Task Design Influences Prosociality in Captive Chimpanzees (Pan troglodytes)

Chimpanzees confer benefits on group members, both in the wild and in captive populations. Experimental studies of how animals allocate resources can provide useful insights about the motivations underlying prosocial behavior, and understanding the relationship between task design and prosocial behavior provides an important foundation for future research exploring these animals'' social preferences. A number of studies have been designed to assess chimpanzees'' preferences for outcomes that benefit others (prosocial preferences), but these studies vary greatly in both the results obtained and the methods used, and in most cases employ procedures that reduce critical features of naturalistic social interactions, such as partner choice. The focus of the current study is on understanding the link between experimental methodology and prosocial behavior in captive chimpanzees, rather than on describing these animals'' social motivations themselves. We introduce a task design that avoids isolating subjects and allows them to freely decide whether to participate in the experiment. We explore key elements of the methods utilized in previous experiments in an effort to evaluate two possibilities that have been offered to explain why different experimental designs produce different results: (a) chimpanzees are less likely to deliver food to others when they obtain food for themselves, and (b) evidence of prosociality may be obscured by more “complex” experimental apparatuses (e.g., those including more components or alternative choices). Our results suggest that the complexity of laboratory tasks may generate observed variation in prosocial behavior in laboratory experiments, and highlights the need for more naturalistic research designs while also providing one example of such a paradigm.     

Short-term compassion training increases prosocial behavior in a newly developed prosocial game

Compassion has been suggested to be a strong motivator for prosocial behavior. While research has demonstrated that compassion training has positive effects on mood and health, we do not know whether it also leads to increases in prosocial behavior. We addressed this question in two experiments. In Experiment 1, we introduce a new prosocial game, the Zurich Prosocial Game (ZPG), which allows for repeated, ecologically valid assessment of prosocial behavior and is sensitive to the influence of reciprocity, helping cost, and distress cues on helping behavior. Experiment 2 shows that helping behavior in the ZPG increased in participants who had received short-term compassion training, but not in participants who had received short-term memory training. Interindividual differences in practice duration were specifically related to changes in the amount of helping under no-reciprocity conditions. Our results provide first evidence for the positive impact of short-term compassion training on prosocial behavior towards strangers in a training-unrelated task.     

It’s Not My Fault: Postdictive Modulation of Intentional Binding by Monetary Gains and Losses

Sense of agency refers to the feeling that one’s voluntary actions caused external events. Past studies have shown that compression of the subjective temporal interval between actions and external events, called intentional binding, is closely linked to the experience of agency. Current theories postulate that the experience of agency is constructed via predictive and postdictive pathways. One remaining problem is the source of human causality bias; people often make misjudgments on the causality of voluntary actions and external events depending on their rewarding or punishing outcomes. Although human causality bias implies that sense of agency can be modified by post-action information, convincing empirical findings for this issue are lacking. Here, we hypothesized that sense of agency would be modified by affective valences of action outcomes. To examine this issue, we investigated how rewarding and punishing outcomes following voluntary action modulate behavioral measures of agency using intentional binding paradigm and classical conditioning procedures. In the acquisition phase, auditory stimuli were paired with positive, neutral or negative monetary outcomes. Tone-reward associations were evaluated using reaction times and preference ratings. In the experimental session, participants performed a variant of intentional binding task, where participants made timing judgments for onsets of actions and sensory outcomes while playing simple slot games. Our results showed that temporal binding was modified by affective valences of action outcomes. Specifically, intentional binding was attenuated when negative outcome occurred, consistent with self-serving bias. Our study not only provides evidence for postdictive modification of agency, but also proposes a possible mechanism of human causality bias.     

Watchful eyes: implicit observability cues and voting

Explicit social pressure has been shown to be a powerful motivator of prosocial behavior like voting in elections. In this study, I replicate and extend the findings of a randomized field experiment designed to study the impact of more subtle, implicit social pressure treatments on voting. The results of the original experiment, conducted in the October 2011 municipal elections in Key West, Florida, demonstrated that even subtle, implicit observability cues, like a pair of stylized eyes facing subjects, effectively mobilized citizens to vote, by about as much as explicit surveillance cues. The replication study, conducted in Lexington, KY, during the November 2011 gubernatorial election, corroborates these findings and suggests that eyes effect on average does not likely depend on the gender of eyespots used. Taken together, the two field experiments provide strong support for the notion studies that humans are evolutionarily programmed to respond to certain stimuli and that exposure to images that implicitly signal observability is sufficient to stimulate prosocial behavior.     

