Humans use a wide range of cues, both verbal and non-verbal, to communicate different emotions.

But vocalizing some positive emotions may be a socially learned behavior, as opposed to a product of evolution, according to a new study in PNAS that looked at non-verbal emotional vocalizations in two different cultural groups.

For the study, University College London researchers  compared the responses of 51 Westerners to those of 58 remote and culturally isolated semi-nomadic Himba people of Namibia. Nine emotions - achievement, amusement, anger, disgust, fear, sensual pleasure, relief, sadness, and surprise - were recorded from vocal signals of speakers belonging to both groups and used to test the study participants.

Participants listened to several short stories in their native languages and were then asked to identify which of two emotional vocalizations matched the sentiment of each story.

Researchers discovered that vocalizations expressing the six basic emotions - anger, disgust, fear, joy, sadness, and surprise - were recognized by both groups, indicating that they, like facial expressions, are universally evolved functions.

When an additional set of positive emotions was introduced - achievement, sensual pleasure and relief - they were only reliably recognized by the Western subjects.

The findings suggest that vocal signals are "a universal signal of emotion and extend models of cross-cultural communication of emotional signals to nonverbal vocalizations," according to the Faculty of 1000 Medicine review of the study. Furthermore, "
vocal signals can be modulated by culture-specific variation with some positive affective states not shared across cultures," the review explains.

Citation: Sauter et al., 'Cross-cultural recognition of basic emotions through nonverbal emotional vocalizations', Proc Natl Acad Sci, February 2010, 107(6), 2408-12

Faculty of 1000 Medicine study evaluation