Abstract. We present an collaborative approach towards a detailed understanding of the usage of pointing gestures accompanying referring expressions. This effort is undertaken in the context of human-machine interaction integrating empirical studies, theory of grammar and logics, and simulation techniques. In particular, we attempt to measure the precision of the focussed area of a pointing gesture, the so-called pointing cone. The pointing cone serves as a central concept in a formal account of multi-modal integration at the linguistic speech-gesture interface as well as in a computational model of processing multi-modal deictic expressions.