Mental States Task (MST): Development, Validation, and Correlates of a Self-Report Measure of Mentalization


Please address correspondence to: Genevieve Beaulieu-Pelletier, Department of Psychology, University of Montreal, P. O. Box. 6128, Station Centre-ville, Montreal (Quebec), Canada, H3C 3J7. E-mail:



Mental states refer to the quality of one's capacity to mentally elaborate and open up to his or her subjective experience. The Mental States Task (MST) was developed to evaluate individual differences relative to this capacity.


Using the MST, participants described a story from an emotionally challenging image and responded to a set of items about their cognitive and emotional processes while completing the task. The validation of the French version of the MST comprises two samples: 264 undergraduate/graduate students with a mean age of 27.27 years (Sample 1), and 206 students with a mean age of 26.61 years (Sample 2). The validation of the English version of the MST also includes two samples: 110 undergraduate students with a mean age of 20.15 years (Sample 3) and 188 students with a mean age of 20.90 years (Sample 4).


Results suggest that 6 mental states can be distinguished and that the MST presents an adequate factorial structure, in both its French and English versions. The MST scores were associated with mental state scores derived from a content analysis method and with other related constructs (e.g., authenticity, empathy).


Overall, findings provide convincing evidence of validity and reliability for the MST as an assessment tool of mental states. This innovative measure is likely to facilitate the clinical and empirical investigation of mentalization.