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Myers EXPLORING PSYCHOLOGY

Myers EXPLORING PSYCHOLOGY. Module 14 Introduction to Sensation and Perception: Vision James A. McCubbin, PhD Clemson University Worth Publishers. Sensation. Sensation the process by which our sensory receptors and nervous system receive and represent stimulus energy Perception

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Myers EXPLORING PSYCHOLOGY

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  1. Myers EXPLORING PSYCHOLOGY Module 14 Introduction to Sensation and Perception: Vision James A. McCubbin, PhD Clemson University Worth Publishers

  2. Sensation • Sensation • the process by which our sensory receptors and nervous system receive and represent stimulus energy • Perception • the process of organizing and interpreting sensory information, enabling us to recognize meaningful objects and events

  3. Sensation • Our sensory and perceptual processes work together to help us sort out complex images

  4. Sensation • Bottom-Up Processing • analysis that begins with the sense receptors and works up to the brain’s integration of sensory information • Top-Down Processing • information processing guided by higher-level mental processes • as when we construct perceptions drawing on our experience and expectations

  5. Sensation: Basic Principles • Psychophysics • study of the relationship between physical characteristics of stimuli and our psychological experience of them • Light- brightness • Sound- volume • Pressure- weight • Taste- sweetness

  6. Sensation: Thresholds • Absolute Threshold • minimum stimulation needed to detect a particular stimulus 50% of the time • Difference Threshold • minimum difference between two stimuli required for detection 50% of the time • just noticeable difference (JND)

  7. 100 Percentage of correct detections 75 50 Subliminal stimuli 25 0 Low Absolute threshold Medium Intensity of stimulus Sensation: Thresholds • Subliminal • when stimuli are below one’s absolute threshold for conscious awareness

  8. Sensation: Thresholds • Weber’s Law • to be perceived as different, two stimuli must differ by a constant minimum percentage (rather than a constant amount) • light intensity- 8% • weight- 2% • tone frequency- 0.3%

  9. Now you see it, now you don’t! Sensory Adaptation- diminished sensitivity as a consequence of constant stimulation

  10. Vision • Transduction • conversion of one form of energy to another • in sensation, transforming of stimulus energies into neural impulses • Wavelength • the distance from the peak of one wave to the peak of the next

  11. Vision • Hue • dimension of color determined by wavelength of light • Intensity • amount of energy in a wave determined by amplitude • brightness • loudness

  12. The spectrum of electromagnetic energy

  13. Great amplitude (bright colors, loud sounds) Short wavelength=high frequency (bluish colors, high-pitched sounds) Long wavelength=low frequency (reddish colors, low-pitched sounds) Small amplitude (dull colors, soft sounds) Vision: Physical Properties of Waves

  14. Vision

  15. Vision • Accommodation- the process by which the eye’s lens changes shape to help focus near or far objects on the retina • Retina- the light-sensitive inner surface of the eye, containing receptor rods and cones plus layers of neurons that begin the processing of visual information

  16. Retina’s Reaction to Light- Receptors • Rods • peripheral retina receptors • detect black, white and gray • for peripheral or twilight conditions • Cones • receptors near center of retina • fine detail and color vision • for daylight or well-lit conditions

  17. Retina’s Reaction to Light • Optic nerve • nerve that carries neural impulses from the eye to the brain • Blind Spot • point at which the optic nerve leaves the eye, creating a “blind spot” because there are no receptor cells located there

  18. Receptors in the Human Eye Cones Rods Number 6 million 120 million Location in retina Center Periphery Sensitivity in dim light Low High Color sensitive? Yes No Vision: Receptors

  19. Pathways from the Eyes to the Visual Cortex

  20. Cell’s responses Stimulus Visual Information Processing • Feature Detectors • nerve cells in the brain that respond to specific features • shape • angle • movement

  21. Visual Information Processing • Parallel Processing • simultaneous processing of several aspects of a problem simultaneously

  22. Visual Information Processing • Trichromatic (three color) Theory • Young and Helmholtz • three different retinal color receptors • red • green • blue

  23. Visual Information Processing Opponent-Process Theory- opposing retinal processes enable color vision “ON” “OFF” redgreen greenred blueyellow yellowblue black white white black

  24. Visual Information Processing • Color Constancy • Perceiving familiar objects as having consistent color, even if changing illumination alters the wavelengths reflected by the object

  25. Color-Deficient Vision • People who suffer red-green dificiency have trouble perceiving the number within the design

  26. Opponent Process: Afterimage Effect

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