**3. Neurophysiological studies on vocal sarcasm, sincerity and confidence**

In order to evaluate whether and how basic emotional and higher‐level social information (e.g., attitudinal) are manifested in the brain in a different manner, Wickens and Perry [13] compared the ERP responses to neutral, angry, and sarcastic expressions. These expres‐ sions began with a leading phrase (e.g., He has) in a neutral voice and were followed by an expression (e.g., a serious face) intoned with different voices. As compared with the neutral expression, both angry and sarcastic expression elicited an increased P200 and a late positiv‐ ity effect (450–700 ms) with no amplitude difference between the two emotions. The angry voice also elicited an early N100 as compared with the other two expressions when listeners performed a probe‐verification task. These findings revealed similar neurocognitive pro‐ cesses between basic emotion and interpersonal attitudes conveyed in the voice while the basic emotion seems to be registered earlier under certain conditions. Other studies revealed that the decoding of sarcasm involved similar neurocognitive processes to social intention perception. Rigoulot et al. [14] compared compliments with sincere vs. insincere tone of voice (What do you think of my presentation? I think it is very interesting) and found that the sincere compliment to the question elicited a larger P600 effect as compared with the insincere one. This ERP effect was localized in the left insula which is associated with the action of lying and concealment.

Recent growing evidence has been accumulated in the field of decoding of speaker's feeling of (un)knowing using event‐related potentials. In Jiang and Pell [15], vocal expression of con‐ fidence was manipulated such that statements which sounded very confident, somewhat con‐ fident, and unconfident and those which sounded neutral were presented to native English speakers. At the onset of the vocal expression, the confident expression elicited an increased positive response than the other two types of expressions. The unconfident expression elicited an increased P300 as compared with the confident and the neutral expression. The neutral voice produced a more‐delayed positivity as compared with all confidence‐intending expressions.

Two follow‐up experiments further evaluated how the decoding of vocal confidence expres‐ sion is impacted by the presence of additional linguistic cues which either congruent [16] or incongruent [17] with the tone of voice in statements which followed the linguistic cues. Different from the statements with no lexical cues, statements with congruent cues (e.g., I'm sure; Maybe) elicited an increased N1 and P2 for confident than for unconfident and close‐to‐ confident expressions, and an enhanced delayed positivity in unconfident and close‐to‐con‐ fident expression than confident one. Moreover, the direct comparison between statements with and without a preceding lexical phrase elicited a reduced N1, P2, and N400 in those without a phrase [16]. The incongruent cues elicited different ERP effects at the onset of the main statement of confident and unconfident tones. The unconfident statement elicited an increased N400 or late positivity (depending on the listener's gender). The confident state‐ ment elicited a more delayed, sustained positivity effect. Source localization of these ERP effects revealed pre‐SMA for N400, suggesting a difficulty in accessing the speaker mean‐ ing, and SFG, STG and insula underlying the late positivity effect, suggesting an increased demand of executive control to implement the attentional resources and socioevaluative pro‐ cesses [17]. These studies extended the neurocognitive model for basic vocal emotion and argued for a perspective of studying the neurophysiological mechanisms underlying decod‐ ing interpersonal and sociointeractive affective voice.
