The Neural Control of Vision
M. The Processing of Shape

We have a remarkable ability to recognize faces. It had been thought that our ability to do so depends heavily on high spatial frequency analysis, the ability to extract fine detail from the visual scene. It came as quite a surprise to realize that face recognition relies heavily on low-spatial frequency analysis. Figure 66 provides an example of this. Looking at this figure one can recognize the faces when one squints or looks at it from a distance, which minimize the high spatial frequencies contained in the figure.