The University of Bath has conducted a study: K.Maras et al, “Eyewitness testimony by individuals who stammer: Evidence, experience and perceived credibility”, https://doi.org/10.1111/bjop.70014
Very briefly, some points from the study:
- People who stammer recalled as much correct information as non-stammering witnesses overall, though less during free recall, as opposed to when probed with follow-up questions (cued recall).
- People who stammer reported a “cyclical interplay between communicative pressure, anxiety over listener misperceptions and stammer severity, which they navigated by prioritizing either fluency or testimony content”. So some used avoidance techniques such as switching words and limiting speech etc, while others spoke though their stammer.
- Mock jurors watched video recordings of interviews with witnesses. They rated witnesses with a stammer as less confident, yet more likeable and trustworthy than non-stammering witnesses. Providing jurors with information about stammering further improved their likeability and trustworthiness, but had no impact on perceived confidence.
- The study says: “Participants [who stammer] called for increased awareness and education within the [Criminal Justice System] to challenge stereotypes and mitigate prejudices that may impact listener perceptions. They also suggested that alternative mediums of testimony should be offered, such as video conferencing, written statements and pre-recorded testimony at court, to enhance accessibility and reduce anxiety around listener perceptions…, and that familiarization with the judge and courtroom would be particularly beneficial at trial.”
It should be noted that this study was not of witnesses speaking in a courtroom setting, or in a group setting. Each witness was interviewed by one person via online video. Recordings were later watched by mock jurors individually.
As the study also acknowledges, under Limitations, the interviewer knew of the person’s stammer, so the person may have been less worried about their listener’s reaction. Furthermore, there was a high chance of selection bias in the people who stammer taking part, since “the people who volunteered to participate were likely at a specific point with their stammer where they felt confident to do so”.
STAMMA (formerly the British Stammering Association) have said – in their November 2025 AGM – that a guide for lawyers working with witnesses and defendants who stammer is to be published shortly by The Advocates Gateway.
I’m currently working on updating my page Appearing in court with a stammer, including Appearing in court with a stammer>Mistaking stammering for dishonesty.
