**Discussion**: * Most people rely more on their left hemisphere than their right to use language * We looked at data obtained across different language and speech tasks: overt sentence reading, overt picture description, covert sentence reading, and covert auditory naming. Overt speech refers to audible production of words/sentences, while covert speech refers to imagined speech (silent production of words/sentences with no articulation) * Main findings: (1) there was no evidence in support of the idea that PWS are differently lateralized relative to people who are typically fluent and some anecdotal and moderate evidence in support of the idea that they are equally lateralized; (2) leftwards lateralization was most robustly observed for the covert tasks relative to the overt tasks and this effect was seen in both groups. * No Differences in Laterality between PWS and TFS * We find no support for the idea that PWS are more likely to be left-handed than typically fluent speakers, nor that their handedness alters the typical pattern of left-hemispheric cerebral dominance for speech and language. * In our main findings, we found that PWS and TFS show equivalent levels of language lateralization across a range of tasks. * The authors reported that the language was mostly left lateralised in both groups over frontal, temporal and parietal regions without significant differences between groups. * On the other hand, several studies reported additional right hemisphere activity in PWS compared with controls during speech production (Kell et al., 2009; Neef et al., 2018; Neumann et al., 2005) and this right hemisphere overactivity in the inferior frontal cortex or frontal operculum was described as one of the neurophysiological “signatures” of stuttering (Brown et al., 2005). * This overactivity was interpreted as an overly active global response suppression mechanism mediated via the hyper-direct pathway to the subthalamic nucleus rather than reflecting reorganisation of function to the right hemisphere or compensatory recruitment of right hemisphere homologues of left hemisphere speech areas. Since this overactivity in the right hemisphere remains during both covert speech and covert humming conditions, it may not reflect reduced left-lateralised activity for language functions but instead an inhibitory response present in adults who stutter. * On the other hand, it has been reported that certain therapeutic interventions for stuttering have demonstrated the potential to enhance neural activity within the left hemisphere of the brain (Toyomura et al., 2015) or shift the balance of activity from the right hemisphere to the left during speech production (Kell et al., 2009; Neumann et al., 2005). * However, neither of these studies statistically compared the activity between two hemispheres in PWS and controls, which may explain why our results differ from these previous studies that we did not find a difference in laterality. * Reasons for overactivation in one hemisphere: inhibition, compensation or error responses, statistical thresholding (giving the impression that there is no activity in one hemisphere because it is only visible sub-threshold) * *LIs are More Strongly Left Lateralised for the Covert Tasks* * In our findings, covert language tasks were significantly more lateralised compared with overt tasks. Reasons: * The reason may be that the cortical motor areas that send hundreds of commands to dozens of muscles bilaterally during overt speech production are not involved in covert speech. When the motor cortex is heavily involved in overt articulation, perhaps this bilateral pattern of task-related activity reduces laterality measured by methods that include these areas. * Both tasks (covert sentence reading and auditory naming) involved continuous data acquisition during imaging. In contrast, the overt speech production tasks were carried out using sparse sampling to allow participants to hear themselves * With our current datasets, we cannot disentangle possible causes of our finding that covert tasks were more strongly lateralized than overt ones since this factor is confounded with the measurement difference