Eye tracking based clustering using the Korean version of the reading the mind in the eyes test

This study applies eye-tracking paradigms to cluster data based on participants' gaze patterns, while performing the Korean version of the Reading the Mind in Eyes Test, and to investigate whether there were differences in the neurocognitive and other Theory of Mind (ToM) tests among the classified clusters. A total of 89 (50 males) non-clinical youths were recruited. The k-means algorithm was adopted, and the optimised number of clusters was determined using the elbow, silhouette and NbClust methods. Furthermore, multivariate analysis was employed to determine whether there were differences among the clusters in the neurocognitive and other ToM tests. Four clusters were proposed based on the index used to estimate the optimised cluster. The long word fixation time cluster had significantly more total errors and fewer categories completed in the Wisconsin Card Sorting Test, lower backward Digit Span score, and lower sequencing scores in the Theory of Mind Picture Stories Task than in the other clusters. The main findings suggested that even when performing a perceptual-level ToM task that requires the ability to understand mental states, at least in some individuals, gaze patterns are related to neurocognitive strategies, especially executive function, rather than to the specific social cognitive function itself.