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.

Children and monkeys overestimate the size of high-contrast stimuli

The letter height superiority effect reveals that human adults judge letters to be taller than identically sized pseudoletters. This effect extends to words, such that words are estimated to be greater in size or lasting longer in duration than pseudowords of the same size or those presented for the same duration. The physical properties of letters and words also impact their perceived size, such that higher contrast between figure-ground stimuli leads to greater size estimates. Specifically, black letters on a white background (high contrast between figure and ground) are judged to be taller than gray letters and gray pseudoletters on a white background (low contrast between figure and ground) for adult humans. In the current study, we assessed whether this effect would extend to nonverbal stimuli (shapes) such that high-contrast shapes would lead to greater size estimates relative to low-contrast shapes for human children and rhesus monkeys in a two-choice discrimination task. We found that children and monkeys tended to overestimate the size of high-contrast shapes relative to low-contrast shapes consistent with results reported among human adults. Implications for perceptual fluency and its impact on subjective size estimates are discussed.