Chimpanzees and bonobos use social leverage in an ultimatum game.

The ultimatum game (UG) is widely used to investigate our sense of fairness, a key characteristic that differentiates us from our closest living relatives, bonobos and chimpanzees. Previous studies found that, in general, great apes behave as rational maximizers in the UG. Proposers tend to choose self-maximizing offers, while responders accept most non-zero offers. These studies do not rule out the possibility that apes can behave prosocially to improve the returns for themselves and others. However, this has never been well studied. In this study, we offer chimpanzee and bonobo proposers the possibility of taking into account the leverage of responders over the offers they receive. This leverage takes the form of access to alternatives for responders. We find that proposers tend to propose fairer offers when responders have the option to access alternatives. Furthermore, we find that both species use their leverage to reject unequal offers. Our results suggest that great apes mostly act as rational maximizers in an UG, yet access to alternatives can lead them to change their strategies such as not choosing the self-maximizing offer as proposers and not accepting every offer higher than zero as responders.

Modular E-Collar for Animal Telemetry: An Animal-Centered Design Proposal.

Animal telemetry is a subject of great potential and scientific interest, but it shows design-dependent problems related to price, flexibility and customization, autonomy, integration of elements, and structural design. The objective of this paper is to provide solutions, from the application of design, to cover the niches that we discovered by reviewing the scientific literature and studying the market. The design process followed to achieve the objective involved a development based on methodologies and basic design approaches focused on the human experience and also that of the animal. We present a modular collar that distributes electronic components in several compartments, connected, and powered by batteries that are wirelessly recharged. Its manufacture is based on 3D printing, something that facilitates immediacy in adaptation and economic affordability. The modularity presented by the proposal allows for adapting the size of the modules to the components they house as well as selecting which specific modules are needed in a project. The homogeneous weight distribution is transferred to the comfort of the animal and allows for a better integration of the elements of the collar. This device substantially improves the current offer of telemetry devices for farming animals, thanks to an animal-centered design process.

Gibbons exploit information about what a competitor can see.

How much nonhuman animals understand about seeing has been the focus of comparative cognition research for decades. Many social primates (and other species) are sensitive to cues about what others can and cannot see. Whether this sensitivity evolved in primates through shared descent or convergent evolution remains unclear. The current study tested gibbons-the apes that are least studied yet most distantly related to humans and one of the less social primates-in two food-competition tasks. Specifically, we presented eastern hoolock gibbons, Hoolock leuconedys, and silvery gibbons, Hylobates moloch, with a choice between a contested piece of food visible to both themselves and a human competitor and an uncontested piece visible only to themselves. Subjects successfully stole the uncontested food when the competitor turned away his body (N = 10, experiment 1) and his head (N = 9, experiment 2). However, when the head of the experimenter was oriented towards the contested piece of food, whether the competitor opened or closed his eyes made no difference. Subjects' sensitivity to body- and head-orientation cues was comparable to that of chimpanzees, rhesus macaques, and ring-tailed lemurs-species living in much larger groups than gibbons. These findings support the continuity hypothesis that sensitivity to body- and head-orientation cues is a product of shared descent among primates.

Children, but not great apes, respect ownership.

Access to and control of resources is a major source of costly conflicts. Animals, under some conditions, respect what others control and use (i.e. possession). Humans not only respect possession of resources, they also respect ownership. Ownership can be viewed as a cooperative arrangement, where individuals inhibit their tendency to take others' property on the condition that those others will do the same. We investigated to what degree great apes follow this principle, as compared to human children. We conducted two experiments, in which dyads of individuals could access the same food resources. The main test of respect for ownership was whether individuals would refrain from taking their partner's resources even when the partner could not immediately access and control them. Captive apes (N = 14 dyads) failed to respect their partner's claim on food resources and frequently monopolized the resources when given the opportunity. Human children (N = 14 dyads), tested with a similar apparatus and procedure, respected their partner's claim and made spontaneous verbal references to ownership. Such respect for the property of others highlights the uniquely cooperative nature of human ownership arrangements.

Young children are more willing to accept group decisions in which they have had a voice.

