Iconicity in Spatial Language Guides Visual Attention: A Comparison Between Signers' and Speakers' Eye Gaze During Message Preparation

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.