Boundary Extension in a virtual world

Boundary Extension (BE; Intraub Richardson, 1989, JEP:LMC, 15, 179-187) refers to a memory distortion in which observers appear to remember a greater expanse of a scene than was actually shown. For instance, if they are shown a close-up photograph of a child sitting on the stairs, they will later remember a wider-angle scene. Intraub and her colleagues suggest that BE is mediated by perceptual schemas that anticipate the probable contents of future views. The majority of BE studies have used photographs or line drawings. Here we used virtual reality (VR) to present 3D objects either in isolation (NOSCENE condition) or as the centre-piece of a virtual living room (SCENE condition). Observers were shown a 1 sec. view of each object from a particular viewing distance and orientation relative to the objects' vertical axis. After a 5 sec., blank retention interval, the same object/scene appeared but the viewing distance and orientation were randomized. Observers actively recreated the original viewpoint by updating their virtual position using a joystick-like device. For the SCENE condition a robust BE effect was observed, the magnitude of this error dropping sharply as initial viewing distance increased. In the NOSCENE condition observers underestimated their initial distance, a tendency that increased with viewing distance. Contrasting explanations based on either layout expansion or misjudged size/distance were explored in additional experiments. Discussion also focuses on the use of VR with it's ability to quickly and easily manipulate the presence/absence of both scene and object within and across trials