The use of spatial relations in referring expression generation

There is a prevailing assumption in the literature on referring expression generation that relations are used in descriptions only 'as a last resort', typically on the basis that including the second entity in the relation introduces an additional cognitive load for either speaker or hearer. In this paper, we describe an experiemt that attempts to test this assumption; we determine that, even in simple scenes where the use of relations is not strictly required in order to identify an entity, relations are in fact often used. We draw some conclusions as to what this means for the development of algorithms for the generation of referring expressions.