Abstract
Although visual space perception research has historically focused on the role of on-line egocentric distance cues, recent work has shown that spatial information remembered from previous glimpses can facilitate processing of distance cues. Here we investigated whether the benefit of remembered spatial information might depend on the duration available for extraction of distance cues. Targets were rectangular orange boards subtending a constant angular size across distances varying between 2.5-7m. Viewing was binocular and targets were seen in a well-lit, largely empty room. A first block involved brief presentations of the target (70, 120, 170, or 220 ms, manipulated between groups of n = 15), followed by a visual mask. Distance was indicated by blindfolded walking. A 10 sec glimpse of the room without target was then provided, to establish a strong memory of the environment. A second block of brief glimpses was conducted to assess improvement after the long glimpse, followed by a third block with longer (5 sec) viewing durations as a measure of asymptotic performance. The groups were well-matched in their asymptotic performance, with mean response versus distance slopes = 0.96. Only the 70 ms group showed a benefit of the longer glimpse between blocks 1 and 2 (p = .039), with mean response slopes increasing from 0.66 to 0.76 across blocks. Block comparisons for all other durations yielded ps > .16. This suggests that remembered spatial information, when available, is primarily used in the earliest stages of a glimpse.