The effort justification paradigm - wherein people prefer rewards requiring more effort - is often explained by cognitive dissonance (discomfort experienced when by holding contradictory beliefs and/ or behaviors). Contrast theory provides an alternative by explaining that this preference is due to a greater difference between participant's starting and ending hedonic states. To differentiate these theories, dogs participated in an effort justification paradigm, hearing a severely or mildly annoying noise before receiving one of two differently colored treats. Afterwards, they were given a preference test. Cognitive dissonance and effort justification theories both expect dogs to prefer the treat associated with the severe noise. However, when the treat is not contingent on the noise, contrast theory predicts dogs to prefer the treat associated with the severely annoying noise and cognitive dissonance theory predicts no preference. The results were inconclusive - the effort justification effect was not found in the contingent or non-contingent treatment. Thus, it is still too soon to tell whether dogs or other animals experience cognitive dissonance.
Fischer, Ethan, "Do Dogs Experience Cognitive Dissonance?" (2015). Honors Projects. 171.