Emma Young, BPS Research Digest.
How do you know whether to trust what someone is telling you? There’s ongoing debate about which cues are reliable, and how good we are at recognising deception. But now a new paper in Nature Communications reveals that we reliably take a particular pattern of speech pitch, loudness and duration as indicating either that the person lying or that they’re unsure of what they’re saying — and that we do it without even being aware of what we’re tuning into.
In an initial study, Louise Goupil at Sorbonne University, France, and her team manipulated the pitch, loudness and duration of a series of spoken pseudo-words (which sounded like they could be real words in French, but were not). Twenty native French speakers then listened to these words and rated the speaker’s honesty and also their certainty (honesty and certainty were investigated in two separate trials with the same participants, held one week apart). The participants were also asked how confident they were in their judgements.
The team’s analysis revealed that a single “prosodic signature” — that is, the same pattern of volume, pitch, and speed — was associated with perceptions of both honesty and certainty. Loudness (especially at the beginning of the word), a lower pitch towards the end of the word, a less variable pitch overall, and a faster pace of speaking were all associated with more honesty/confidence. The opposite patterns were associated with less of either. The team also found that the participants were more confident when making judgements about the speaker’s certainty.