Adaptations in humans for assessing physical strength from the voice

Adaptations in humans for assessing physical strength from the voice
Aaron Sell et al.; 2010
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2982226/


Abstract

Recent research has shown that humans, like many other animals, have a specialization for assessing fighting ability from visual cues. Because it is probable that the voice contains cues of strength and formidability that are not available visually, we predicted that selection has also equipped humans with the ability to estimate physical strength from the voice. We found that subjects accurately assessed upper-body strength in voices taken from eight samples across four distinct populations and language groups: the Tsimane of Bolivia, Andean herder-horticulturalists and United States and Romanian college students. Regardless of whether raters were told to assess height, weight, strength or fighting ability, they produced similar ratings that tracked upper-body strength independent of height and weight. Male voices were more accurately assessed than female voices, which is consistent with ethnographic data showing a greater tendency among males to engage in violent aggression. Raters extracted information about strength from the voice that was not supplied from visual cues, and were accurate with both familiar and unfamiliar languages. These results provide, to our knowledge, the first direct evidence that both men and women can accurately assess men's physical strength from the voice, and suggest that estimates of strength are used to assess fighting ability.

-------------------------------------------------------------------------------------------------------------

1. Average individual estimates of strength from the voice were accurate and highly significant across all six male samples ranging from γ = 0.18 to 31. This accuracy is similar to the accuracy of strength assessment from static visual images of the face, but lower than estimation from images of the body (Sell et al. 2009a).
2. Accuracy of strength estimation was similar across both familiar and unfamiliar languages.
3. While strength was accurately estimated from women's voices in both the US and Romanian samples, the effect was about half as large as for their male counterparts. The same pattern is found when assessing strength from visual images of the face (Sell et al. 2009a).
4. Estimates of strength were notably enhanced when both auditory and visual channels were available (see below).
5. Assessments of strength remained significant, controlling for both height and weight