What if the reward is not as yummy? Study of the effects of Successive Negative Contrast in domestic dogs in two different tasks.

Successive Negative Contrast (SNC) occurs when there is a reduction in the quantity or quality of a reward that is expected according to the presence of contextual cues. This induces an emotional response of frustration that is similar to stress. While this phenomenon has been observed in several mammal species, findings in domestic dogs have been inconsistent, although this issue has strong relevance in dog training. The aim of this study was to assess the effects of Successive Negative Contrast in two responses that had already been studied in this species, but with an increase in the methodological rigor and variations in the experimental conditions to examine the generalizability of the phenomenon. To this end, experimental dogs experienced a pre-shift phase in which they received a high-value reward (liver), followed by a post-shift phase in which they obtained a low-value reward (dry dog food), and then a re-shift phase in which the high-value reward was available again. Control dogs received dry food in all phases. The results show a contrast effect on the behavior of following human pointing to obtain food (Study 1). On the contrary, there were no differences in problem solving behavior after the de- and re-evaluation of the reward during a non-social task (Study 2). The results support that Successive Negative Contrast is not a consistent phenomenon in pet dogs. It is possible that certain characteristics of dogs such as the great availability of high-value rewards in their daily lives could attenuate the effects of a reduction in incentive value.