The Visual System Kelley Kline Phd Florida State U视系统凯利克莱恩博士——佛罗里达州立大学.pptVIP

The Visual System Dr. Kline FSU What stimuli are required for vision? Light- which can be thought of as discrete particles (photons) or traveling waves. Human Visible Spectrum Humans can detect waves of energy traveling through space between 380 760 nanometers). Wavelengths outside this spectrum are undetectable to the human eye. Some organisms do detect wavelengths outside our visible spectrum. E.g., Rattlesnakes detect in infrared!; bees detect ultraviolet light. Electromagnetic Radiation What are the 2 properties of light that influence visual perception? 1. Wavelength is associated with our perception of color. 2. Intensity is associated with our perception of “brightness.” Reflectance of light Light is reflected off of the surface of objects to the eye. Light energy is converted into neural energy then processed by the brain. Parts of the eye Outer Layer 1. Sclera: White fibrous layer 2. Cornea: the clear protruding structure in the front of the eye that is curved. Bends light rays is responsible for 70-80% of eye’s focusing ability. Cornea Middle Layer 1. Choroid: vascularized layer that provides nutrition for retinal cells. Is located between the retina sclera. 2. Pigment epithileum: a black pigment found between the choroid retina. **Traps photons from light to prevent scattering of photons along the retina, which reduces distortion. Middle layer (contd.) 3. Iris: smooth ring of muscle with a central opening (pupil). Gives us our eye color! 4. Pupil: Pupil changes in size depending on intensity of light. -Intense light, small constricted pupils -Dim light, dilated pupils 5. Lens: focuses light on retina (convex). -lens is round (nearby objects) -lens is flatter for distant objects Inner layer 1. Retina: contains receptor cells needed for neural processing of light. A. Fovea: indentation on retina. -fine discrimination; colo