States of mind: Towards a common classification of mental states

Thanks to the wealth of studies on mind-wandering, the stream of thought has now become, again, the focus of mainstream investigations in cognitive psychology. Yet, how one should describe and measure the stream of thought is still very much left undecided. Here, we approach the problem through the notion of mental states. Based on conceptual analysis and previous empirical data, we identify five states: focus, task-related interference, external distraction, daydream, and blank. We ask the question whether this classification (the Classification of Mental States − CoMS-5T) − provides an adequate partition of mental states. To do so, first, we rely on participants’ free verbal reports of their mental contents, that were then classified off-line by external raters. We provide evidence for the construct validity of the CoMS-5T and for its neutrality, in the sense that it does bias participants’ reports. Second, we provide evidence for the criterion validity of the CoMS-5T: by means of a reanalysis of a large data set made available by Beikmohamadi and Meier (2022), we find distinct behavioural signatures for four of the five states in the CoMS.