People accept an unequal distribution of resources if they judge that the decision-making process was fair. In this study, 3- and 5-year-old children played an allocation game with two puppets. The puppets decided against a fair distribution in all conditions, but they allowed children to have various degrees of participation in the decision-making process. Children of both ages protested less when they were first asked to agree with the puppets' decision compared with when there was no agreement. When ignored, the younger children protested less than the older children-perhaps because they did not expect to have a say in the process-whereas they protested more when they were given an opportunity to voice their opinion-perhaps because their stated opinion was ignored. These results suggest that during the preschool years, children begin to expect to be asked for their opinion in a decision, and they accept disadvantageous decisions if they feel that they have had a voice in the decision-making process.

Social play as joint action: A framework to study the evolution of shared intentionality as an interactional achievement.

Social play has a complex, cooperative nature that requires substantial coordination. This has led researchers to use social games to study cognitive abilities like shared intentionality, the skill and motivation to share goals and intentions with others during joint action. We expand this proposal by considering play as a joint action and examining how shared intentionality is achieved during human joint action. We describe how humans get into, conduct, and get out of joint actions together in an orderly way, thereby constructing the state of "togetherness" characteristic of shared intentionality. These processes play out as three main phases, the opening (where participants are ratified and joint commitments are established), the main body (where progress, ongoing commitments, and possible role reversals are coordinated), and the closing (where the intention to terminate the action is coordinated and where participants take leave of each other). We use this process in humans as a framework for examining how various animal species get into, maintain, and get out of play bouts. This comparative approach constitutes an alternative measure of those species' possession of shared intentionality. Using this framework, we review the play literature on human children and different social species of mammals and birds in search of behavioral markers of shared intentionality in the coordination of play bouts. We discuss how our approach could shed light on the evolution of the special human motivation to cooperate and share psychological states with others.

Late Emergence of the First Possession Heuristic: Evidence From a Small-Scale Culture.

Western preschool children often assign ownership based on first possession and some theorists have proposed that this judgment might be an early emerging, innate bias. Five- to 9-year-olds (n = 112) from a small-scale group in Kenya (Kikuyu) watched videotaped interactions of two women passing an object. The object's starting position and the women's gestures were varied. Use of the first possession heuristic increased with age, and 8- to 9-year-olds performed similarly to German 5-year-olds (n = 24). Starting position and gestures had no effect. A control study confirmed that 5-year-old Kikuyus (n = 20) understood the video material. The findings reveal that the first possession heuristic follows different developmental trajectories cross-culturally and stress the role of children's sociocultural environment.

Procedural justice in children: Preschoolers accept unequal resource distributions if the procedure provides equal opportunities.

When it is not possible to distribute resources equitably to everyone, people look for an equitable or just procedure. In the current study, we investigated young children's sense of procedural justice. We tested 32 triads of 5-year-olds in a new resource allocation game. Triads were confronted with three unequal reward packages and then agreed on a procedure to allocate them among themselves. To allocate the rewards, they needed to use a "wheel of fortune." Half of the groups played with a fair wheel (where each child had an equal chance of obtaining each reward package), and the other half played with an unfair wheel. We analyzed children's interactions when using the wheel and conducted an interview with each child after the game was over. Children using the unfair wheel often decided to change the rules of the game, and they also rated it as an unfair procedure in the interview. In contrast, children who played with the fair wheel were mostly accepting of both the outcome and the procedure. Overall, we found that children as young as preschool age are already sensitive not only to distributive justice but to procedural justice as well.

Domestic dogs and puppies can use human voice direction referentially.

Domestic dogs are particularly skilled at using human visual signals to locate hidden food. This is, to our knowledge, the first series of studies that investigates the ability of dogs to use only auditory communicative acts to locate hidden food. In a first study, from behind a barrier, a human expressed excitement towards a baited box on either the right or left side, while sitting closer to the unbaited box. Dogs were successful in following the human's voice direction and locating the food. In the two following control studies, we excluded the possibility that dogs could locate the box containing food just by relying on smell, and we showed that they would interpret a human's voice direction in a referential manner only when they could locate a possible referent (i.e. one of the boxes) in the environment. Finally, in a fourth study, we tested 8-14-week-old puppies in the main experimental test and found that those with a reasonable amount of human experience performed overall even better than the adult dogs. These results suggest that domestic dogs' skills in comprehending human communication are not based on visual cues alone, but are instead multi-modal and highly flexible. Moreover, the similarity between young and adult dogs' performances has important implications for the domestication hypothesis.

