One might take the view that credence is modelling some kind of mental or psychological quantity in the head. Strength of belief is a real psychological quantity and it is this that credence should measure. Unlike the above views, this interpretation of credence isn’t easy to operationalise. It also seems like this understanding of strength of belief distances credence from its role in understanding decision making. The above behaviourist views take belief’s role in decision making to be central to or even definitional of what belief is. This psychological interpretation seems to divorce belief from decision. Whether there are such stable neurological structures is also a matter of some controversy (Fumagalli 2013; Smithson and Pushkarskaya 2015).