Chimpanzees do not take into account what others can hear in a competitive situation

Chimpanzees (Pan troglodytes) know what others can and cannot see in a competitive situation. Does this reflect a general understanding the perceptions of others? In a study by Hare et al. (2000) pairs of chimpanzees competed over two pieces of food. Subordinate individuals preferred to approach food that was behind a barrier that the dominant could not see, suggesting that chimpanzees can take the visual perspective of others. We extended this paradigm to the auditory modality to investigate whether chimpanzees are sensitive to whether a competitor can hear food rewards being hidden. Results suggested that the chimpanzees did not take what the competitor had heard into account, despite being able to locate the hiding place themselves by the noise.     

发展中的行为决策研究

行为决策研究人们如何进行判断与选择。该学科希望能在描述决策的过程中帮助人们更好地进行决策,其研究的使命是促进和改善我们对人类决策行为的理解。在过去的1年里,中国科学院心理研究所行为决策课题组在社会与经济决策领域中已开展的研究包括：行为决策与脑、社会互动与决策、决策的文化差异、消费与投资的行为决策、效用最大化与幸福感。该文着重报告并讨论了我们在行为决策及其跨文化比较研究中的一些最新的主要发现     

Common marmosets (<Emphasis Type="Italic">Callithrix jacchus</Emphasis>) do not utilize social information in three simultaneous social foraging tasks

Social foraging is suggested to increase foraging efficiency, as individuals might benefit from public information acquired by monitoring the foraging activities of other group members. We conducted a series experiments with captive common marmosets (Callithrix jacchus) to investigate to what extent marmosets utilize social information about food location when foraging simultaneously with conspecifics. Subjects were confronted with dominant and subordinate demonstrators in three experiments which differed in the amount of information about food location available to the demonstrators. In all three experiments, the focal subjects’ performance in the social condition was not enhanced in comparison to a non-social control condition. Because we could rule out kleptoparasitism and aggressive displacements as explanations, we argue that the subjects’ tendency for scramble competition by avoiding others and dispersing over the foraging area seems to inhibit or mask the acquisition of social information about the location of rewarded patches.     

时间贴现的性质与脑机制

时间贴现是指个人对事件的价值量估计随着时间的流逝而下降的心理现象,它是行为选择理论的一个重要组成部分。着重介绍了时间贴现的数学模型（指数模型、双曲线模型族、非双曲线模型）、时间贴现现象和概率贴现现象的联系、延迟兑现与提前兑现时间贴现不对称现象及其理论解释,还讨论了时间贴现现象的神经机制研究。提出了时间贴现未来研究的几个主要问题     

Priorities of Global Justice

One-third of all human deaths are due to poverty-related causes, to malnutrition and to diseases that can be prevented or cured cheaply. Yet our politicians, academics, and mass media show little concern for how such poverty might be reduced. They are more interested in possible military interventions to stop human rights violations in developing countries, even though such interventions – at best – produce smaller benefits at greater cost. This Western priority may be rooted in self-interest. But it engenders, and is sustained by, a deeply flawed moral presentation of global economic cooperation. The new global economic order we impose aggravates global inequality and reproduces severe poverty on a massive scale. On any plausible understanding of our moral values, the prevention of such poverty is our foremost responsibility.     

Amount consumed varies as a function of feeder design.

Studies of pigeon behavior in which magazine-cycle duration is varied suggest that many researchers assume that feeders of different designs dispense food at roughly the same rate. However, Epstein (1981) showed that, with a commonly used feeder, the amount of grain a pigeon consumes is a negatively accelerated function of magazine-cycle duration. The present experiment shows that, with a different commonly used feeder, amount consumed is roughly a linear function of magazine-cycle duration. At a duration of 60 seconds, the second feeder dispenses roughly 10 times as much food as the first. Thus, reports of studies in which magazine-cycle duration is varied should identify the design of the feeder employed, and in some cases, authors should consider determining the feeding functions for those feeders.     

Positional Goods and the Social Rank Hypothesis: Income Inequality Affects Online Chatter about High‐ and Low‐Status Brands on Twitter

According to a social rank hypothesis, consumers who live in regions with higher income inequality will show greater interest in, and attention toward, positional goods and high‐status brands that serve a social signaling role. We analyze millions of posts on the microblogging platform Twitter for mentions of high‐ and low‐status brands. We find that luxury brands such as “Louis Vuitton” and “Rolex” are more frequently mentioned in tweets originating from US states, counties, and major metropolitan areas with higher levels of income inequality. In contrast, mentions of everyday brands such as “Walmart” or “Kmart” are more frequent in regions with a more equal distribution of income. Using sentiment analysis, we find higher valence (positivity) and arousal (excitement) for tweets that both mention high‐status brands and originate from regions with high levels of income inequality. These results corroborate the social rank hypothesis, showing that more psychological resources are allocated to positional consumption when the income gap between the rich and the poor is larger.     

Cognitive Load and the Equality Heuristic: A Two-Stage Model of Resource Overconsumption in Small Groups

Two studies were conducted to test a two-stage model of the psychological mechanisms underlying the overconsumption of scarce resources in small groups. The model proposes that members of groups sharing resources first anchor their consumption choices on an “equal-division” heuristic and then, given sufficient cognitive capacity, adjust their choices in a self-serving direction. The results from both studies support the model. The first study found that when faced with a common resource pool almost all group members expressed thoughts regarding equality; however, individuals with sufficient cognitive capacity requested more from the pool and expressed more task-relevant thoughts than individuals lacking the necessary cognitive resources. The second study provided additional support for the two-stage model by demonstrating that group members' cognitions occur in the order predicted by the model and by demonstrating that an individual difference, social value orientation, affects thought processes only when individuals are not experiencing high cognitive loads. Implications are discussed.     

Pilfering ravens, Corvus corax, adjust their behaviour to social context and identity of competitors

Like other corvids, food-storing ravens protect their caches from being pilfered by conspecifics by means of aggression and by re-caching. In the wild and in captivity, potential pilferers rarely approach caches until the storers have left the cache vicinity. When storers are experimentally prevented from leaving, pilferers first search at places other than the cache sites. These behaviours raise the possibility that ravens are capable of withholding intentions and providing false information to avoid provoking the storers' aggression for cache protection. Alternatively, birds may refrain from pilfering to avoid conflicts with dominants. Here we examined whether ravens adjust their pilfer tactics according to social context and type of competitors. We allowed birds that had witnessed a conspecific making caches to pilfer those caches either in private, together with the storer, or together with a conspecific bystander that had not created the caches (non-storer) but had seen them being made. Compared to in-private trials, ravens delayed approaching the caches only in the presence of storers. Furthermore, they quickly engaged in searching away from the caches when together with dominant storers but directly approached the caches when together with dominant non-storers. These findings demonstrate that ravens selectively alter their pilfer behaviour with those individuals that are likely to defend the caches (storers) and support the interpretation that they are deceptively manipulating the others' behaviour.This contribution is part of the special issue “Animal Logics” (Watanabe and Huber 2006).     

Infant food refusal and parental social support

The purpose of this study was to examine the relations between various aspects of social support and maternal and infant outcome variables in a group of families having infants showing food refusal compared to a control group. In the case of early food refusal, the results indicated that access to emotional support and satisfaction with support were related to maternal psychosomatic health. The relationships were interpreted as showing that social support has moderating effects on negative outcomes of food refusal.