A house of cards: bias in perception of body size mediates the relationship between voice pitch and perceptions of dominance

Theories of the evolution of low voice pitch in men are based on the idea that voice pitch is an honest indicator of physical dominance, but relationships among pitch, physical body size and strength among same-sex adults' voices are weak and unstable. Nevertheless, judgements of body size based on voice pitch are the result of perceptual bias that low frequencies sound large. If dominance judgements are based in part on perception of size, then dominance perception could also be the result of perceptual bias. Thus, we tested whether the relationship between voice pitch and judgements of height mediate the relationship between voice pitch and dominance judgements. The relationship between voice pitch and perceived height fully mediated the relationship between voice pitch and dominance. This was driven by the portion of variance that was inaccurate in height perception (i.e. residual error), and not conditional upon actual height, or perceptions thereof. Collectively our results demonstrate that the relationship between voice pitch and perceived dominance is not based on observation of real-world relationships between physical size and voice pitch, but rather based on a bias to perceive low-pitched voices as large people. Hence, the relationship between dominance and voice pitch is coincidental rather than causal. Thus, since the relationship between physical dominance and voice pitch is conditional upon the relationship between a biased perception of body size, voice pitch is not an honest indicator of physical dominance. Consequently, the evolution of low pitch in men's voices cannot be explained by selection for accurate dominance cues.