Presents a mathematical technique for building perceptual models of urban areas. Uses techniques to model perceptual neighborhoods within a city and to explore how residential burglary rates vary between the interiors and borders of the neighborhood. (Author/MA)

Eye contact with a stranger was relatively rare in center-city Philadelphia, more common in a suburb, and very common in a small rural town. Speaking occurred only with eye contact. These results suggest that social interaction in the city is an adaptation to overload of interpersonal contacts. (Author/MA)