NUMNeglect: Embodied number cognition in spatial neglect

The concept of embodied cognition refers to the observation that bodily states directly affect abstract thinking and learning. In the field of numerical cognition, an impressive collection of evidence for embodied number cognition has accumulated. We now know that even complex symbolic operations like arithmetic are influenced by a wide range of sensori-motor processes such as finger control, body motion and visuo-spatial (over and covert) attention orienting. From these interactions it follows that certain clinical conditions affecting the bodily integrity can also modulate (numerical) cognition. Patients with spatial neglect after right-sided brain lesions not only have a bias to orient and interact in physical space,but they can also suffer from a similar bias when processing numbers (Zorzi et al., 2001; Dorrichi et al., 2005). Moreover recent studies indicate that hemi-neglect rehabilitation can counteract this bias in physical as well as in number space (e.g. Rossetti et al., 2004; Sallilas et al., 2009).

The present PhD-project aims to further our knowledge on embodied numerical cognition in young healthy adults and neglect patients. To this aim we will systematically investigate the effect on body movement on qualitatively different levels of number processing: number production (i.e. random number generation), number comparison (i.e. magnitude and parity judgment) and number computation (i.e. addition, subtraction, and multiplication).

First we will explore the effect of body movement on these different numerical processing levels in healthy adult participants. Then this design will be implemented in right brain-damaged patients with or without neglect. In a third step, we will use the recently developed neglect rehabilitation method called neck muscle vibration (NMV) as a means to induce illusory head movement in neglect patients. The effect of NMV on physical neglect and number processing will then be evaluated in a cross-over clinical design, allowing us to gain knowledge on the efficiency of this revalidation method, as well as on the effect of illusory head movement on numerical processing in neglect. Taken together we hope that these studies will help us understand how number concepts arise and how bodily states can affect their quality.