In everyday life we constantly talk about objects in the world around us: we may enlist help in looking for an object (e.g., `Where are my keys?`); we may point out a surprising object in the environment (e.g., `Look at that billboard in front of the building!`); or, we may give instructions to put objects in certain locations (e.g., `Put the lamp to the left of the chair.`). In each case we must perform a mapping between the linguistic elements in the utterance and our perception of the objects and their relation in the world. For example, the words `lamp` and `chair` need to be mapped onto their appropriate referents in the world, and the relation `to the left of` needs to be mapped onto the spatial relationship between these objects. This project focuses on how linguistic spatial terms are mapped onto spatial relations in the environment. Two specific aspects of the process will be examined. The first is how spatial terms are mapped onto directions in space. This is an interesting topic because sometimes more than one mapping is possible. For example, in the utterance `Put the lamp to the left of the chair,` `left` could refer to the speaker's left side or to the chair's left side. Because these disagree for a speaker facing a chair, there is some ambiguity as to where the lamp should be placed. Understanding a potentially ambiguous utterance may therefore be difficult if all possible interpretations are considered. Previous research suggests that multiple interpretations of spatial relation terms are initially considered. In the present project one series of experiments uses an eye tracking methodology to examine the simultaneous activation more closely, with the additional goal of examining how the degree of disagreement among the varying interpretations influences the degree of difficulty in understanding the utterance. Another series of experiments examines how one interpretation is selected when multiple interpretations are initially activated. The specific question is whether the selection of one interpretation is accompanied or assisted by an inhibition of the other interpretations. The second aspect of the mapping process examined in the present project involves dividing up space around the objects into regions to which the relation term (e.g., `above`) does and does not apply. A series of experiments explores how such regions are defined, and examines factors that may influence the size of these regions, such as the conceptual size of the objects, the presence of other objects in the scene, or the functional relationship between the two objects. Together these experiments should further our understanding of the online interpretation of spatial relations. This has important implications theoretically for our understanding of the interface between language and spatial representation, and practically for our ability to use effective and unambiguous communication.
