The visual perception of outdoor angular spatial relationships

A single experiment evaluated younger and older observers' ability to judge angular spatial relationships in an ordinary outdoor environment. Previous research from multiple laboratories has found that the visual ability to perceive distance is either well-maintained or improves with advancing age. The present experiment investigated whether this age-related equivalence or superiority also occurs for other spatial abilities, such as the ability to judge angles. Thirty adults judged 12 angles formed from trees, signs, light poles, and stone benches. The observers' overall performance was good: 74% of the variance in the judged angles could be accounted for by variance in the physical stimulus angles (overall Pearson r correlation coefficient was 0.86). The judgments of the older observers were nevertheless more accurate than those made by the younger observers (Cohen's d was 0.72). A detailed analysis of the observers' judgments revealed consistent local distortions of particular stimulus angles such that some angles were perceived to be much larger than they actually were (physically), whereas other stimulus angles were perceived to be much smaller than their physical magnitude. These local distortions in perceived angle magnitude may be related to the presence of environmental features that are associated with (linear) perspective.