To talk about space, spoken languages rely on arbitrary and categorical forms (e.g., left, right). In sign languages, however, the visual-spatial modality allows for iconic encodings (motivated form-meaning mappings) of space in which form and location of the hands bear resemblance to the objects and spatial relations depicted. We assessed whether the iconic encodings in sign languages guide visual attention to spatial relations differently than spatial encodings in spoken languages during message preparation at the sentence level. Using a visual world production eye-tracking paradigm, we compared 20 deaf native signers of Sign-Language-of-the-Netherlands and 20 Dutch speakers' visual attention to describe left versus right configurations of objects (e.g., "pen is to the left/right of cup"). Participants viewed 4-picture displays in which each picture contained the same 2 objects but in different spatial relations (lateral [left/right], sagittal [front/behind], topological [in/on]) to each other. They described the target picture (left/right) highlighted by an arrow. During message preparation, signers, but not speakers, experienced increasing eye-gaze competition from other spatial configurations. This effect was absent during picture viewing prior to message preparation of relational encoding. Moreover, signers' visual attention to lateral and/or sagittal relations was predicted by the type of iconicity (i.e., object and space resemblance vs. space resemblance only) in their spatial descriptions. Findings are discussed in relation to how "thinking for speaking" differs from "thinking for signing" and how iconicity can mediate the link between language and human experience and guides signers' but not speakers' attention to visual aspects of the world.

Bimodal bilinguals are hearing individuals fluent in a sign and a spoken language. Can the two languages influence each other in such individuals despite differences in the visual (sign) and vocal (speech) modalities of expression? We investigated cross-linguistic influences on bimodal bilinguals’ expression of spatial relations. Unlike spoken languages, sign uses iconic linguistic forms that resemble physical features of objects in a spatial relation and thus expresses specific semantic information. Hearing bimodal bilinguals ( n = 21) fluent in Dutch and Sign Language of the Netherlands and their hearing nonsigning and deaf signing peers ( n = 20 each) described left/right relations between two objects. Bimodal bilinguals expressed more specific information about physical features of objects in speech than nonsigners, showing influence from sign language. They also used fewer iconic signs with specific semantic information than deaf signers, demonstrating influence from speech. Bimodal bilinguals’ speech and signs are shaped by two languages from different modalities.

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We investigated cross-modal influences between speech and sign in hearing bimodal bilinguals, proficient in a spoken and a sign language, and its consequences on visual attention during message preparation using eye-tracking. We focused on spatial expressions in which sign languages, unlike spoken languages, have a modality-driven preference to mention grounds (big objects) prior to figures (smaller objects). We compared hearing bimodal bilinguals’ spatial expressions and visual attention in Dutch and Dutch Sign Language (N = 18) to those of their hearing non-signing (N = 20) and deaf signing peers (N = 18). In speech, hearing bimodal bilinguals expressed more ground-first descriptions and fixated grounds more than hearing non-signers, showing influence from sign. In sign, they used as many ground-first descriptions as deaf signers and fixated grounds equally often, demonstrating no influence from speech. Cross-linguistic influence of word order preference and visual attention in hearing bimodal bilinguals appears to be one-directional modulated by modality-driven differences.