Boundary extension: the role of magnification, object size, context, and binocular information

Boundary extension is a tendency to remember close-up scenes as if they extended beyond the occluding boundaries. The authors explored the contributing factors using brief retention intervals and computer-generated images. Boundary extension turns out to be more complex than previously thought and is not linked to the effects of image magnification and field-of-view changes. Although this is consistent with the idea that boundary extension is the product of the activation of a mental schema that provides information of what is likely to exist outside the picture boundaries, the authors also found that properties of the object at the center of the picture can affect boundary extension independently of the information at the boundaries. In a test of boundary extension using stereograms, the effect does not seem to depend on amount of perceived depth, suggesting a weaker link to perception of space than previously hypothesized.