Natural-field dictator game shows no altruistic giving

Economic experiments are increasingly being used in a number of research areas and are a major source of data guiding the debate surrounding the nature of human prosociality. The degree to which experiment behavior accurately reflects external behavior, however, has long been debated. A number of recent studies have revealed just how remarkably sensitive participants are to cues of a lack of anonymity. Similarly, others have suggested that the very structure of the experimental context induces participants to choose prosocial options. In order to truly create anonymous conditions and to eliminate the effects of experimental contexts, participants must not be aware of their participation. Here, I present the results of a natural-field Dictator Game in which participants are presented with a believable endowment and provided an opportunity to divide the endowment with a stranger without knowing that they are taking part in an experiment. No participants gave any portion of the endowment to the stranger. Baseline frequencies of prosocial behaviors exhibited under experimental contexts might therefore be substantially inflated compared to those exhibited under natural contexts.     

Manipulating Shape Cues in Dynamic Human Faces: Sexual Dimorphism is Preferred in Female but not Male Faces

Sexual dimorphism in the human face has been linked to attractiveness, and computer‐graphic techniques have been useful in this field by allowing experimental manipulation of dimorphism. However, a limitation of much research is its reliance on static pictorial stimuli, whereas real faces are dynamic, as is much courtship behaviour throughout nature. Furthermore, little is known about possible interactions between static and dynamic facial cues and attractiveness. We adapted well‐established face‐morphing technology to manipulate sexual dimorphism in male and female dynamic facial displays depicting prosocial and antisocial behaviour. Masculinised and feminised versions of these videos were presented as a two‐alternative forced choice task to measure preferences. Feminised female videos were preferred in both movement contexts, as expected. More surprisingly, no directional preference for masculinity or femininity was evident for the male videos in either context. Further analysis showed that the movement of the faces (prosocial vs. antisocial) had no effect on attractiveness ratings. Results were the same with static stimuli and did not conflict with findings from the wider literature using static faces. These findings suggest that the new technique we describe is a valid way to manipulate facial shape in videos and can now be widely applied to future studies of facial morphing.     

A decision-making model based on a spiking neural circuit and synaptic plasticity

To adapt to the environment and survive, most animals can control their behaviors by making decisions. The process of decision-making and responding according to cues in the environment is stable, sustainable, and learnable. Understanding how behaviors are regulated by neural circuits and the encoding and decoding mechanisms from stimuli to responses are important goals in neuroscience. From results observed in Drosophila experiments, the underlying decision-making process is discussed, and a neural circuit that implements a two-choice decision-making model is proposed to explain and reproduce the observations. Compared with previous two-choice decision making models, our model uses synaptic plasticity to explain changes in decision output given the same environment. Moreover, biological meanings of parameters of our decision-making model are discussed. In this paper, we explain at the micro-level (i.e., neurons and synapses) how observable decision-making behavior at the macro-level is acquired and achieved.     

Eyes,More Than Other Facial Features,Enhance Real-World Donation Behavior

Humans often behave more prosocially when being observed in person and even in response to subtle eye cues, purportedly to manage their reputation. Previous research on this phenomenon has employed the “watching eyes paradigm,” in which adults displayed greater prosocial behavior in the presence of images of eyes versus inanimate objects. However, the robustness of the effect of eyes on prosocial behavior has recently been called into question. Therefore, the first goal of the present study was to attempt to replicate this effect. Additionally, it remains unclear whether the watching-eyes effect is driven specifically by reputation management (owing to the monitoring function of the eyes) or whether any cues indexing human presence more generally also have a similar effect. To address these questions, the current study compared prosocial behavior in the presence of eyes versus inanimate objects as well as other human features. The study was conducted as a field experiment at a children’s museum. Each week, the donation signs were changed to show eyes, noses, mouths, or chairs. Total donation amount and number of patrons per week were recorded. Participants donated more when they were exposed to eyes than to inanimate objects (chairs). We thus replicated the previously reported watching-eyes effect. Moreover, more money was donated when individuals were exposed to eyes than to more general cues of human presence (nose and mouth). The current findings suggest that eyes play a special role in promoting cooperation in humans, likely by serving as cues of monitoring and thus eliciting reputation management behavior.     

