²⁷The RPE formalism could also be interpreted as providing another baseline mechanism, by looking at the change of state-values. Going to a state which has a lower value than the current state, without obtaining any reward, does produce suffering according to the definition of RPE above, as explained in footnotes 19 and 20 in this chapter. In this sense, RPE uses the current state-value as the baseline defining what is “low”. See also footnote 14 on different possibilities of defining the baseline as “expectation”.