Mounting evidence has suggested that structures such as the anterior cingulate cortex (ACC) and other areas within the medial-frontal cortex are part of a reinforcement learning system responsible for the optimization of behaviour (Holroyd & Coles, 2002). However, we also learn without reinforcement and it has been less clear what neural structures are recruited in these instances. The P300 component of the human event-related brain potential (ERP) has been intensely researched in regards to context updating and the processing of novel stimuli (Spencer, Dien, & Donchin, 2001). Here, I sought to elaborate on the role of the P300 ERP component in implicit learning of stimulus frequencies – learning driven by the stimulus itself and not reward feedback. I propose over the course of three experiments that I have provided evidence indicating that the P300 and its neural sources play a role in feedback-free learning mechanisms. Specifically, in a feedback-free paradigm participants are shown to learn stimulus frequencies. While this occurs, P300 amplitude scales in line with participant behaviour and stimulus frequency. A common trend is revealed in how quickly this amplitude scaling occurs, suggesting further mechanisms are at play. Trial-by-trial analysis ultimately shows that behavioural prediction error formula and neural correlate prediction errors utilize a nearly identical function. These trends hold even in a passive auditory task in which the participant is fully distracted. / Graduate