Delineate the functions of the magnocellular and parvocellular visual systems. Include information on origins and destinations.
What will be an ideal response?
The magnocellular and parvocellular visual systems are two main routes through which different types of visual information are transmitted and processed. Both systems originate in the retina, with the parvocellular system being made up of the axons of ganglion cells that receive information from the receptors in the fovea. The magnocellular system is made up of the axons of ganglion cells that receive information from the receptors in the periphery. The cells of the parvocellular system are smaller than those of the magnocellular system, and they make up the larger majority of ganglion cells. Their receptive fields are also small, circular, and color opponent, making them suitable for carrying information to the cortex about fine detail and color. The magnocellular system has receptive fields that are larger, circular, and brightness opponent, making them suitable for carrying information to the cortex about brightness contrast and movement. Both pathways travel to the lateral geniculate nucleus of the thalamus and then on to the primary visual cortex, where initial processing occurs. From there, each system dominates one of two pathways. The parvocellular system dominates the ventral stream, which travels from area V1 to V2 and V4 (where perception of color occurs), after which it travels to the inferotemporal cortex, where object and face recognition occurs. The magnocellular system dominates the dorsal stream, which travels from area V1 to V5/MT (where perception of movement occurs), after which it travels to the posterior parietal cortex, where objects are located in space.
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a. information processing approaches. c. behaviorism theories. b. organismic theories. d. mechanistic theories.
In Baillargeon's study in which infants were shown possible and impossible events involving a hand, a box, and a platform, the last stage of infants showing understanding of the principle of support was their belief that
a. as long as a hand touched an object, it would not fall. b. the box would not fall as long as some part of it touched the platform. c. the amount of contact between the box and the platform is important. d. the box would fall unless a significant portion of it remained in contact with the platform.