Measures of individual differences in adult theory of mind: A systematic review.

Theory of mind (ToM), the ability to understand and reason about mental states, has been extensively studied in young children and clinical populations. A growing interest in examining ToM in adults has emerged over the past two decades, but the extent to which existing measures are suitable for studying adults, especially in detecting individual differences, remains understudied. In this systematic review of 273 studies, 75 measures used to investigate individual differences in adults' ToM were identified. Their sensitivity to individual differences, reliability, and validity were examined. Results suggest that ceiling effects were prevalent, and there was limited evidence to establish the reliability or validity of these measures due to the lack of reports of psychometric properties. Interrelations among measures were inconsistent. These findings highlight the need for future empirical and theoretical work to broaden the evidence base regarding psychometric properties of measures, to develop new measures, and to lay out more specific hypotheses about the relevance of ToM for different social outcomes.