Thesis defense Florian Krause (Donders Series 167)

10 October 2014

Promotors: Prof.dr. H. Bekkering, Prof.dr. I. Toni; copromotor: Dr. O. Lindemann

Numbers and magnitude in the brain: A sensorimotor grounding of numerical cognition

In our modern society we are surrounded by numerical information every day – all day long. Understanding how our brain represents and processes this information is important for diagnostic and educational purposes alike. This thesis focuses on the underlying mechanisms of the representation of analogue magnitude information, both on a behavioural as well as a neural level. In particular, the embodied cognition hypothesis for numerical cognition and the related suggestion that the concept of numerical size is grounded in sensorimotor experiences with magnitude are explored.

The results of the reported behavioural and neuroimaging studies support this notion and provide new empirical evidence for a direct grounding of numerical size in sensorimotor magnitudes by means of a shared representation between numerical size, perceptual magnitude and motor magnitude. Importantly, compared to previous ideas on embodied numerical cognition, in which embodied representations rely on associating numerical size with magnitude-unrelated sensorimotor aspects (such as representations of the fingers or experiences with positional space), a direct grounding in sensorimotor magnitudes is qualitatively different, as it allows for a grounding of numerical magnitude information without leaving the magnitude domain.

In conclusion, the research presented in this thesis suggests that numerical cognition relies on multiple embodied representations of numerical size and, in particular, stresses the importance of sensorimotor experiences with size and magnitude in everyday life for our understanding of analogue numerical magnitude information.