Visual Benefits in Apparent Motion Displays: Automatically Driven Spatial and Temporal Anticipation Are Partially Dissociated

Many behaviourally relevant sensory events such as motion stimuli and speech have an intrinsic spatio-temporal structure. This will engage intentional and most likely unintentional (automatic) prediction mechanisms enhancing the perception of upcoming stimuli in the event stream. Here we sought to probe the anticipatory processes that are automatically driven by rhythmic input streams in terms of their spatial and temporal components. To this end, we employed an apparent visual motion paradigm testing the effects of pre-target motion on lateralized visual target discrimination. The motion stimuli either moved towards or away from peripheral target positions (valid vs. invalid spatial motion cueing) at a rhythmic or arrhythmic pace (valid vs. invalid temporal motion cueing). Crucially, we emphasized automatic motion-induced anticipatory processes by rendering the motion stimuli non-predictive of upcoming target position (by design) and task-irrelevant (by instruction), and by creating instead endogenous (orthogonal) expectations using symbolic cueing. Our data revealed that the apparent motion cues automatically engaged both spatial and temporal anticipatory processes, but that these processes were dissociated. We further found evidence for lateralisation of anticipatory temporal but not spatial processes. This indicates that distinct mechanisms may drive automatic spatial and temporal extrapolation of upcoming events from rhythmic event streams. This contrasts with previous findings that instead suggest an interaction between spatial and temporal attention processes when endogenously driven. Our results further highlight the need for isolating intentional from unintentional processes for better understanding the various anticipatory mechanisms engaged in processing behaviourally relevant stimuli with predictable spatio-temporal structure such as motion and speech.     

Dominance and neophobia in coyote (Canis latrans) breeding pairs

Previous research suggests that within social animals, subordinate individuals are less neophobic than dominant individuals. We investigated the effect of social status on neophobic responses using 10 captive coyote breeding pairs. Social status was determined from observations of feeding behavior and agonistic interactions during a series of reference trials. Once dominance was established, we surrounded an experimental area with novel stimuli (ropes adorned with interspersed flags) to create a novel context around a familiar food source. Contrary to hypotheses, dominant coyotes were first to feed, showed more interest toward novel stimuli, and eventually crossed the barrier, which subordinates never did. Our results indicate that dominant coyotes are less neophobic of novel settings that contain familiar food than subordinates are. Since a reduction in neophobia can be interpreted as an increase in risk taking, our results support previous observations that dominant (alpha) coyotes take more risks than subordinates. Our results also suggest reasons for differential observations of coyote behavior in the field: artificial selection against bold behavior in populations undergoing predator control.     

Quantifying individual variation in the propensity to attribute incentive salience to reward cues

If reward-associated cues acquire the properties of incentive stimuli they can come to powerfully control behavior, and potentially promote maladaptive behavior. Pavlovian incentive stimuli are defined as stimuli that have three fundamental properties: they are attractive, they are themselves desired, and they can spur instrumental actions. We have found, however, that there is considerable individual variation in the extent to which animals attribute Pavlovian incentive motivational properties ("incentive salience") to reward cues. The purpose of this paper was to develop criteria for identifying and classifying individuals based on their propensity to attribute incentive salience to reward cues. To do this, we conducted a meta-analysis of a large sample of rats (N = 1,878) subjected to a classic Pavlovian conditioning procedure. We then used the propensity of animals to approach a cue predictive of reward (one index of the extent to which the cue was attributed with incentive salience), to characterize two behavioral phenotypes in this population: animals that approached the cue ("sign-trackers") vs. others that approached the location of reward delivery ("goal-trackers"). This variation in Pavlovian approach behavior predicted other behavioral indices of the propensity to attribute incentive salience to reward cues. Thus, the procedures reported here should be useful for making comparisons across studies and for assessing individual variation in incentive salience attribution in small samples of the population, or even for classifying single animals.     

