Inefficient understanding of non-factive mental verbs with social aspect in adults: comparison to cognitive factive verb processing

INTRODUCTION: Mental verbs denote inner mental states and are an important link between language and Theory of Mind ability conceptualized as mental state understanding. Non-factive mental verbs denote an obligation or intention and constitute a discrete class of mental verbs which are characterized by their social aspect. This study aimed to examine adults’ ability to understand non-factive mental verbs with the social aspect as compared to cognitive factive mental verbs which denote a true event. METHODS: A total of 94 participants, aged 18–95 years, were examined using two tasks measuring non-factive and factive verb processing, respectively, and a working memory test. RESULTS: The results indicated that non-factive verbs process is at a significantly lower level than those of cognitive factives. CONCLUSION: The inspection of the way adapted to process the non-factive verbs denoting obligation or intention, as well as the confirmation of a unifactorial structure of the task developed to measure non-factives’ processing, showed that adults have a common pattern of non-factive mental verb understanding, which is based on heuristic ways of thinking and is not affected by working memory capacity and age.