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. 1999 Sep 28;96(20):11681–11686. doi: 10.1073/pnas.96.20.11681

Figure 3.

Figure 3

A computational model of attentional processes in third-order motion embedded in a more comprehensive model of visual processing. The inputs to the model are stimuli and attentional instructions; the computational output is a direction-of-motion judgment. There are two types of inputs: visual stimuli and attentional instructions. Stimulus inputs are analyzed along various dimensions: depth, orientation, texture (TG, texture grabber), and color channels are indicated. For the present experiments, it is only necessary to consider color (red and green) and texture processing. Instructions to attend to a color are assumed, in only the salience pathway, to increase the gain of the attended color signal to a value greater than 1.0, so that the attended color input is amplified by 1 + αg or 1 + αr. The “Salience Map” is the sum of all the stimulus inputs in the salience pathway; its output goes to the “Motion III” (third-order) computation, and also joins the stimulus inputs in the object-processing pathway. Motion III is represented as a Reichardt model (24); it produces a real-valued output that indicates a direction of motion and is perturbed by additive noise (N). “sf” denotes a spatial frequency filter; “tf” denotes a temporal frequency filter. A decision process outputs a response “Right” if its input is greater than a criterion, and “Left” otherwise. The third-order motion signal is also available to subsequent perceptual processes, as indicated.