Generating relational references: what makes a difference?

When we describe an object in order to enable a listener to identify it, we often do so by indicating the location of that object with respect to other objects in a scene. This requires the use of a relational referring expression; while these are very common, they are relatively unexplored in work on referring expression generation. In this paper, we describe an experiment in which we gathered data on how humans use relational referring expressions in simple scenes, with the aim of identifying the factors that make a difference to the ways in which humans construct referring expressions.