Collective Action in Action: Prosocial Behavior in and out of the Laboratory

ABSTRACT  Experiments have become a popular method to study altruism and cooperation in laboratory and, more recently, in field settings. However, few studies have examined whether behavior in experiments tells us anything about behavior in the "real world." To investigate the external validity of several common experimental economics games, we compare game behavior with prosocial behavior among Tsimane forager-horticulturalists of lowland Bolivia. We find that food-sharing patterns, social visitation, beer production and consumption, labor participation, and contributions to a feast are not robustly correlated with levels of giving in the economics games. Payoff structure and socioecological context may be more important in predicting prosocial behavior in a wide variety of domains than stable personality traits. We argue that future experimental methods should be tailored to specific research questions, show reduced anonymity, and incorporate repeat measures under a variety of conditions to inform and redirect ethnographic study and build scientific theory. [Keywords: altruism, cooperation, experimental economics, Tsimane]     

The Importance of Demonstratively Restoring Order

Contrary to what is often assumed, order is not the strongest context for encouraging normative behavior. The strongest context effect on normative behavior comes from cues that clearly convey other people’s respect for norms. Ironically, this show of respect necessitates some contrasting disrespect that is being restored. Using civic virtues (such as helping behavior) as a prototype of normative behavior, the three field experiments described in this paper reveal the impact of normative cues on civic virtues. Results show that the strongest effect on making people follow prosocial norms in public places emanates from seeing order being restored, rather than just order being present. The robust and surprisingly large effects show that observing other people’s respect for one particular norm (as evidenced in their restoring physical order) makes it more likely that the onlooker follows other norms as well. This implies that prosocial behavior has the highest chance of spreading when people observe order being restored. There are clear policy implications: create low cost “normative respect cues” wherever it is desirable to increase conformity to norms.     

Preschool Children’s Behavioral Tendency toward Social Indirect Reciprocity

Social indirect reciprocity seems to be crucial in enabling large-scale cooperative networks among genetically unrelated individuals in humans. However, there are relatively few studies on social indirect reciprocity in children compared to adults. Investigating whether young children have a behavioral tendency toward social indirect reciprocity will help us understand how and when the fundamental ability to form cooperative relationships among adults is acquired. Using naturalistic observation at a nursery school, this study examined whether 5- to 6-year-olds show a behavioral tendency to engage in social indirect reciprocity in response to their peers’ prosocial behavior toward a third party. The results revealed that bystander children tended to display prosocial behavior toward their peers more frequently after observing these peers’ prosocial behavior toward third-party peers, compared with control situations; this suggests that 5- to 6-year-olds may have an essential behavioral tendency to establish social indirect reciprocity when interacting with peers in their daily lives. In addition, bystanders tended to display affiliative behavior after observing focal children’s prosocial behavior. In other words, observing peers’ prosocial behavior toward third-party peers evoked bystanders’ positive emotions toward the helpers. Considering both the present results and previous findings, we speculate that in preschoolers, such positive emotions might mediate the increase in the bystander’s prosocial behavior toward the helper. In addition, an intuitional emotional process plays an important role in the preschooler’s behavioral tendency toward social indirect reciprocity in natural interactions with peers.     

The sense of agency is action–effect causality perception based on cross-modal grouping

Sense of agency, the experience of controlling external events through one''s actions, stems from contiguity between action- and effect-related signals. Here we show that human observers link their action- and effect-related signals using a computational principle common to cross-modal sensory grouping. We first report that the detection of a delay between tactile and visual stimuli is enhanced when both stimuli are synchronized with separate auditory stimuli (experiment 1). This occurs because the synchronized auditory stimuli hinder the potential grouping between tactile and visual stimuli. We subsequently demonstrate an analogous effect on observers'' key press as an action and a sensory event. This change is associated with a modulation in sense of agency; namely, sense of agency, as evaluated by apparent compressions of action–effect intervals (intentional binding) or subjective causality ratings, is impaired when both participant''s action and its putative visual effect events are synchronized with auditory tones (experiments 2 and 3). Moreover, a similar role of action–effect grouping in determining sense of agency is demonstrated when the additional signal is presented in the modality identical to an effect event (experiment 4). These results are consistent with the view that sense of agency is the result of general processes of causal perception and that cross-modal grouping plays a central role in these processes.     

Affective Balance,Team Prosocial Efficacy and Team Trust: A Multilevel Analysis of Prosocial Behavior in Small Groups

Little research has focused on how individual- and team-level characteristics jointly influence, via interaction, how prosocially individuals behave in teams and few studies have considered the potential influence of team context on prosocial behavior. Using a multilevel perspective, we examined the relationships between individual (affective balance) and group (team prosocial efficacy and team trust) level variables and prosocial behavior towards team members. The participants were 123 students nested in 45 small teams. A series of multilevel random models was estimated using hierarchical linear and nonlinear modeling. Individuals were more likely to behave prosocially towards in-group members when they were feeling good. Furthermore, the relationship between positive affective balance and prosocial behavior was stronger in teams with higher team prosocial efficacy levels as well as in teams with higher team trust levels. Finally, the relevance of team trust had a stronger influence on behavior than team prosocial efficacy.     

