A short-acting psychedelic, 5-MeO-DMT, shifts speech from external focus to introspection. In 29 participants who kept daily voice journals two weeks before and after a single 12 mg dose, language analysis showed increased cognitive words and fewer social words, while vocal quality changed with more jitter and shimmer. Baseline speech patterns predicted how prepared people felt, the intensity of emotional breakthrough, and later well-being. This is the first longitudinal study showing that vocal journaling can track and predict psychological transformation around a psychedelic retreat, offering a framework for monitoring preparation and integration periods.
Psychotic symptoms such as hearing voices or feeling that thoughts are inserted may arise from failures in the brain's prediction and self-monitoring systems. Normally, when people talk internally, the brain sends copies of motor commands to auditory regions and suppresses them, helping distinguish self-generated from external input. When this suppression malfunctions, predicted inner speech can become perceptually salient and misattributed as external. Neuroimaging meta-analyses showed that psychosis-spectrum participants had increased activity in motor-related regions for inner speech and decreased grey matter in auditory cortices and anterior cingulate cortex. These regions form inversely coupled networks, supporting a hierarchical predictive-processing account where disruption distorts self-awareness.