Abstract: Two essential ingredients of everyday cognition are the ability to reason counterfactually and the ability to understand and predict other people¢s behaviour by attributing independent mental states to them (theory of mind). Theory of mind gradually became one of the areas of much interest among developmental psychology and cognitive neuroscience. In everyday life, people interact in a variety of ways – playfully, competitively, cooperatively – and by their very nature, interactions are more conceptually and methodologically difficult to study than the behaviour and experience of a single person. Understanding the interactive mind is more complex than understanding the single-person mind.
Using three types of Chinese four-character idioms—‘physical idioms’, ‘single person idioms’ and ‘interactive idioms’, the present study was designed to explore the dissociative electrophysiological correlates between reading another’s mind and reading the interactive mind. We report one eye-movement study (Experiment 1) and one ERP study (Experiment 2) investigating time course of reading another’s mind and reading the interactive mind.
Results from Experiment 1 showed that the total reading times of the second character in single person idioms were longer than in physical idioms. Furthermore, the gaze durations of the first three characters in interactive idioms were longer than in both physical idioms and single person idioms. Results from Experiment 2 showed that in the 500-700ms epoch, the mean amplitudes of the late positive component (LPC) over frontal for single person idioms and interactive idioms were significantly more positive than for physical idioms, while there was no difference between the former two. In the 700-800ms epoch, the mean amplitudes of the LPC over frontal-central for interactive idioms were more positive than for single person idioms and physical idioms, while there was no difference between the latter two.
Our data provide a direct comparison between the electrophysiological correlates for reading another’s mind as well as reading the interactive mind. Our findings show that reading the interactive mind overlaps the neural system capable of reading another’s mind but requires the involvement of an additional system. Individuals first are able to read another’s mind, and the reading the interactive mind builds on that earlier understanding by involving the same mental-state processing characteristic of reading another’s mind plus an additional interactive mind processing system as well. We believe that reading another’s mind and reading the interactive mind are two different levels of theory of mind. Reading another’s mind is the basis for reading the interactive mind and the level of reading the interactive mind is higher than the level of reading another’s mind.

Key words: theory of mind, mind-reading, eye movement, ERP, Chinese idiom