Neural correlates of inferring speaker sincerity from white lies: An event-related potential source localization study

• We investigated what brain processes allow to detect the sincerity of compliments.
• Speech prosody is used to discern the intended sincerity of compliments.
• P600 amplitudes are greater in response to sincere versus insincere compliments.
• Anatomical sources of this P600 effect are located in the insula.
• These data shed new light on brain processes involved during social communication.

During social interactions, listeners weigh the importance of linguistic and extra-linguistic speech cues (prosody) to infer the true intentions of the speaker in reference to what is actually said. In this study, we investigated what brain processes allow listeners to detect when a spoken compliment is meant to be sincere (true compliment) or not (“white lie”). Electroencephalograms of 29 participants were recorded while they listened to Question–Response pairs, where the response was expressed in either a sincere or insincere tone (e.g., “So, what did you think of my presentation?”/“I found it really interesting.”). Participants judged whether the response was sincere or not. Behavioral results showed that prosody could be effectively used to discern the intended sincerity of compliments. Analysis of temporal and spatial characteristics of event-related potentials (P200, N400, P600) uncovered significant effects of prosody on P600 amplitudes, which were greater in response to sincere versus insincere compliments. Using low resolution brain electromagnetic tomography (LORETA), we determined that the anatomical sources of this activity were likely located in the (left) insula, consistent with previous reports of insular activity in the perception of lies and concealments. These data extend knowledge of the neurocognitive mechanisms that permit context-appropriate inferences about speaker feelings and intentions during interpersonal communication.