AbstractAdults readily detect structural coherence and it was recently discovered that young infants respond to pictures of impossible figures as well with increased looking, oculomotor activity and manual exploration (Shuwairi et al., 2007, Shuwairi & Johnson, 2013). Past research has demonstrated discrepancies between stimuli containing novel impossible figures suggesting that this increased attention could be associated with other perceptual properties such as symmetry or complexity, rather than inherent knowledge of global incoherence. The goal of this study is to evaluate the nature of children’s conceptual knowledge of the global properties of real 3D objects and to clarify how and when young children achieve an understanding of the various perceptual dimensions of objects, such as complexity, symmetry and coherence. A series of line drawings will be presented, each varying along one of the above-mentioned perceptual dimensions. Children will be instructed to sort all the shapes into two groups based on what seems most natural. After “free-sorting”, children are given a brief tutorial on particular aspects of shape geometry and instructed to sort the figures by that perceptual dimension to draw attention to the pertinent properties of these objects (e.g., drawing a butterfly while emphasizing equivalent left-right sides). Children are expected to engage in free-sorting the shapes based on low-level shape similarities (like round vs. straight edges) rather than higher-level categorical properties such as “impossibility” and “symmetry along the vertical midline.” However, across all sets of shapes, children are expected to show improved categorization skills on these sorting tasks after instructions are given.