The "Backed Artefact Symmetry Index" (BASI) provides a measure with which to describe geometric variation in Australian backed artefacts, and Peter Hiscock has suggested that desert versions of this artefact type will be more symmetrical than their coastal counterparts. The re-excavated Serpent's Glen (Karnatukul) site and nearby site of Wirrili have produced a large assemblage of backed artefacts. These Western Desert assemblages allow for the testing of BASI. The backed artefacts demonstrate significantly more variability than predicted, demonstrating that all technological debates benefit from larger well-dated assemblages. The signalling information observed in these sites' pigment art repertoires, combined with this versatility in the toolkits, increases our understanding of the complexity of middle and late Holocene highly mobile foragers in the Australian arid zone.