Basic psychophysics tells us that decisions are rarely perfect: even with identical stimuli choice accuracy fluctuates and errors are often made. Metacognition allows appraisal of this uncertainty and correction of errors. For more complex value-based decisions (also known as economic decisions), however, metacognitive processes are poorly understood. In particular, how subjective confidence and valuation of choice options interact at the level of brain and behaviour is unknown. In this talk I will present recent work we conducted in my lab to investigate this relationship (combining psychophysics paradigms, computational modeling and imaging tools). The aim of this approach is to provide new links between uncertainty in value computation and reports of confidence. Finally I will show how humans can use their metacognitive awareness to correct and improve future decisions.