Stamps reported that the visual permeability of a boundary strongly infl uenced perceived enclosure, while boundary depth had almost no eff ect. Specifi cally, Stamps found that perceived enclosure demonstrates a highly negative correlation with distal permeability, a moderately negative correlation with proximate permeability, and a very low positive correlation with distal distance. The present comment suggests that environmental properties may aff ect physical perception, mental processes, and human behavior – not only in a physical but also in a social environment.