Dissociating developmental trajectories of part-specific and part-relational processing in object recognition

We have previously found evidence for a remarkably late consolidation of configural (part-relational) relative to part-based object recognition (Jüttner,Wakui, Petters, Kaur and Davidoff, 2012 Developmental Psychology in press). Here we present a series of experiments that systematically confine the origin of the delayed development of part-relational processing. School children aged 7–12 and adults were tested in 3-AFC tasks to judge the correct appearance of upright and inverted presented newly learned multi-part objects that had been manipulated either in terms of individual parts or part relations. Manipulations were constrained to either categorical or metric changes of either individual parts or part relations. For categorical changes, even the youngest children were close to adult levels of performance for recognizing both changes of parts and part relations. By contrast, performance for recognizing metric changes of part relations was distinctly impaired in young children relative to that for recognizing metric changes of individual parts, and approached the latter not until 11–12 years. This distinctly retarded onset of part-relational processing was observed for both manipulations involving relative size and relative position. The results suggest a generic developmental dissociation of categorical and metric processing for part relations, but not for individual parts, in early adolescence.