Space constancy vs. shape constancy.

The perceived distance between objects has been found to decrease over time in memory, demonstrating a partial failure of space constancy. Such mislocalization has been attributed to a generalized compression effect in memory. We confirmed this drift with a pair of remembered dot positions but did not find a compression of perceived distance when the space between the dots was filled with a connecting line. When the dot pairs were viewed eccentrically the compression in memory was substantially less. These results are in line with a combination of factors previously demonstrated to cause distortion in spatial memory--foveal bias and memory averaging--rather than a general compression of remembered visual space. Our findings indicate that object shape does not appear to be vulnerable to failures of space constancy observed with remembered positions.