Capturing naturalistic thoughts using a precision experience sampling idiographic approach.

The existing literature on naturalistic thoughts has offered insights into the general patterns of thoughts common across large groups of participants. However, little is known about individual variability in thoughts. One approach to understanding variation within individuals is precision experience sampling, an idiographic approach that involves sampling inner experiences across multiple sessions and/or timepoints. This creates a comprehensive portrayal of an individual's thoughts across time and context, which in turn facilitates person-specific predictions of their thoughts. The current study therefore used precision experience sampling to examine individual variations in naturalistic thoughts as a function of ongoing task. We implemented 7 sessions per participant (n = 7, idiographic group), resulting in 49 datasets. We verified that the descriptives of thoughts and task-modulatory effects of thoughts in this group were comparable to a larger cohort of participants (n = 49, nomothetic group) who each completed one session. Both groups were asked to complete whatever task they wished on the laboratory computer and to occasionally report their current task and numerous thought dimensions. Our results revealed considerable individual differences in the modulatory effects of task on thought dimensions, such that individuals engaged in different types of thoughts under different task contexts, underscoring the importance of considering both individual and contextual factors. They also indicated that patterns observed at the group level did not always accurately represent individual level patterns. Furthermore, applying machine learning algorithms on reports of the task-at-hand reliably detected all thought dimensions, with superior classification performance in the idiographic compared to nomothetic group. Overall, our study demonstrates the idiosyncratic effects of task on naturalistic thoughts and highlights the value of precision experience sampling in improving person-specific predictions of thoughts, which has important methodological and clinical implications.