PSY 200 1st Edition Lecture 5 Current Lecture Distributed Coding color perception The retina has three types of cones each type has a different pigment absorbs light around a particular wavelength We can measure how much light of different wavelengths a cone absorbs to determine that cones preferred wavelength Physics White light the light from the sun contains many wavelengths 3 Types of Cones S cones blue M cones green L cones red Each cell has all or none firing Distributed Coding a type of coding in which the information that constitutes a concept is spread amongst a number of constituent representations Lateral Inhibition Information from rods and cones is integrated in the ganglion cell of optic nerves Lateral inhibition when stimulated a neuron will inhibit the activity of neighboring cells Information from rods and cones is integrated in the ganglion cell of optic nerves Lateral inhibition results in enhancement of the edges of objects Visual system emphasizes change in environment Receptive fields become more complex Receptive field in ganglion cell of retina point of light Receptive field in occipital lobe orientation of edge Different Approaches to Visual Object Perception Feature integration theory Bottom up Recognition by Components Theory Bottom up Gestalt Approach Top down Feature Integration Theory These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute Object perception occurs in a sequence of stages in which features are first analyzed and then combines to result in perception of an object Features are color motion orientation shape etc Feature Detectors By examining how we perceive different visual features we can see whether it broadly fits with feature integration theory Feature are perceived at a preattentive stage Motion Area MT Medical Temporal and respond primarily to motion A given type of cell is specialized to see a given type of motion and if it fires that is the perception V1 most cells that are tuned to horizontal and vertical are excited ones that are tuned to 45 degrees are not excited MT a sub population of cells tuned to 45 degrees are excited The Binding Problem Neural evidence supports Feature Integration Theory Specialized areas for different properties color motion etc Treisman s Feature Integration Theory FIT The Details Models form two kind of maps Feature maps color orientation etc A master map of locations Within a feature map there is parallel processing a preattentive stage Feature from maps are bound by focal attention to a location in the mast map attentive stage