The ontogenetic ritualization of bonobo gestures.

Great apes communicate with gestures in flexible ways. Based on several lines of evidence, Tomasello and colleagues have posited that many of these gestures are learned via ontogenetic ritualization-a process of mutual anticipation in which particular social behaviors come to function as intentional communicative signals. Recently, Byrne and colleagues have argued that all great ape gestures are basically innate. In the current study, for the first time, we attempted to observe the process of ontogenetic ritualization as it unfolds over time. We focused on one communicative function between bonobo mothers and infants: initiation of "carries" for joint travel. We observed 1,173 carries in ten mother-infant dyads. These were initiated by nine different gesture types, with mothers and infants using many different gestures in ways that reflected their different roles in the carry interaction. There was also a fair amount of variability among the different dyads, including one idiosyncratic gesture used by one infant. This gestural variation could not be attributed to sampling effects alone. These findings suggest that ontogenetic ritualization plays an important role in the origin of at least some great ape gestures.

Comparative curiosity: How do great apes and children deal with uncertainty?

Humans are perhaps the most curious animals on earth, but to what extent our innate motivations for discovering new information are shared with our closest relatives remain poorly understood. To shed light on this question, we presented great apes with two experimental paradigms in which they had to initially choose between an empty opaque cup and a baited opaque cup with rewards invisible to the ape in study 1, or to choose between a transparent cup with rewards or a baited opaque cup with rewards invisible to the ape in studies 2 and 3. We also presented young children with scenarios comparable to the second paradigm (studies 4 and 5). Notably, after the initial choice phase, we presented participants with potential alternatives providing better rewards than the previously secured options. Importantly, those alternatives shared some features with the uncertain options, giving subjects the possibility to relate both options through analogical reasoning. We found that most great apes were not curious about the uncertain options. They only explored those options after they were presented with the alternatives. Children, instead, explored the uncertain options before the alternatives were presented, showing a higher degree of curiosity than the great apes. We argue that differences between children and apes mostly lay in motivational dispositions to explore the unknown.

Use of Augmentative Interspecies Communication devices in animal language studies: A review.

Countless discussions have been generated by the animal language studies, specifically those utilizing mechanical interfaces, termed here Augmentative Interspecies Communication (AIC) devices (e.g., lexigrams; magnetic chips; keyboards). Overall, three concerns dominate the field: (1) claims that AIC device using animals manifest linguistic skills remain nebulous, and simpler alternative mechanisms have been proposed (e.g., associative learning); (2) such methodology may be unsuitable as some theorize AIC device interfaces are not sufficiently ecologically relevant to foster meaningful use; (3) data may be considered dubious due to potential cueing from experimenters and lack of systematicity in reporting training and performance. Despite such controversy-which eventually led to the field's deterioration around the last quarter of the twentieth century-this research also saw important successes, such as improvements in captive animal welfare, the outcomes of which hold promise for future interspecies communication work. This article is categorized under: Linguistics > Evolution of Language.

Beyond Single-Mindedness: A Figure-Ground Reversal for the Cognitive Sciences.

A fundamental fact about human minds is that they are never truly alone: all minds are steeped in situated interaction. That social interaction matters is recognized by any experimentalist who seeks to exclude its influence by studying individuals in isolation. On this view, interaction complicates cognition. Here, we explore the more radical stance that interaction co-constitutes cognition: that we benefit from looking beyond single minds toward cognition as a process involving interacting minds. All around the cognitive sciences, there are approaches that put interaction center stage. Their diverse and pluralistic origins may obscure the fact that collectively, they harbor insights and methods that can respecify foundational assumptions and fuel novel interdisciplinary work. What might the cognitive sciences gain from stronger interactional foundations? This represents, we believe, one of the key questions for the future. Writing as a transdisciplinary collective assembled from across the classic cognitive science hexagon and beyond, we highlight the opportunity for a figure-ground reversal that puts interaction at the heart of cognition. The interactive stance is a way of seeing that deserves to be a key part of the conceptual toolkit of cognitive scientists.

