Emotional and non-emotional mental imagery and auditory verbal hallucinations (hearing voices): A systematic review of imagery assessment tools

It is still unknown whether auditory verbal hallucinations (AVHs) and mental imagery are similar or distinct concepts. In order to determine this, we need appropriate assessment tools to measure mental imagery in people with AVHs. Trials evaluating this used both emotional and non-emotional mental imagery measures. This has complicated comparing outcomes and evaluating the relationship between AVHs and mental imagery. Therefore, this study aimed to review the literature on mental imagery in individuals with AVHs regarding 1) imagery assessment tools used in this population, 2) emotional and non-emotional mental imagery in relation to AVHs, 3) to develop a model of different mental imagery domains and related assessment tools. We conducted a systematic literature search in the PubMed Database and after full-text screening, 16 papers were included. We found that various assessments methods are used to assess different aspects of mental imagery, suggesting that there is a lack of agreed theoretical conceptualisation of mental imagery and AVHs. In addition, the studies showed that non-emotional mental imagery did not seem related to AVHs, while emotional mental imagery was related to AVHs. Lastly, we proposed a new model of mental imagery domains and corresponding assessment methods distinguishing between emotional and non-emotional mental imagery.