Abstract: As an important metacognitive judgment, judgment of learning (JOL) is the prediction about future performance of learned materials. JOLs made during multiple study-test trials underestimate increases in recall performance across those trials, an effect that has been dubbed the underconfidence-with-practice (UWP) effect. Based on lots of experiment results, several theoretical explanations for UWP effect have been proposed, such as cue-utilization model, retrieval-fluency hypothesis, and anchoring-and-adjustment account. But, Koriat et al (2006) found these results did not point to a single mechanism that could account for the occurrence of the UWP effect, which suggesting that this effect might be multiply determined. Thus, they proposed a mnemonic debiasing account. The limitations of the precious studies and the suggestions for future research are put forward

Key words: judgment of learning, UWP effect, mechanism