Metacognition has been defined as the ability to evaluate our own cognitive activity. While the influence of emotions on cognition has largely been examined, little is known so far about how emotional states impact metacognitive processes. Evidence has suggested that reported confidence levels may be influenced by emotion; however, the underlying behavioral and neural mechanisms of such influence on metacognitive functions remain poorly understood. To examine these mechanisms, we employed a visual discrimination task. We asked participants to perform a perceptual judgment on two briefly presented circles containing unequal number of dots (more dots on the left or right of the screen), while lying in an MRI scanner. Subjects indicated their degree of confidence after each perceptual judgment...