The role of mental representations of space and fingers in number processing

Andres, Michael [UCL]

A core property of number words is that they are organized in sequence and their value is given by their relative position in the sequence. Children often use fingers and spatial cues as external aids for learning the number word sequence and the arithmetic procedures. I will present evidence from psychophysical, eye-tracking and interference studies showing that adults keep on relying on internal representations of space and fingers when they mentally process number words or when they solve arithmetic problems. I will first examine how finger movements interfere with mental arithmetic while looking at the effect of typical parameters of finger counting, such as movement direction and sequentiality. I will then present what spatial judgements and eye movements tell us about the role of spatial attention in number processing and arithmetic problem solving. I will finally confront the results of the reviewed experiments with existing accounts of the interactions between number, space and finger representations. I will propose that these interactions involve working memory mechanisms triggered by linguistic aspects of number processing, including the serial order of number words, their organization in units and decades, and the polarity of arithmetic signs.