Sensory Basis of Food Detection in Wild <Emphasis Type="BoldItalic">Microcebus murinus</Emphasis>

Very little is known about how nocturnal primates find their food. Here we studied the sensory basis of food perception in wild-caught gray mouse lemurs (Microcebus murinus) in Madagascar. Mouse lemurs feed primarily on fruit and arthropods. We established a set of behavioral experiments to assess food detection in wild-born, field-experienced mouse lemurs in short-term captivity. Specifically, we investigated whether they use visual, auditory, and motion cues to find and to localize prey arthropods and further whether olfactory cues are sufficient for finding fruit. Visual cues from motionless arthropod dummies were not sufficient to allow reliable detection of prey in choice experiments, nor did they trigger prey capture behavior when presented on the feeding platform. In contrast, visual motion cues from moving prey dummies attracted their attention. Behavioral observations and experiments with live and recorded insect rustling sounds indicated that the lemurs make use of prey-generated acoustic cues for foraging. Both visual motion cues and acoustic prey stimuli on their own were sufficient to trigger approach and capture behavior in the mouse lemurs. For the detection of fruit, choice experiments showed that olfactory information was sufficient for mouse lemurs to find a piece of banana. Our study provides the first experimental data on the sensory ecology of food detection in mouse lemurs. Further research is necessary to address the role of sensory ecology for food selection and possibly for niche differentiation between sympatric Microcebus species.     

Who Are You More Likely to Help? The Effects of Expected Outcomes and Regulatory Focus on Prosocial Performance

Prosocial behavior refers to a broad category of actions that benefit other people or the society. Compared with other factors that affect prosocial performance, prosocial outcomes, consisting of prosocial gains and prosocial non-losses have received less attention up to now. In the current research, we explored the influences of different types of expected outcomes and regulatory focus on prosocial performance. Studies 1a and 1b examined the differences in prosocial performance elicited by prosocial gain (e.g., enhancing others’ access to clean water) and prosocial non-loss outcomes (e.g., protecting others from suffering dirty water). We found that the expected prosocial non-loss outcomes induced greater prosocial performance compared with the expected prosocial gain outcomes. Studies 2a and 2b examined the effects of dispositional and situational regulatory focus on prosocial loss aversion. We found that differences in prosocial performance between two expected prosocial outcomes were reduced when promotion focus was primed; whereas a primed prevention focus did not significantly increase this difference. Additionally, participants displayed a greater prosocial loss aversion in the prevention focus condition than in the promotion focus condition. The reason for the non-significant interaction between regulatory focus and expected prosocial outcome was discussed.     

Decision-Making under Ambiguity Is Modulated by Visual Framing,but Not by Motor vs. Non-Motor Context. Experiments and an Information-Theoretic Ambiguity Model

A number of recent studies have investigated differences in human choice behavior depending on task framing, especially comparing economic decision-making to choice behavior in equivalent sensorimotor tasks. Here we test whether decision-making under ambiguity exhibits effects of task framing in motor vs. non-motor context. In a first experiment, we designed an experience-based urn task with varying degrees of ambiguity and an equivalent motor task where subjects chose between hitting partially occluded targets. In a second experiment, we controlled for the different stimulus design in the two tasks by introducing an urn task with bar stimuli matching those in the motor task. We found ambiguity attitudes to be mainly influenced by stimulus design. In particular, we found that the same subjects tended to be ambiguity-preferring when choosing between ambiguous bar stimuli, but ambiguity-avoiding when choosing between ambiguous urn sample stimuli. In contrast, subjects’ choice pattern was not affected by changing from a target hitting task to a non-motor context when keeping the stimulus design unchanged. In both tasks subjects’ choice behavior was continuously modulated by the degree of ambiguity. We show that this modulation of behavior can be explained by an information-theoretic model of ambiguity that generalizes Bayes-optimal decision-making by combining Bayesian inference with robust decision-making under model uncertainty. Our results demonstrate the benefits of information-theoretic models of decision-making under varying degrees of ambiguity for a given context, but also demonstrate the sensitivity of ambiguity attitudes across contexts that theoretical models struggle to explain.