Eyewitness testimony by individuals who stammer: Evidence, experience and perceived credibility.

Stammering may impede an individual's eyewitness testimony and reduce jurors' perceptions of their credibility through a complex interplay of bio-psycho-social factors. However, no research to date has explored this. Three co-produced, mixed-methods studies are reported, investigating the evidential quality, lived experiences and perceived credibility of people who stammer (PWS) as witnesses. In pre-registered Study 1, PWS recalled as much correct information as non-stammering witnesses overall. However, during the free - but not cued - recall interview phase, PWS provided fewer correct details. A reflexive thematic analysis of participants' post-testimony reflections captured how PWS experienced a cyclical relationship between communicative pressure, anxiety over listener misperceptions and stammer severity, which they navigated either by employing avoidance strategies at the expense of testimony or by speaking through their stammer. In pre-registered Study 2, mock jurors rated PWS as less confident yet more likeable and trustworthy than non-stammering witnesses. In Study 3, providing jurors with information about stammering further improved their likeability and trustworthiness but had no impact on perceived confidence. Findings provide new insight into communication disorders in legal contexts - and the unique challenges faced by PWS in particular - demonstrating the need for systemic accommodations and targeted training for legal professionals.