I will present the results of a number of experiments on the role of audiovisual prosody for signalling and detecting meta-cognitive information in question-answering. The first study consists of an experiment in which participants are asked factual questions in a conversational setting, while they are being filmed. Statistical analyses bring to light that a speakers' confidence level is cued by a number of visual and verbal properties. Interestingly, it appears that answers tend to have a higher number of marked auditive and visual feature settings, including divergences of the neutral facial expression, when a speaker's confidence level is low, while the reverse is true for non-answers. The second study is a perception experiment, in which a selection of the utterances from the first study is presented to participants in one of three conditions: vision only, sound only or vision+sound. Results reveal that human observers can reliably distinguish high confidence responses from low confidence responses in all three conditions, be it that answers are easier than non-answers, and that a bimodal presentation of the stimuli is easier than the unimodal counterparts. The talk will end with some perspectives on related work about difference in the expression of confidence level between speakers who differ in age and cultural background.