Tool Use and the Representation of Peripersonal Space in Humans
© Oxford University Press, 2011. All rights reserved. One of the questions currently vexing researchers is whether peripersonal space is better conceptualized as being extended or as being projected following tool use? It may turn out that the answer to this question depends on what exactly the tool user must do with their tool. An equally important, if putatively orthogonal, issue concerns whether the effects of tool use are best conceptualized in terms of an attentional modification (i.e., prioritization) of a certain region of space (where the tool is being, or has been, used to perform an action) versus a change in spatial representation. While there is now an extensive body of evidence documenting tool use in a variety of animals, including recently in invertebrates, the focus of this chapter is primarily on the evidence collected from studies of tool use in humans and other primates. In particular, it reviews those studies that have used the cross-modal congruency task in order to investigate how the perception of peripersonal space changes during tool use. It also briefly compares these results to those that have emerged from neuropsychological research with clinical patients suffering from crossmodal extinction (i.e., from an impaired ability to report a stimulus on the contralesional side when it is presented at the same time as an ipsilesional stimulus).