Spatial Representation: From Gene to Mind

This book presents a new thesis on the nature of cognitive disruption due to genetic deficit, relying on three basic principles of normal cognitive architecture and using Williams syndrome (WS) as a lens to understand the nature of spatial development, language learning, and the role of gene and mind in explaining these. The guiding principles are specialization of function in brain and cognition, the importance of developmental timing in the emergence of these functions, and the idea that genes can target cognitive systems. Previous perspectives on the nature of cognition in WS have tended to propose either strongly modular theories, or strongly empiricist theories, leading to very different proposals about what happens to cognition under genetic deficit. The present book navigates between these two positions and advocates a third: Spatial representations develop under tight architectural constraints that support the construction of detailed and domain-specific representations in people with WS. This leads to performance patterns that are no different from those of normal individuals at some point in development. The difference is that, in WS, the mechanisms of development proceed very slowly, with developmental arrest some time during adolescence. Those spatial functions that normally emerge early in life are, by this time, fully mature; whereas those that normally emerge along a lengthier developmental trajectory may never become mature, resulting in an overall profile that is similar to that of a much younger normally developing child. Surprisingly, this thesis explains not only much of the WS spatial profile, but also accounts for a broad range of findings on language in people with WS. Close examination of the WS cognitive profile, in the context of normal developmental trajectories, thus lead to a new understanding of the ways in which genetic deficits can target cognitive systems: Not by targeting the system itself, but rather, by derailing the timetables of otherwise normally developing functions.