Evidence from behavioral economics suggests that there are at least five specific psychological factors underlying the sunk cost effect:
Taken together, these results suggest that the sunk cost effect may reflect non-standard measures of utility, which is ultimately subjective and unique to the individual.
The framing effect which underlies the sunk cost effect builds upon the concept of extensionality where the outcome is the same regardless of how the information is framed. This is in contradiction to the concept of intentionality which is concerned with whether the presentation of information changes the situation in question.
While these functions are framed differently, regardless of the input 'x', the outcome is analytically equivalent. Therefore, if a rational decision maker were to choose between these two functions, the likelihood of each function being chosen should be the same. However, a framing effect places unequal biases towards preferences that are otherwise equal.