1.6.B—Explain how the structures and functions of the visual sensory system relate to behavior and mental processes.…

Explain how the structures and functions of the visual sensory system relate to behavior and mental processes. UNIT 1 Biological Bases of Behavior

• The retina is the photosensitive surface at the back of the eye. Cells in the retina capture visual information that is transduced to the brain for processing. Evidence of incomplete images captured by the retina is demonstrated by the presence of the blind spot, where the visual nerve exits the eye. The brain fills in the gaps in the incomplete retinal images to perceive a relatively complete picture of the world.
• Visual stimuli are focused onto the retina by the lens via a process called accommodation. When this process is altered, nearsightedness or farsightedness can result.
• Cells that lie in the periphery of the eye and detect shapes and movement, but not color, are called rods. These cells are mainly activated in low-light environments. These cells play a role in light and dark adaptation.
• Color vision is explained by both the trichromatic theory and the opponent-process theory.
  • i. Photoreceptor cells located in the fovea of the eye that process color and detail are called cones. Researchers have identified blue (detecting short wavelengths), green (detecting medium wavelengths) and red (detecting long wavelengths) cones in the retina.
  • ii. Afterimages result when certain ganglion cells in the retina are activated while others are not. The ganglion cells involved in this opponent process are red/green, blue/ yellow/ and black/white.
  • iii. Color vision deficiency involves damage or irregularities to one or more cones or ganglion cells (red/green, blue/ yellow). Color vision deficiency includes dichromatism or monochromatism.
• Damage to parts of the brain responsible for vision (mainly the occipital lobes) can result in disorders such as prosopagnosia (face blindness) and blindsight.