Abstract
The ability to estimate distant objects' sizes improves during childhood. Previous studies suggest that this developmental change results from increasing use of deliberate strategies that compensate for inaccurate perception of size at a distance. We conducted two studies to examine whether strategy use and size-estimation accuracy depend on verbal reasoning, spatial reasoning, and cognitive impulsivity. In each study, 6- to 9-year-olds viewed standard discs at 6.1 and 61 m, and chose from a set of nearby discs one that matched the standard. They were also asked to explain their choices. Study 1 (N = 26) included tests of verbal reasoning (WISC-III Verbal Similarities) and cognitive impulsivity (Matching Familiar Figures - 20). Study 2 (N = 32) included the verbal reasoning test and a spatial reasoning test (WISC-III Block Design). In both studies, children who reported deliberately adjusting their size estimates to take distance into account made more accurate far-distance estimates than those who reported no such strategy use. In addition, verbal reasoning and spatial reasoning were significantly correlated with far-distance strategy use and size estimation performance, and each kind of reasoning accounted for unique variance in strategy use. Cognitive impulsivity was not correlated with strategy use or size estimation accuracy. None of these variables was correlated with near-distance size estimation or strategy use. In sum, children who score high in verbal and/or spatial reasoning generally make accurate size estimates or overestimate size when viewing distant objects and report deliberately adjusting their size estimates to take distance in account; while children at comparable ages who score lower in these abilities tend to underestimate distant objects' sizes and report no strategy use. These findings suggest that developmental changes in far-distance size estimation accuracy may result from the development of reasoning abilities needed to use deliberate strategies for judging size.