Tourtouri, Elli; Delogu, Francesca; Crocker, Matthew W.

The interplay of specificity and referential entropy reduction in situated communication

10th Annual Embodied and Situated Language (ESLP) Conference, Higher School of Economics, Moscow, Russia, 2017.

In situated communication, reference can be established with expressions conveying either precise (Minimally-Specified, MS) or redundant (Over-Specified, OS) information. For example, while in Figure 1, “Find the blue ball” identifies exactly one object in all panels, only in the top displays is the adjective required. There is no consensus, however, concerning whether OS hinders processing (e.g., Engelhardt et al., 2011) or not (e.g., Tourtouri et al., 2015). Additionally, as incoming words incrementally restrict the referential domain, they contribute to the reduction of uncertainty regarding the target (i.e., referential entropy). Depending on the distribution of objects, the same utterance results in different entropy reduction profiles: “blue” reduces entropy by 1.58 bits in the right panels, and by .58 bits in the left ones, while “ball” reduces entropy by 1 and 2 bits, respectively. Thus, the adjective modulates the distribution of entropy reduction, resulting in uniform (UR) or non-uniform (NR) reduction profiles. This study seeks to establish whether referential processing is facilitated: a) by the use of redundant pre-nominal modification (OS), b) by the uniform reduction of entropy (cf. Jaeger, 2010), and c) when these two factors interact. Results from inspection probabilities and the Index of Cognitive Activity — a pupillometric measure of cognitive workload (Demberg & Sayeed, 2016) — indicate that processing was facilitated for both OS and UR, while fixation probabilities show a greater advantage for OS-UR. In conclusion, efficient processing is determined by both informativity of the reference and the rate of entropy reduction.