For several decades, isovist field theory (also known as viewshed analysis) has been an increasingly popular method of representing visual space in architectural and geographical analyses. Little attempt has been made, though, to apply this method to the psychology of perception, despite its marked similarity to James Gibson's notions of vistas and transitions within the optical array. To this end, in an initial experiment, priming images of a particular viewpoint towards a portion of the visual space were presented. Subjects were significantly (p<0.05) more accurate in reproducing the spatial locations of objects in the scene when a briefly presented view of the objects (300ms) was taken from within the viewshed of a primed scene, compared to an equidistant view taken from outside the viewshed. The intervisibility of locations in space appears to act as a cue for orientation to the layout of the environment. In a second experiment, subjects showed a high degree of consistency in their judgments of the informativeness of particular viewpoints within a large, complex space. No significant change in preference was found for views which maximized the overall area of visibility, but informativeness ratings were greatest for those views which contained transitions between adjacent vistas. Further analysis revealed that the viewpoints judged to be most valuable for navigation and orientation can often be represented by unique isovists (those which completely define the space that can be seen from a particular vantage point) within the spatial layout of the structure. Methods for defining “functional isovists” (changes in the viewshed across time and movement of an agent) are developed, and can account for the results of this experiment. The relationship between isovist methods of quantifying space and human perceptions will be discussed, as well as the usefulness of this technique for interpreting the spatial experience of active agents in the environment.
Funded in part by a fellowship from the J. William Fulbright Foundation