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Vision

Vision . Vocabulary. Transduction Structure of the eye Accommodation Dark Adaptation Retinal Disparity Wave length Amplitude Saturation Hue Radiant light Reflected Light Trichromatic theory . Opponent process theory Color afterimage Color deficiencies

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Vision

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  1. Vision

  2. Vocabulary • Transduction • Structure of the eye • Accommodation • Dark Adaptation • Retinal Disparity • Wave length • Amplitude • Saturation • Hue • Radiant light • Reflected Light • Trichromatic theory • Opponent process theory • Color afterimage • Color deficiencies • Monocular Cues v Binocular Cues • Young – Helmholtz Theory • Nearsightedness/Farsightedness • Parallel Processing • Acuity

  3. Demonstration Time

  4. Optical Illusion What do you see?

  5. Overview • How the nervous system processes light • Helps us adapt to the environment around us • Detects targets • Detects threats • Detects changes in the environment

  6. Structure • “Eye is similar to a video camera” • Gathers light • Focuses objects • The change of focal length is called accomodation • Converts info into neural signals • Sends signals to be processed • Extracts info from light waves in a process called transduction (the transformation of one kind of energy into another)

  7. Structure(continued) • Retina: light sensitive located in the back of the eye • Fovea: small section of retina that contributes to sharp vision • Lens: focuses light onto the retina • Photoreceptors: convert light energy into neural impulses • Located in the retina • Performs most of the eye’s main functions • Two types of receptors • Rods: detects light at a low level (dark adaptation) • helps you see in the dark but cannot sense color • Cones: processes color; helps you see in bright light

  8. Structure(continued) • Bipolar cells collect impulses rods and cones to deliver to ganglion cells • Ganglion cells take these impulses and transports them from the eye to the brain • Bundle of ganglion cells is called an axon nerve • None of these three are directly responsive to light

  9. Demonstration Time

  10. Blindspots • Places where you have no photoreceptors and the optic nerve exits the eye • To substitute for blind spots one eye fills in what the other misses • This difference in what each eye can see is called retinal disparity http://serendip.brynmawr.edu/bb/blindspot1.html

  11. What about the brain? • two main parts of the brain • Occipital lobe where visual center of the brain is located • Forebrain: houses the thalamus; it controls the sensory functions. • Thalamus relays sensory impulses of the cerebral cortex • Visual cortex: located in the thalamus cerebral cortex; receives the visual data from the thalamus • Optic chiasm: the crossing of the optic nerves from the two eyes at the base of the brain .

  12. Color • Color • Psychological sensation created by info stored in the brain and wavelengths of visible light (also known as hue) • How vivid a color appears is called its saturation • Light • Radiant Light: transmitted in a wave motion • Reflected Light: a light ray that bounces off a reflective surface at the exact angle at which it contacted the surface.

  13. Electromagnetic Energy • Electromagnetic energyis another word for pure energy • Released in wave lengths (distance it takes to make one wave cycle) • when talking about the strength of a wave length you refer to its amplitude • Electromagnetic spectrum: range of electromagnetic energy (infared – radio) • Visible spectrum: portion of EMS that our eyes process

  14. Electromagnetic Spectrum

  15. Why do we see color? • Young-Helmholtz theory: the photoreceptor cells in the eyes and other cells work together to enable a color vision • Trichromatic theory: the idea that colors are sensed by three different types of cones sensitive to light in the red, blue, and green wavelengths. • It explains the earliest stage of color sensation. • Opponent process theory: the idea that cells in the visual system process colors in complementary pairs

  16. Demonstration Time

  17. Disorders http://www.shileyeyelasik.com/video/player/9755-common-vision-problems. • Usually genetic but can be caused by trauma • Most common are color deficiencies • lack of ability to distinguish color • Also known as color blindness • Most common form is trouble distinguishing red and green • Lack of acuity or sharpness of vision can lead to… • Nearsightedness: unable to see objects from a distance clearly • Farsightedness: unable to see objects that are close properly • Monocular cue: ability to recognize the distance of an object • Binocular cue: the ability to recognize when an object is near or far

  18. That concludes our presentation… Any Questions?

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