Abstract
Visual short-term memory (VSTM) has been shown to have a limited capacity. Studies documenting this limitation have all presented objects in the same depth plane. Objects in our surroundings, however, are typically laid out at different depths. It is thus possible that the reported VSTM capacity limitation is restricted to a particular depth, and that our visual system is capable of holding more objects if they are placed at different depths. In a series of experiments using the change detection paradigm, we found that VSTM capacity increases when objects are laid out in two depth planes as compared to one depth plane. This increase in capacity was not a result of grouping, because when only one depth plane was present, no benefit was observed when objects were grouped into circles and squares, grouped into a stationary group and a moving group, or grouped into a left group and a right group at the same depth. These results indicate that depth plays an important role in determining VSTM capacity.