From the light that falls on the retina, the visual system must extract meaningful information about what is where in our environment. At an early stage in this process, it analyzes the incoming sensory data along many dimensions of pattern vision. This book describes the current knowledge about this stage of visual processing, focusing both on psychophysical experiments measuring the detection and identification of near-threshold patterns and on the mathematical models used to draw inferences from such experimental results. Neurophysiological evidence is presented and compared critically to the psychophysical evidence. Orientation, spatial frequency, direction of motion, and eye of origin are among the many dimensions of spatiotemporal pattern vision for which experimental results and mathematical models are reviewed. Introductory material on psychophysical methods, signal detection theory, and the mathematics of Fourier analysis is also given. The preface gives a guide to the organization of the book and to what parts of the book can be read independently of one another. The last two chapters contain lists of references organized by dimensions of pattern vision. An appendix at the end of the book lists the assumptions used in the models both in order of appearance and in groups according to function.