The authors examine the tendency to prefer shapes perceived as regular and homogeneous when a person interactds with architectural structures and environments. Instinctual components. - environmental components (the - -latter being subdivided into components for, learning or for saturation)and particular control needs, depending on personality, are identified - -as factors which contribute in determining this tendency. Reference ismade to the behaviour of adult subjects of both sexes interacting with; a) buildings with acute or obtuse corners;- - b) buidinga with tilted wall; - - c) flat surfaces rotated in the third dimension; d) perspective graphic representation of tunnels; - e) long oblique tunnels containing escalators; - -- f) leaning buildings; - g) irregular-shaped rooms.