Combining paralinguistic and linguistic functions of eyebrows in NGT: A matter of phonetic force

In Sign Language of the Netherlands (Nederlandse Gebarentaal/NGT) the eyebrows are used for syntactic functions. In yes-no questions the eyebrows are raised, while in wh-questions the eyebrows are frowned (Coerts, 1992). What is more, these same brow positions are associated with expression of surprise and anger. In this study sentences were elicited that combine both functions. Brow positions were analysed using the Facial Action Coding System by Ekman (2002). This system allows for the differentiation of three Action Units involving the brows that can be combined in any logically possible way: AU 1 Inner Brow Raiser, AU 2 Outer bro raiser, and AU 4 Brow lowerer. Although it was hypothesised that affective functions of eyebrows would dominate the syntactic functions, it was found that the phonetic force of AU 4 plays an important role