color that we see is determined by the wavelength (the distance from one wave peak to the next) of the light wave that the eye is receiving

  39. Brightness is influenced by the height of the waves (amplitude) of light that are received by the eye

  40. The shorter the wavelength, more bluish colors • The longer the wavelength, more reddish colors • The higher the wave, more yellowish • The lower the wave, more greenish

  41. Color Range

  42. Visual Perception • Magic Fools The Eye

  43. The Visual Cliff

  44. Figure/Ground Dynamic • The ability to distinguish different objects from one another • Analyzing separate information allows us to re-act to each individual object accordingly • Camouflage – when figures blend into the background