Probing the effect of perceptual (dis)fluency on metacognitive judgments.

Despite research showing that perceptually fluent stimuli (i.e., stimuli that are easier to process) are given higher judgment of learning (JOL) ratings than perceptually disfluent stimuli, it remains unknown whether the influence of perceptual fluency on JOLs is driven by the fluent or disfluent items. Moreover, it is unclear whether this difference hinges on relative differences in fluency. The current study addressed these unanswered questions by employing (Fiacconi et al., Journal of Experimental Psychology: Learning, Memory, and Cognition 46:926-944, 2020), Journal of Experimental Psychology: Learning, Memory, and Cognition, 46[5], 926-944) letter set priming procedure. In this procedure, participants are first exposed to words containing only a subset of letters. Following this exposure, JOLs to new words composed of the same letters (i.e., fluent), and new words composed of nonexposed letters (i.e., disfluent) are compared with isolate the contribution of perceptual fluency. Because this procedure does not rely on parametric variations in perceptual features, we can directly assess the potential benefit and/or cost of fluent and disfluent items, respectively, by including neutral baseline conditions. Moreover, implementing both a mixed- and pure-list design allowed us to assess the comparative nature of perceptual fluency on JOLs. Counter to previous assumptions, our results are the first to demonstrate that perceptual disfluency decreases JOLs. Moreover, we found that the influence of perceptual disfluency on JOLs hinges on the relative differences in fluency between items even in the absence of a belief about the mnemonic impact of the fluency manipulation. These findings have important implications as they provide evidence that the difficulty, rather than ease, of information form the basis of individuals metacognitive judgments.