Abstract:

Previous social neuroscience studies focused mainly on the neural networks that sustain an understanding of a single individual’s neutral or negative intentions. However, few studies have explored those of different types of social interactive intentions performed by two or a number of individuals and their whole body movements. In addition, the spatio-temporal dynamics of understanding the kind and hostile intentions in the human brain also remain unclear.
In order to address the above issue, the electroencephalograph (EEG) technique was employed to explore the dissociative neural correlates of understanding kind versus hostile intention. Twenty healthy participants were recruited for the experiment. Their behavioral data (accuracy and reaction time) and electrical brain activities were recorded while they were watching colorful photos depicting two actors’ actions and performing an intention inference task (IIT). There were three different types of action intentions: kindness, hostility and non-interactiveness (neutrality). The ERP data was analyzed using the Scan and sLoreta software in an off-line way.
The Univariate Analysis of Variance (ANOVA) with repeated measures of mean accuracy showed no significant difference among three conditions, while a main effect of condition existed for reaction time. The reaction times of hostile intention were shorter than those of the kind and neutral intentions, while no significant difference was found between the latter two conditions. The ERP data were analyzed using a three-way repeated measure ANOVA. The ANOVA factors were intention condition (kindness, hostility and neutrality), laterality (left, midline and right areas) and caudality (frontal, central and parietal areas). Electrophysiological results showed, over the frontal area, a significantly more negative amplitude of N250 (170~270 ms) for neutral intention compared to kind and hostile intentions, and the N250 amplitudes for kind intention were also more negative than those for hostile intention, especially on the FZ electrode site. The source localization showed maximum activation in Broadman 10 (BA10), in the vicinity of middle frontal gyrus, for N250 for kind and hostile intentions. At the later stage (270~450 ms), the peak amplitudes of the P300 for hostile intention were more positive than those for the kind and neutral intentions, and the P300 amplitudes for kind intention were also more positive than those for neutral intention over the central, parietal areas as well as the right hemisphere. The maximum activation for P300 of kind and hostile intentions was found in BA45, located in the vicinity of insula, and a stronger activity existed for hostile intention compared to kind intention.
These findings show that there is a spatio-temporal dynamic dissociation between kind and hostile intentions understanding in the brain. Altogether, the current study provides electrophysiological evidence underlying the kind, hostile interactive intentions and non-interactive (neutral) intention understanding, and suggests a prioritized and sustained processing for hostile interactive intention. The study enriches the contents of the two-stage intention-understanding model and the putative Hierarchical & Multi-level Cognitive Framework (HMCF) in Theory of Mind.

Key words: Theory of Mind, kind intention, hostile intention, dyadic interaction, ERP