Biased polar question forms in Sign Language of the Netherlands (NGT)

We identify several polar question forms in Sign Language of the Netherlands (NGT)through a production experiment in which we manipulate two types of biases: (i) theprior expectations of the person asking the question, and (ii) the evidence available inthe immediate context of utterance. Our analysis in the present paper focuses on formsinvolving headshake. We find that in some cases headshake expresses negation, as expected,but in other cases it fulfils another function, namely, it is part of a sentence-finalphrase either expressing uncertainty or signalling a request for a response from the addressee,or possibly both at the same time. We further observe that each question formhas a distinct ‘bias profile’, indicating a certain combination of prior expectations andcontextual evidence. Besides these empirical findings, our study also makes a methodologicalcontribution: our experimental design could be used in future work to identifypolar question forms with different bias profiles in sign languages other than NGT, aswell as visual cues accompanying polar questions with different bias profiles in spokenlanguages.