One-year-old infants follow others' voice direction.

We investigated 1-year-old infants' ability to infer an adult's focus of attention solely on the basis of her voice direction. In Studies 1 and 2, 12- and 16-month-olds watched an adult go behind a barrier and then heard her verbally express excitement about a toy hidden in one of two boxes at either end of the barrier. Even though they could not see the adult, infants of both ages followed her voice direction to the box containing the toy. Study 2 showed that infants could do this even when the adult was positioned closer to the incorrect box while she vocalized toward the correct one (and thus ruled out the possibility that infants were merely approaching the source of the sound). In Study 3, using the same methods as in Study 2, we found that chimpanzees performed the task at chance level. Our results show that infants can determine the focus of another person's attention through auditory information alone-a useful skill for establishing joint attention.

Universals and cultural variation in turn-taking in conversation.

Informal verbal interaction is the core matrix for human social life. A mechanism for coordinating this basic mode of interaction is a system of turn-taking that regulates who is to speak and when. Yet relatively little is known about how this system varies across cultures. The anthropological literature reports significant cultural differences in the timing of turn-taking in ordinary conversation. We test these claims and show that in fact there are striking universals in the underlying pattern of response latency in conversation. Using a worldwide sample of 10 languages drawn from traditional indigenous communities to major world languages, we show that all of the languages tested provide clear evidence for a general avoidance of overlapping talk and a minimization of silence between conversational turns. In addition, all of the languages show the same factors explaining within-language variation in speed of response. We do, however, find differences across the languages in the average gap between turns, within a range of 250 ms from the cross-language mean. We believe that a natural sensitivity to these tempo differences leads to a subjective perception of dramatic or even fundamental differences as offered in ethnographic reports of conversational style. Our empirical evidence suggests robust human universals in this domain, where local variations are quantitative only, pointing to a single shared infrastructure for language use with likely ethological foundations.

Every product needs a process: unpacking joint commitment as a process across species.

Joint commitment, the feeling of mutual obligation binding participants in a joint action, is typically conceptualized as arising by the expression and acceptance of a promise. This account limits the possibilities of investigating fledgling forms of joint commitment in actors linguistically less well-endowed than adult humans. The feeling of mutual obligation is one aspect of joint commitment (the product), which emerges from a process of signal exchange. It is gradual rather than binary; feelings of mutual obligation can vary in strength according to how explicit commitments are perceived to be. Joint commitment processes are more complex than simple promising, in at least three ways. They are affected by prior joint actions, which create precedents and conventions that can be embodied in material arrangements of institutions. Joint commitment processes also arise as solutions to generic coordination problems related to opening up, maintaining and closing down joint actions. Finally, during joint actions, additional, specific commitments are made piecemeal. These stack up over time and persist, making it difficult for participants to disengage from joint actions. These complexifications open up new perspectives for assessing joint commitment across species. This article is part of the theme issue 'Revisiting the human 'interaction engine': comparative approaches to social action coordination'.

Sharing Rewards Undermines Coordinated Hunting.

Coordinated hunting is widely observed in animals, and sharing rewards is often considered a major incentive for its success. While current theories about the role played by sharing in coordinated hunting are based on correlational evidence, we reveal the causal roles of sharing rewards through computational modeling with a state-of-the-art Multi-agent Reinforcement Learning (MARL) algorithm. We show that counterintuitively, while selfish agents reach robust coordination, sharing rewards undermines coordination. Hunting coordination modeled through sharing rewards (1) suffers from the free-rider problem, (2) plateaus at a small group size, and (3) is not a Nash equilibrium. Moreover, individually rewarded predators outperform predators that share rewards, especially when the hunting is difficult, the group size is large, and the action cost is high. Our results shed new light on the actual importance of prosocial motives for successful coordination in nonhuman animals and suggest that sharing rewards might simply be a byproduct of hunting, instead of a design strategy aimed at facilitating group coordination. This also highlights that current artificial intelligence modeling of human-like coordination in a group setting that assumes rewards sharing as a motivator (e.g., MARL) might not be adequately capturing what is truly necessary for successful coordination.

