The discrimination of structure in vectorgraphs: Local and global effects

Many recent electrophysiological studies have demonstrated specificity for orientation and position tuning in single units of the visual system. Psychophysical investigations have produced complementary evidence for orientation and position coding in vision which is usually interpreted in terms of the underlying neuronal properties. To date, no studies have endeavored to relate such “local” receptive field response profiles to more “global” or field-specific aspects of the input signal. In a series of experiments, we have investigated orientation/position sensitivity as a function of general orientation and position rules governing line element, or “vectorgraph,” displays. We have discovered with such vectorgraph images that individual element acuities are determined by the field structures present. These results show that there are specific “top-down” components even to basic orientation/position coding in the visual system