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.

Trained dogs do not give up: Effects of advanced training on the persistence of domestic dogs.

Prior research with highly trained dogs suggests they may be more successful than pets in independently solving problems when it is possible, yet they may engage in social strategies involving human partners when they face unsolvable tasks. One of the factors underlying these differences may be their persistence, which is usually studied as motivation towards a task. However, highly trained dogs often need to perform lengthy sequences of behaviors with no reinforcement, highlighting the need for research focusing on their performance under extinction conditions. In this sense, persistence can be also examined as resistance to extinction. We compared 26 trained and untrained adult dogs of various breeds and mixes on a gazing task and a non-social problem solving task, each following a pattern of acquisition and then extinction. Results indicate that trained dogs exhibited a greater resistance to extinction than untrained dogs in both tasks. This increase in persistence could be beneficial for their performance, particularly when they need to conduct lengthy chains of behaviors with no immediate reinforcement.

Showing behavior in Animal Assisted Intervention and pet dogs.

A dog's behavior can indicate the location of hidden food to a human who is unaware of its position. These behavioral patterns are known as showing behavior, which comprise gazing towards the target location and gaze alternation between the human and the target (i.e., hidden food). Although this ability has been extensively studied in pet dogs, research has not yet focused on dogs with other kinds of life experiences, such as dogs working in Animal Assisted Interventions (AAI). These dogs are exposed to novel environments under the guidance of their handlers and previous studies have highlighted the importance of gazing behavior in this population. Therefore, we evaluated AAI and pet dogs on a showing task. Results indicate that dogs overall engaged in showing behavior as they gazed more towards the baited pot and alternated their gaze more on showing trials than control ones. Contrary to our expectations, differences between AAI and pet dogs were minimal. However, owners of AAI dogs were more successful than owners of pet dogs in finding the hidden food in showing trials. This suggests they may be more skillful in reading their dogs' behavior, which can be crucial to ensure their welfare during AAI sessions.

Oxytocin effects on gazing at the human face in retriever dogs.

Oxytocin is a neurohormone involved in domestic dogs' socio-cognitive abilities which appears to be key in the display of gazing behavior as a communicative signal. However, differential effects of oxytocin have been reported in various tasks according to the dogs' breed. In the present study, we evaluated the effect of the intranasal administration of oxytocin on gazing towards the human face in Golden and Labrador Retrievers. This was assessed during a learning task in which dogs had to gaze at the human face in order to receive food that was visible but inaccessible. Results indicate that only intact dogs who received oxytocin exhibited an increase in gazing behavior, while no differences were observed for neutered dogs. This effect could be related to an interaction between oxytocin and steroid hormones in intact dogs. These findings highlight the importance of including modulating factors, such as breed and neutered status, when studying the mechanisms of oxytocin.

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.

Do dogs experience frustration? New contributions on successive negative contrast in domestic dogs (Canis familiaris).

An unexpected change in reward quantity or quality frequently elicits a sharp decrease of responses as well as a negative emotional state. This phenomenon is called successive negative contrast (SNC) and, although it has been observed in numerous mammals, results in dogs have been inconsistent. The aim of this study was to evaluate SNC in dogs, comparing the effects of rewards of different qualities in a non-social task carried out in the dogs' usual environment. Dogs were separated into two experimental groups that experienced a downshift from a high quality reward (liver or sausage) to a low quality one (dry food), as well as a control group that always received dry food. The task involved a dog toy with bone shaped pieces that had to be removed to get the food hidden underneath. When the reward changed from liver to dry food, dogs picked up significantly fewer bones than the control group. However, this effect was not observed with sausage. Results show SNC in dogs in a non-social task carried out in their home environment. Additionally, the importance of the discrepancy in the hedonic value of the rewards is highlighted.

Is previous experience important for inhibitory control? A comparison between shelter and pet dogs in A-not-B and cylinder tasks.

This study compares the performance of two groups of dogs with different levels of social interaction with humans, shelter and pet dogs, in two inhibitory control tasks. (1) In the A-not-B task, dogs were required to resist searching for food in a previously rewarded location, and (2) in the cylinder task, dogs were required to resist approaching visible food directly in favor of a detour reaching response. Our first aim was to evaluate the importance of learning and ontogeny in performing inhibitory tasks. Also, we assessed whether there is a correlation between the two tasks by comparing performance in the same subjects. Results showed significant differences between shelter and pet dogs in the A-not-B task, with poorer performance in shelter dogs. However, no differences were found in the cylinder task. The poorer performance of shelter dogs might be related to their infrequent interaction with humans, which reduces the chances to learn to inhibit certain behaviors. This result would highlight the importance of ontogeny in developing that ability. On the other hand, no correlations were found between the two tasks, which contributes information to the debate about the context specificity of inhibitory control in dogs.

Tolerance to delayed reward tasks in social and non-social contexts.

Domestic dogs have demonstrated striking social skills towards humans, however, there are few studies investigating impulsivity with delay-choice tasks in communicative contexts. In Study 1 we introduced a novel social delay-choice task in which subjects had to choose between one human cueing an immediate, low quality reward and another human signaling a delayed, high quality reward. In Study 2 we evaluated the tolerance to increasing delays using social and non-social cues. We also explored if more self-controlled dogs show any distinct behaviours during delays. Finally, we correlated all results with the Dog Impulsivity Assessment Scale (Wright et al., 2011). In Study 1 dogs reached an average maximum delay of 11.55s. In Study 2 that average was 52.14s with social cues and 40.2s with non-social, but differences were not significant. Tolerance to delays showed high interindividual variation. Dogs remained mostly standing and near the delayed experimenter in the social tasks although we could not to find any distinct coping strategies. No significant correlations were found between the delay reached and behaviours, neither with the scale. These results show the relevance of the parameters and methods used to investigate tolerance to delay of reinforcements. More investigations are required, especially an assessment of the same subjects performing the same tasks using different contexts.