Adults Who Stutter Don’t Stutter When They’re Alone

Summary: When alone, people who stutter tend not to be more fluent when talking. Researchers say the perception of being heard plays a key role in stuttering.

Source: NYU

The “talk-alone-effect”—the phenomenon in which people who stutter don’t stutter when they are alone—has been noted in anecdotal reports but until now, has not been supported by evidence.

A new study in the Journal of Fluency Disorders, led by NYU Steinhardt Professor Eric S. Jackson explores the talk-alone-effect among people who stutter, and how social pressure and the perception of a listener may influence speech. In the article, “Adults who stutter do not stutter during private speech,” the authors conclude that the talk-alone-effect is real and that the perception of being heard by a listener plays a key role in whether a person stutters.

“There is a lot of anecdotal evidence that people who stutter don’t stutter when talking alone, but this phenomenon has not been confirmed in the lab, mainly because it’s difficult to create conditions in which people believe that they are truly alone,” says Jackson.

The researchers evaluated 24 adults under five different conditions: conversational speech, reading aloud, private speech (in which participants were made to think no one was listening), repeating the private speech for two listeners, and spontaneous speech. With the exception of private speech, all conditions involved participants talking 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 deceived into thinking that nobody was listening to them, and were told that people who talk out loud to themselves are more likely to perform better on the task.

The private speech condition was the only condition in which instances of stuttering were non-existent.

The study, including the methods of deception, was approved by the Institutional Review Board at NYU. All participants were informed of the deception component after its conclusion and consented to continuing the experiment.

This shows a woman
The private speech condition was the only condition in which instances of stuttering were non-existent. Image is in the public domain

“We developed a novel method to convince participants that they are alone—that their speech wouldn’t be heard by a listener—and found that adult stutterers do not stutter under these conditions. I think this provides evidence that stuttering isn’t just a “speech” problem, but that at its core there must be a strong social component,” Jackson says.

According to Jackson, the presence or possibility of a listener introduces the possibility that the speaker will be evaluated socially. When a speaker is speaking privately, there is no social component, and therefore, the speaker is not concerned with perception or judgement.

The authors outline future directions for research on stuttering and suggest that examining private speech in young children would offer significant insight into the stages at which social considerations begin to influence stuttering.

In addition to Jackson, study authors include Lindsay Miller, a speech-language pathologist and NYU Steinhardt graduate; Haley Warner, a speech-language pathologist and doctoral student at NYU Steinhardt; and Michigan State University Professor J. Scott Yaruss.

Funding: This research was supported by a grant awarded to Jackson from the National Institute of Deafness and other Communication Disorders.

About this language research news

Author: Jade McClain
Source: NYU
Contact: Jade McClain – NYU
Image: The image is in the public domain

Original Research: Closed access.
Adults who stutter do not stutter during private speech” by Eric S. Jackson et al. Journal of Fluency Disorders


Adults who stutter do not stutter during private speech


Adults who stutter tend not to stutter when they are alone. This phenomenon is difficult to study because it is difficult to know whether participants perceive that they are truly alone and not being heard or observed. This may explain the presence of stuttering during previous studies in which stutterers spoke while they were alone. We addressed this issue by developing a paradigm that elicited private speech, or overt speech meant only for the speaker. We tested the hypothesis that adults do not stutter during private speech.


Twenty-four participants were audio-/video-recorded while speaking in several conditions: 1) conversational speech; 2) reading; 3) private speech, in which deception was used to increase the probability that participants produced speech intended for only themselves; 4) private speech+, for which real-time transcription was used so that participants produced the same words as in the private speech condition but while addressing two listeners; and 5) a second conversational speech condition.


Stuttering was not observed in more than 10,000 syllables produced during the private speech condition, except for seven possible, mild stuttering events exhibited by 3 of 24 participants. Stuttering frequency was similar for the remaining conditions.


Adults appear not to stutter during private speech, indicating that speakers’ perceptions of listeners, whether real or imagined, play a critical and likely necessary role in the manifestation of stuttering events. Future work should disentangle whether this is due to the removal of concerns about social evaluation or judgment, self-monitoring, or other communicative processes.

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