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.

Still-face effect in domestic dogs: comparing untrained with trained and animal assisted interventions dogs.

The still-face effect has been extensively studied in human infants and comprises the reduction in affiliative behaviors and increased stress that occurs after a sudden interruption of social interaction with a caregiver. Domestic dogs (Canis familiaris) are model candidates for showing this effect, as they form deep bonds with their owners and interspecific social interaction is reinforcing to them. The aim of these studies was to assess if companion dogs exhibit the still-face effect and whether prior experiences during ontogeny modulate this effect. To this end, Study 1 compared dogs with different levels of training (untrained, intermediate, and advanced), while Study 2 assessed dogs that participated in Animal Assisted Interventions (AAIs) and companion dogs (CDs). The procedure was carried out virtually and comprised three phases lasting 1 min: interaction, still-face (the owner turned suddenly indifferent), and reunion (the interaction was resumed). Dogs exhibited a decrease in proximity to and contact with the owner, as well as an increase in begging and stress behaviors during the still-face phase. Moreover, this was not observed in a control condition in which the interaction continued in the same way during all three phases, discarding alternative explanations for these changes. These results show that dogs experience a still-face effect in a similar way to infants, highlighting the value interspecific social interaction has for dogs. Nevertheless, the absence of differences according to their training level or participation in AAIs suggests this is a robust phenomenon, which appears to be less susceptible to the influences of ontogenetic experiences.

Gazing as a help requesting behavior: a comparison of dogs participating in animal-assisted interventions and pet dogs.

Dogs tend to gaze at humans when they are confronted with inaccessible food during an unsolvable task, which is often interpreted as a help requesting behavior. Dogs who participate in animal-assisted interventions (AAI) interact with many people during their lives and prior studies have emphasized the importance of gazing in their communication. We compared the behavior of AAI (n = 15) and pet (n = 16) dogs during an unsolvable task, using a container fixed to a wooden board with inaccessible food inside, while the owner and an unfamiliar woman stood facing each other at the sides of the board ignoring the dog. Results showed that AAI dogs spent significantly more time gazing and alternated their gaze more frequently between the container and the people than pet dogs. In addition, they spent more time in contact with the unfamiliar person. However, no significant differences were found in the time dogs of either group gazed towards the owner compared to the unfamiliar person, in the frequency of gaze alternation or in the time spent interacting with the apparatus. In line with prior studies, these results suggest that gazing may be a significant communicative response in AAI dogs, which could probably contribute to having a better coordination with their handler. A greater understanding of the characteristics of this population may aid the selection and training of AAI dogs, which is particularly relevant given the increased popularity of AAI nowadays.