A listener’s perception of being heard plays a key role in whether a person stutters, a new study led by NYU Steinhardt Professor Eric S. Jackson reveals.
The phenomenon in which people who stutter do not stutter when alone has been observed in anecdotal reports, but has not been supported by evidence so far .
Five different conditions
The researchers tested 24 adults under five different conditions: conversational speech, reading aloud, private speech (in which participants were made to think that no one was listening), repeating private speech for two listeners, and spontaneous speech. With the exception of private speech, all conditions involved participants speaking or reading to others .

In the private speech condition, participants were left alone to complete a challenging computer programming task, which has been shown to elicit private speech in previous studies.
Participants were also tricked into thinking that no one was listening, and were told that people who spoke aloud to themselves were more likely to perform better on the task.
The private speech condition was the only condition in which there were no cases of stuttering .