“…The first relates to manual aspects of sign language, including clarity of signs/fingerspelling (e.g., hand shape, movement, placement, and orientation), appropriateness of vocabulary and register (e.g., specialized terminology, language style), and correctness of grammar and structure (e.g., grammaticality, use of space, classifiers, tenses, indexing) (see Bontempo & Hutchinson, 2011;Russell & Malcolm, 2009;Strong & Rudser, 1985;Wang et al, 2015). The second relates to non-manual aspects of sign language (i.e., non-manual markers/ signals), including mouthing, eye gazing, facial expressions, body shifting, and head tilting (Bontempo & Hutchinson, 2011;De Wit & Sluis, 2014;Russell & Malcolm, 2009;Wang et al, 2015). These non-manual markers/signals are important in sign language, as they are used to modify verbs, adjectives, and other adverbs, and also to convey grammatical information such as constructed dialogue and sentence types (e.g., wh-question).…”