Referring strategies in American Sign Language and English (with co-speech gesture): The role of modality in referring to non-nameable objects.

American Sign Language (ASL) and English differ in linguistic resources available to express visual-spatial information. In a referential communication task, we examined the effect of language modality on the creation and mutual acceptance of reference to non-nameable figures. In both languages, description times reduced over iterations and references to the figures' geometric properties ("shape-based reference") declined over time in favor of expressions describing the figures' resemblance to nameable objects ("analogy-based reference"). ASL signers maintained a preference for shape-based reference until the final (sixth) round, while English speakers transitioned toward analogy-based reference by Round 3. Analogy-based references were more time efficient (associated with shorter round description times). Round completion times were longer for ASL than for English, possibly due to gaze demands of the task and/or to more shape-based descriptions. Signers' referring expressions remained unaffected by figure complexity while speakers preferred analogy-based expressions for complex figures and shape-based expressions for simple figures. Like speech, co-speech gestures decreased over iterations. Gestures primarily accompanied shape-based references, but listeners rarely looked at these gestures, suggesting that they were recruited to aid the speaker rather than the addressee. Overall, different linguistic resources (classifier constructions vs. geometric vocabulary) imposed distinct demands on referring strategies in ASL and English.