SKETCHING BEHAVIOUR IN OBJECT RECALL AND OBJECT COPYING.

Previous research investigating sketching processes during object visualisation and design has indicated that drawing occurs in a primarily part-bypart manner, whereby the component volumetric structures of objects appear to dominate the organisation of ongoing activity. Some non-part-by-part sketching does arise, however, and appears to be closely linked with those parts of objects that possess multiple functionality (i.e., multifunctional parts). This suggests that functional knowledge may at times play a critical role in the reasoning underlying sketch production. The present experiment aimed to further investigate the influence of long-term memory and functional knowledge on sketching. The study manipulated whether presented objects containing both multifunctional and unifunctional parts had to be sketched from memory or simply copied. Analyses failed to indicate reliable effects on levels of non-part-by-part sketching of drawing condition (recall vs. copying), part type (multifunctional vs. unifunctional), or an interaction between these factors. However, reliable evidence was obtained indicating that part-occlusion and part-multifunctionality were determinants of nonpart- by-part production under both object-recall and object-copying instructions. We interpret these effects as demonstrating an important role for the strategic use of a drawing technique aimed at maintaining representational accuracy of the whole object during the sketching of complex parts.