Revisiting the Plausibility Effect in Remembering Truth and Falsity: An Analysis of Underlying Memory and Guessing Processes

Plausibility seems to play a key role in how well people remember the veracity of information. In a study by Vorms and colleagues (2022), an interaction pattern between statement plausibility and veracity feedback on memory performance appeared: Plausible statements were significantly more often correctly identified as true than correctly identified as false; for implausible statements, the descriptive trend was reversed. Given the importance of accurate memory for truth and falsity in real-world settings, it is crucial to understand the cognitive processes underlying this plausibility effect. For this purpose, we conducted a preregistered experiment in which participants studied four different statement types along with veracity feedback: plausible true, plausible false, implausible true, and implausible false. In a later recognition test, they indicated whether a statement was presented and, if so, what veracity feedback was displayed. We replicated the plausibility effect as an interaction between statement plausibility and veracity feedback on correct true/false attributions. Moreover, we analysed the data with a multinomial model to estimate the contribution of statement memory, feedback memory, and different guessing processes underlying the observable responses. These analyses revealed that guessing processes and statement memory accounted for the above-mentioned plausibility effect: Feedback guessing was influenced by corresponding statement plausibility, and statement memory was overall better when the veracity feedback aligned with statement plausibility. In contrast, feedback memory was enhanced in the case of a discrepancy between veracity feedback and statement plausibility. These results emphasise the importance of examining the processes driving the plausibility effect to derive correct conclusions.