Toyomaki & Murohashi [28] reported two important observations on ORP to imply that ORP was sensitive to both the quality (loss/gain) and quantity (larger/smaller) of the bet: 1) The ORP peak amplitudes of win conditions were larger than those of lose and neutral conditions, and 2) ORP peak amplitude of the 500 Yen condition was larger than those of 10 and 100 Yen conditions. Despite these prominent studies, the functional nature of ORP (in terms of quality and quantity of outcomes) is still unclear, maybe due to the paucity of studies, as the gambling paradigm is relatively new. On the other hand, a similar component in an error paradigm, called the error positivity (Pe), has been relatively well studied [29]. Pe is shown to reflect conscious recognition and motivational significance of the error in choice-reaction paradigms [29, 30]. On the other hand, the positivity in gambling paradigms (ORP) is considered to index the subjective evaluation of the magnitude of outcome in gambling tasks [22, 28]. However, the functional significance of ORP has not yet been validated by diverse gambling paradigms.
