Norma Van Surdam Graham

She studies visual perception, specifically low-level processes of pattern and form perception. Her early work helped develop the concept of multiple channels sensitive to different ranges of spatial frequency. (A pattern of narrow stripes or fine-grained texture contains predominantly high spatial frequencies, while a pattern of large-sized elements contains predominantly low spatial frequencies. The physiological substrate for these channels is probably cortical area V1.) Her recent research extends the spatial-frequency channel model to include complex (non-Fourier) channels and inter-channel inhibition (normalization), particularly to explain the segmentation of different regions in visual scenes.