Juliane Kaminski

Recent research has tried to determine whether and under which conditions domestic dogs ( Canis familiaris ) engage in prosocial and potentially altruistic behaviour. A common paradigm used to test this is the so-called prosocial choice test. This is a task in which the animal can choose to operate an apparatus based on the outcome. For example, this could involve delivering food to themselves, to another individual, to both, or to neither. The aim of the current study was to investigate dogs’ collaborative tendencies with humans, with the use of a novel prosocial choice test paradigm. This paradigm was designed to take into account the fact that predators may have a more natural tendency to pull vertically rather than horizontally. Our paradigm is based on pulleys that are operated by the dogs, an action which dogs mastered without extensive training. All dogs ( N = 16) participated in three experimental conditions (selfish-, prosocial- and altruistic condition) and two control conditions (no-reward- and partner-absent control). We further tested to what extent the between subjects’ familiarity with the human partner (owner vs. stranger) mattered to the dogs. The dogs were more likely to operate the apparatus when they received a reward (selfish- and prosocial condition) than when they did not (altruistic- and no-reward condition). In addition, the absence of a partner, owner or stranger only marginally affected the dogs’ tendency to pull. Based on our findings, we cannot conclude that dogs make altruistic or prosocial choices; rather, they appear motivated by selfish interests. We discuss the possibility that even small procedural changes can have large implications on the behaviour of the dogs during the tests.

Domestic dogs demonstrate sensitivity to human gaze and attentiveness, but evidence is mixed for their understanding of human knowledge, in the sense of understanding what a person has or has not seen. Here we tested whether pet dogs take a human competitor’s past visual access into account in a 3-choice food competition task. The dogs ( N = 22) observed food being hidden under 2 of 3 cups, and witnessed how their human competitor saw only one baiting. When the human chose first, dogs were expected to avoid the cup she had seen baited; when dogs chose first, they were expected to choose randomly between baited cups, or favour the cup both had seen baited. However, the dogs chose randomly between the baited cups, regardless of who had first choice. The dogs did choose the cup only they had seen baited above chance only when the competitor chose first, suggesting a potential preference for this cup only in this situation, but they did not choose this cup more than the cup both had seen. Therefore, the current study provides no clear evidence that pet dogs infer others’ knowledge from past visual access. The combination of cognitive steps required to be successful in this task might have been too demanding for the dogs. Alternatively, the competitive setting used may not be as suitable for domestic dogs as it is for other species. Further research in ecologically relevant settings may clarify the extent and limits of dogs’ understanding of others’ knowledge.

Only a few dogs in the world are label-learners, with the ability to process and retain a vast number of object referents. Here we present data from a battery of cognitive tests that could explain why they outperform their conspecifics. In a citizen science approach, we instructed dog owners across five different countries, on how to administer a series of eight cognitive tests to their dogs. The group of label-learner dogs (N = 11) was then compared to control dogs (N = 11) that did not have that label learning ability. Our experiment demonstrates, for the first time, that the label-learner dogs’ ability might be based on measurable individual differences in three specific cognitive domains: their interest in novel objects, their targeted interest in objects and their inhibitory skills. Future research, replicating the results on a larger sample, can explore if the label-learner dogs’ outstanding cognitive skills are already present at the puppy stage or develop over time.

We investigated children’s and non-human great apes’ ability to anticipate others’ choices from their evident food preferences—regardless of whether these preferences deviate or align with one’s own. We assessed children from three culturally-diverse societies (Namibia, Germany, and Samoa; N = 71; age range = 5–11) and four non-human great ape species (chimpanzees (Pan troglodytes), bonobos (Pan paniscus), gorillas (Gorilla gorilla), and orangutans (Pongo abelii); N = 25; age range = 7–29) regarding their choices in a dyadic food-retrieval task. Across conditions, participants’ preferences were either aligned (same preference condition) or opposed (opposite preference condition) to those of their competitors. Children across societies altered their choices based on their competitor’s preferences, indicating a cross-culturally recurrent capacity to anticipate others’ choices relying on preferences-based inferences. In contrast to human children, all non-human great apes chose according to their own preferences but independent of those of their competitors. In sum, these results suggest that the tendency to anticipate others’ choices based on their food preferences is cross-culturally robust and, among the great apes, most likely specific to humans.

To promote collaboration across canine science, address replicability issues, and advance open science practices within animal cognition, we have launched the ManyDogs consortium, modeled on similar ManyX projects in other fields. We aimed to create a collaborative network that (a) uses large, diverse samples to investigate and replicate findings, (b) promotes open science practices of pre-registering hypotheses, methods, and analysis plans, (c) investigates the influence of differences across populations and breeds, and (d) examines how different research methods and testing environments influence the robustness of results. Our first study combines a phenomenon that appears to be highly reliable—dogs’ ability to follow human pointing—with a question that remains controversial: do dogs interpret pointing as a social communicative gesture or as a simple associative cue? We collected data (N = 455) from 20 research sites on two conditions of a 2-alternative object choice task: (1) Ostensive (pointing to a baited cup after making eye-contact and saying the dog’s name); (2) Non-ostensive (pointing without eye-contact, after a throat-clearing auditory control cue). Comparing performance between conditions, while both were significantly above chance, there was no significant difference in dogs’ responses. This result was consistent across sites. Further, we found that dogs followed contralateral, momentary pointing at lower rates than has been reported in prior research, suggesting that there are limits to the robustness of point-following behavior: not all pointing styles are equally likely to elicit a response. Together, these findings underscore the important role of procedural details in study design and the broader need for replication studies in canine science.

Significance: Dogs were shaped during the course of domestication both in their behavior and in their anatomical features. Here we show that domestication transformed the facial muscle anatomy of dogs specifically for facial communication with humans. A muscle responsible for raising the inner eyebrow intensely is uniformly present in dogs but not in wolves. Behavioral data show that dogs also produce the eyebrow movement significantly more often and with higher intensity than wolves do, with highest-intensity movements produced exclusively by dogs. Interestingly, this movement increases paedomorphism and resembles an expression humans produce when sad, so its production in dogs may trigger a nurturing response. We hypothesize that dogs’ expressive eyebrows are the result of selection based on humans’ preferences.

Most mammalian species produce facial expressions. Historically, animal facial expressions have been considered inflexible and involuntary displays of emotional states rather than active attempts to communicate with others. In the current study, we aimed to test whether domestic dog facial expressions are subject to audience effects and/ or changes in response to an arousing stimulus (e.g. food) alone. We presented dogs with an experimental situation in which a human demonstrator was either attending to them or turned away, and varied whether she presented food or not. Dogs produced significantly more facial movements when the human was attentive than when she was not. The food, however, as a non-social but arousing stimulus, did not affect the dogs’ behaviour. The current study is therefore evidence that dogs are sensitive to the human’s attentional state when producing facial expressions, suggesting that facial expressions are not just inflexible and involuntary displays of emotional states, but rather potentially active attempts to communicate with others.