"You don't know what this means to me" - Uncovering idiosyncratic influences on metamemory judgments.

Studies of the mind often focus on general effects on cognitive processes, whereas influences of idiosyncratic interactions between participants and items evade experimental control or assessment. For instance, assessments of one's own learning and memory processes-metamemory judgments-are attributed to people's reliance on commonly shared characteristics of study materials (e.g., word frequency) or learning conditions (e.g., number of study opportunities). By contrast, few studies have investigated how idiosyncratic information such as the personal significance of items affects memory and metamemory. We propose that hitherto elusive idiosyncratic influences on metamemory can be measured by the C component of Egon Brunswik's (1952) lens model. In two experiments, we made randomly chosen items personally significant (Experiment 1) or assessed the personal significance of items (Experiment 2). Personal significance increased both metamemory judgments and memory performance. Including personal significance as a predictor in the lens model reduced C, whereas including familiarity from a previous encounter did not. Hence, at least part of the lens model's C parameter captures idiosyncratic influences on metamemory. The C parameter may serve as a useful tool for future research.