Processing of the Global and Local Dimensions of Visual Hierarchical Stimuli by Humans (Homo sapiens), Chimpanzees (Pan troglodytes), and Baboons (Papio papio)

Abstract

Awell-known phenomenon in the literature on human perception is the global precedence effect, which was initially reported by Navon in 1977. Navon pre- sented human subjects with hierarchical stimuli such as those shown in Fig. 1. These were large letters (globallevel) made up ofsmaller letters (locallevel) which had to be identified as quickly as possible. Use ofthese forms showed that response latencies were shorter on average for the global trials, involving identification of the globalletter,than for the local trials,involving identification ofthe localletter. It was also shown that response times (RTs) in global trials remained unchanged whatever the identity of the letter shown at the locallevel,whereas RTs in local trials were higher when the global and locallevels showed different letters than when they showed the same letter. On the basis of these results, Navon (1977) suggested that the processing ofvisual stimuli byhumans proceeds from an analy- sis ofthe global structure ofthe visual form prior to the analysis ofits more local details.According to Navon (1977),this global-to-Iocal order ofvisual processing is a general trait ofvisual perception,and is independent ofthe use ofhierarchical letter stimuli，的 revealedbythe title ofhis article“Forest before the tree: the prece- dence of global features in visual perception."