People in the early stages of psychosis show a reduced ability to accurately evaluate their own perceptions, a metacognitive deficit. In a perceptual decision-making task, individuals with first-episode psychosis performed worse on metacognitive accuracy than healthy controls, even when their basic perceptual performance was accounted for. Grey matter volume was also reduced in the superior frontal gyrus, a brain region linked to metacognition. However, no direct relationship was found between grey matter volume and metacognitive accuracy, leaving the neural basis of this deficit unclear. These findings suggest that a specific problem in scrutinizing one's own perceptions may underlie later functional difficulties in schizophrenia.
Repeated recreational use of MDMA (Ecstasy) is linked to lasting impairments in explicit memory. In this study, 15 abstinent MDMA users and 17 matched controls completed tests of memory and vocabulary. MDMA users showed deficits in episodic prospective memory—remembering to perform future tasks—with medium to large differences on time-based and event-based subtests. The ability to recall a future appointment appeared related to how often and how many times MDMA had been used. Further research is needed to explore the neurological basis of these deficits, particularly the role of serotonin.
In non-clinical groups, unusual sensory experiences like those in Tulpamancy and ASMR communities are not linked to stronger metacognitive beliefs, but having multiple such experiences is associated with higher hallucination-proneness. Tulpamancers who also experience ASMR scored higher on hallucination-proneness than controls, while Tulpamancers reported lower endorsement of metacognitive beliefs. No differences emerged in delusion-proneness, self-reflection, or self-schemas across groups. Metacognition influences unusual experiences in non-clinical populations, and the relationship varies by group. Improving metacognition in clinical populations may help reduce distress tied to unusual sensory experiences.