Wall patterns influence the perception of interior space.

The texture of an object's surface influences its perceived spatial extent. For example, Hermann von Helmholtz reported that a square patch with black and white stripes appears elongated perpendicular to the stripes' orientation. This time-honoured finding stands in contrast with more recent recommendations by interior-design experts who suggest that stripe wall patterns make rooms appear elongated in the direction parallel to the stripes' orientation. In a series of four experiments, we presented stripe wall patterns and varied the orientation of the stripes (horizontal vs. vertical) and their density (number of stripes per degree of visual angle). Subjects estimated the width and height of stereoscopically presented interior spaces. Stripe patterns with higher densities made rooms appear both wider and higher than did stripe patterns with lower densities or plain walls. In contrast to both the predictions from the Helmholtz-square and the design guidelines, this effect was only weakly modulated by pattern orientation, in the sense that rooms appeared elongated in the direction parallel to the stripes' orientation. We conclude that object-based texture effects cannot be generalised to interior space perception. For a room's perceived spatial extent, pattern density is more important than pattern orientation.