Here’s how we can influence other people's decisions

A certain quality of your speech can help you convince others to do something.

A new University of Michigan study has explained how various speech characteristics influence people's decisions.

For the study, Jose Benki, a research investigator at the U-M Institute for Social Research (ISR) and colleagues used recordings of 1,380 introductory calls made by 100 male and female telephone interviewers at the U-M ISR.

They analysed the interviewers' speech rates, fluency, and pitch, and correlated those variables with their success in convincing people to participate in the survey.

"Interviewers who spoke moderately fast, at a rate of about 3.5 words per second, were much more successful at getting people to agree than either interviewers who talked very fast or very slowly," said Benki, a speech scientist.

But another finding from the study was counter-intuitive.

"We assumed that interviewers who sounded animated and lively, with a lot of variation in the pitch of their voices, would be more successful," said Benki.

"But in fact we found only a marginal effect of variation in pitch by interviewers on success rates. It could be that variation in pitch could be helpful for some interviewers but for others, too much pitch variation sounds artificial, like people are trying too hard. So it backfires and puts people off," he said.

Pitch, the highness or lowness of a voice, is a highly gendered quality of speech, influenced largely by body size and the corresponding size of the larynx, or voice box, he said.

Benki and colleagues Jessica Broome, Frederick Conrad, Robert Groves and Frauke Kreuter also examined whether pitch influenced survey participation decisions differently for male compared to female interviewers.

They found that males with higher-pitched voices had worse success than their deep-voiced colleagues. But they did not find any clear-cut evidence that pitch mattered for female interviewers.

The last speech characteristic the researchers examined for the study was the use of pauses. Here they found that interviewers who engaged in frequent short pauses were more successful than those who were perfectly fluent.

"When people are speaking, they naturally pause about 4 or 5 times a minute. These pauses might be silent, or filled, but that rate seems to sound the most natural in this context," Benki said.

"If interviewers made no pauses at all, they had the lowest success rates getting people to agree to do the survey. We think that's because they sound too scripted," he added.

The study was presented May 14 at the annual meeting of the American Association for Public Opinion Research.