Please join us for the next colloquium in our fall colloquium series.

Speaker:  Judith Degen (Stanford University)
Date & Time: November 4th at 3:30 pm
Place:  Education Bldg. rm. 433
Title:  Beyond “overinformativeness”: rationally redundant referring expressions

Abstract: What guides the choice of a referring expression like “the box”, “the big box”, or “the big red box”? Speakers have a well-documented tendency to add redundant modifiers in referring expressions (e.g., “the big red box” when “the big box” would suffice for uniquely picking out the intended object). This “overinformativeness” poses a challenge for theories of language production, especially those positing rational language use (e.g., in the Gricean tradition). We present a novel production model of referring expressions in the Rational Speech Act framework. Speakers are modeled as rationally trading off the cost of additional modifiers with the amount of information added about the intended referent. The innovation is assuming that truth functions are probabilistic rather than deterministic.

This model captures a number of production phenomena in the realm of overinformativeness, including the color-size asymmetry in probability of overmodification (speakers overmodify more with color than size adjectives); visual scene variation effects on probability of overmodification (increased visual scene variation increases the probability of overmodifying with color); and color typicality effects on probability of overmodification (speakers overmodify less with more typical colors). In addition to demonstrating how the model accounts for these qualitative effects, we present fine-grained quantitative predictions that are beautifully borne out in data from interactive free production reference game experiments.

We conclude that the systematicity with which speakers redundantly use modifiers implicates a system geared towards communicative efficiency rather than towards wasteful overinformativeness.