How 2- and 4-year-old children coordinate social interactions with peers.

The Interaction Engine Hypothesis postulates that humans have a unique ability and motivation for social interaction. A crucial juncture in the ontogeny of the interaction engine could be around 2-4 years of age, but observational studies of children in natural contexts are limited. These data appear critical also for comparison with non-human primates. Here, we report on focal observations on 31 children aged 2- and 4-years old in four preschools (10 h per child). Children interact with a wide range of partners, many infrequently, but with one or two close friends. Four-year olds engage in cooperative social interactions more often than 2-year olds and fight less than 2-year olds. Conversations and playing with objects are the most frequent social interaction types in both age groups. Children engage in social interactions with peers frequently (on average 13 distinct social interactions per hour) and briefly (28 s on average) and shorter than those of great apes in comparable studies. Their social interactions feature entry and exit phases about two-thirds of the time, less frequently than great apes. The results support the Interaction Engine Hypothesis, as young children manifest a remarkable motivation and ability for fast-paced interactions with multiple partners. This article is part of the theme issue 'Revisiting the human 'interaction engine': comparative approaches to social action coordination'.

In situ bidirectional human-robot value alignment.

A prerequisite for social coordination is bidirectional communication between teammates, each playing two roles simultaneously: as receptive listeners and expressive speakers. For robots working with humans in complex situations with multiple goals that differ in importance, failure to fulfill the expectation of either role could undermine group performance due to misalignment of values between humans and robots. Specifically, a robot needs to serve as an effective listener to infer human users' intents from instructions and feedback and as an expressive speaker to explain its decision processes to users. Here, we investigate how to foster effective bidirectional human-robot communications in the context of value alignment-collaborative robots and users form an aligned understanding of the importance of possible task goals. We propose an explainable artificial intelligence (XAI) system in which a group of robots predicts users' values by taking in situ feedback into consideration while communicating their decision processes to users through explanations. To learn from human feedback, our XAI system integrates a cooperative communication model for inferring human values associated with multiple desirable goals. To be interpretable to humans, the system simulates human mental dynamics and predicts optimal explanations using graphical models. We conducted psychological experiments to examine the core components of the proposed computational framework. Our results show that real-time human-robot mutual understanding in complex cooperative tasks is achievable with a learning model based on bidirectional communication. We believe that this interaction framework can shed light on bidirectional value alignment in communicative XAI systems and, more broadly, in future human-machine teaming systems.

Gibbon strategies in a food competition task.

Social primates face conflicts of interest with other partners when their individual and collective interests collide. Despite living in small, primarily bonded, groups compared to other social primates, gibbons are not exempt from these conflicts in their everyday lives. In the current task, we asked whether dyads of gibbons would solve a conflict of interest over food rewards. We presented dyads of gibbons with a situation in which they could decide whether to take an active role and pull a handle to release food rewards at a distance or take a passive role and avoid action. In this situation, the passive partner could take an advantageous position to obtain the rewards over the active partner. Gibbons participated in three conditions: a control condition with no food rewards, a test condition with indirect food rewards and a test condition with direct food rewards. In both test conditions, five rewards were released at a distance from the handle. In addition, the active individual could obtain one extra food reward from the handle in the direct food condition. We found that gibbons acted more often in the two conditions involving food rewards, and waited longer in the indirect compared to the direct food condition, thus suggesting that they understood the task contingencies. Surprisingly, we found that in a majority of dyads, individuals in the active role obtained most of the payoff compared to individuals in the passive role in both food conditions. Furthermore, in some occasions individuals in the active role did not approach the location where the food was released. These results suggest that while gibbons may strategize to maximize benefits in a competitive food task, they often allowed their partners to obtain better rewards. Our results highlight the importance of social tolerance and motivation as drivers promoting cooperation in these species.