Animal vocal signals contain information about the signaler, such as motivation or ability to defend resources, overall health, or genetic quality. Signal receivers attend to the information contained in these signals and use it to adjust their own behavior. For example, our research with songbirds shows that song amplitude (i.e., “loudness”) reliably signals the likelihood of attack. While human language is unique and more complex than the communication systems of animals such as songbirds, we too are influenced by non-verbal aspects of speech. That is, listeners are affected by both the words that we say, and how we say them. Relevant to the current election season, our research shows that vocal traits can influence how we select our leaders.

We became interested in studying the influence of candidates’ voices on voters when we discovered the growing literature on human voice pitch. Many studies show that the “highness” or “lowness” of a person’s voice affects how they are perceived and treated by others. For example, men with lower voices are perceived as more dominant and more attractive. Women with lower voices are also perceived as more dominant, but women with higher voices are perceived as more attractive.

Given our shared interests in vocal signaling and politics we decided to test whether candidate voice pitch also influences voter behavior. Our first study on this subject was based on a series of experiments in which participants selected between hypothetical candidates with higher- and lower-pitched voices. The results showed that both male and female voters prefer male and female candidates with lower sounding voices.

To investigate why voters prefer leaders with lower voices we conducted another experiment in which we again asked participants to vote between hypothetical candidates with lower or higher sounding voices. We also asked them which voice of each pair they perceived as sounding stronger, more competent, and older. We found that each of these perceptions explains some of the preference for candidates with lower voices, but perceptions of competence and strength mattered significantly more to our voters than did a candidate’s age. In other words, these data suggest that we are more likely to vote for candidates with lower voices largely because we see them as stronger and more competent, and to a lesser degree because we perceive them as older and more experienced.

Our findings led to the obvious question of whether they would hold up in the real world. In a study of the 2012 U.S. House elections we found that male and female candidates with lower voices were indeed more likely to win. We also were able to demonstrate that these results hold up even if we account for alternative explanations of electoral outcomes, such as campaign spending, incumbency (i.e., whether the candidates currently held office), candidate sex, and the ideological preferences of voters.

It remains unclear whether our bias in favor of candidates with lower voices influences us to select better leaders. What is very clear, however, is that this bias impacts our decisions at the polls. To be clear, our perceptions of a candidate’s voice are unlikely to override our opinions on policy, partisanship, and all of the other myriad influences on electoral outcomes. The crucial point, however, is that elections are often won on the narrowest of margins, and so it is conceivable that these thin, impressionistic judgments can and do impact who we choose to govern us. As you listen to the candidates stump this election season, think about how you are judging them. Is the tone of their voice impacting your perceptions of their ability to lead our country?