CHAPTER 7 PERCEPTION CHAPTER OUTLINE Brain Mechanisms of Visual Perception: The visual system of the brain is arranged hierarchically. Information is analyzed at each level & results are passed on to the next level for further analysis. The primary visual cortex contains a map of the retina & hence, of the visual field. Visual images are broken down into small pieces, each analyzed by clusters of neurons that provide info about such features as lines, edges & colours. Particular regions of the 1 level of visual association cortex are responsible for the analysis of details of shape, colour, location & movement. The 2 level of visual association cortex contains regions that recognize 3-D objects & the objects location & direction of movement. Brain damage to a persons visual association cortex disrupts specific perceptual abilities, such as perception of common objects, faces, colours, movements & spatial locations. Perception of Form: The Gestalt organizational laws of proximity, similarity, good continuation, closure & common fate describe how grouping of elements of visual scene help it distinguish bw figure & ground objects & their backgrounds. Psychologists have proposed templates and prototypes to explain how we can recognize particular patterns of visual stimuli & thus identify particular objects. The fact that we can recognize complex objects such as faces as quickly as we can recognize simple geometric shapes suggests that the visual system performs many tasks at the same time. Cognitive research & research using computers provided evidence that the brain is a parallel processor. New models called neural networks have elements w properties similar to those of neurons.