Brandimarte, L., Vosgerau, J., & Acquisti, A. (2018). Differential discounting and present impact of past information. Journal of Experimental Psychology: General, 147(1), 74-92. http://dx.doi.org/10.1037/xge0000372
Abstract: How does information about a person’s past, accessed now, affect individuals’ impressions of that person? In 2 survey experiments and 2 experiments with actual incentives, we compare whether, when evaluating a person, information about that person’s past greedy or immoral behaviors is discounted similarly to information about her past generous or moral behaviors. We find that, no matter how far in the past a person behaved greedily or immorally, information about her negative behaviors is hardly discounted at all. In contrast, information about her past positive behaviors is discounted heavily: recent behaviors are much more influential than behaviors that occurred a long time ago. The lesser discounting of information about immoral and greedy behaviors is not caused by these behaviors being more influential, memorable, extreme, or attention-grabbing; rather, they are perceived as more diagnostic of a person’s character than past moral or generous behaviors. The phenomenon of differential discounting of past information has particular relevance in the digital age, where information about people’s past is easily retrieved. Our findings have significant implications for theories of impression formation and social information processing.
Friday, February 9, 2018
Reciprocal altruism among non-human animals is much more widespread than currently assumed: rats in Norway trade food and services
Reciprocal Trading of Different Commodities in Norway Rats. Manon K. Schweinfurth, Michael Taborsky. Current Biology, https://doi.org/10.1016/j.cub.2017.12.058
Highlights
• Norway rats reciprocally trade food for allogrooming, and vice versa
• Experimental proof of tit-for-tat-like exchange of different services in animals
• The study suggests that reciprocal commodity trading in animals may be common
Summary: The prevalence of reciprocal cooperation in non-human animals is hotly debated [1, 2]. Part of this dispute rests on the assumption that reciprocity means paying like with like [3]. However, exchanges between social partners may involve different commodities and services. Hitherto, there is no experimental evidence that animals other than primates exchange different commodities among conspecifics based on the decision rules of direct reciprocity. Here, we show that Norway rats (Rattus norvegicus) apply direct reciprocity rules when exchanging two different social services: food provisioning and allogrooming. Focal rats were made to experience partners either cooperating or non-cooperating in one of the two commodities. Afterward, they had the opportunity to reciprocate favors by the alternative service. Test rats traded allogrooming against food provisioning, and vice versa, thereby acting by the rules of direct reciprocity. This might indicate that reciprocal altruism among non-human animals is much more widespread than currently assumed.
Highlights
• Norway rats reciprocally trade food for allogrooming, and vice versa
• Experimental proof of tit-for-tat-like exchange of different services in animals
• The study suggests that reciprocal commodity trading in animals may be common
Summary: The prevalence of reciprocal cooperation in non-human animals is hotly debated [1, 2]. Part of this dispute rests on the assumption that reciprocity means paying like with like [3]. However, exchanges between social partners may involve different commodities and services. Hitherto, there is no experimental evidence that animals other than primates exchange different commodities among conspecifics based on the decision rules of direct reciprocity. Here, we show that Norway rats (Rattus norvegicus) apply direct reciprocity rules when exchanging two different social services: food provisioning and allogrooming. Focal rats were made to experience partners either cooperating or non-cooperating in one of the two commodities. Afterward, they had the opportunity to reciprocate favors by the alternative service. Test rats traded allogrooming against food provisioning, and vice versa, thereby acting by the rules of direct reciprocity. This might indicate that reciprocal altruism among non-human animals is much more widespread than currently assumed.
Rolf Degen summarizes: Contrary to earlier believes, humans have at least as many - if not more - Olfactory Receptor genes as monkeys and apes, with color vision being no limiting factor
Evolution of Genes for Color Vision and the Chemical Senses in Primates. Shoji Kawamura, Amanda D. Melin. Chapter in Evolution of the Human Genome I. https://link.springer.com/chapter/10.1007/978-4-431-56603-8_10
Abstract: Primates are generally regarded as visually oriented mammals, trading a sense of smell for good sight. However, recent studies have questioned this simplistic view, and it is not well understood the extent to which senses have evolved interactively or in concert with each other in primates including humans. For example, the number of olfactory receptor genes is not as clearly differentiated between species with different color vision as once asserted. Among senses, receptors of stimuli for vision, olfaction, and bitter/sweet/umami tastes all belong to the G-protein-coupled receptor (GPCR) family, for which the genetic mechanism of signal perception is well understood. Thus, it is now possible to explore the evolutionary correlation among different senses in primates by studying these receptor groups for interspecies divergence, intraspecies diversity, and functional differences among variants. In this chapter, we review recent findings on these receptors and senses in humans and other primates and discuss the future directions of studies on their sensory evolution.
[Screenshot from https://twitter.com/DegenRolf/status/961876566023143424]
Abstract: Primates are generally regarded as visually oriented mammals, trading a sense of smell for good sight. However, recent studies have questioned this simplistic view, and it is not well understood the extent to which senses have evolved interactively or in concert with each other in primates including humans. For example, the number of olfactory receptor genes is not as clearly differentiated between species with different color vision as once asserted. Among senses, receptors of stimuli for vision, olfaction, and bitter/sweet/umami tastes all belong to the G-protein-coupled receptor (GPCR) family, for which the genetic mechanism of signal perception is well understood. Thus, it is now possible to explore the evolutionary correlation among different senses in primates by studying these receptor groups for interspecies divergence, intraspecies diversity, and functional differences among variants. In this chapter, we review recent findings on these receptors and senses in humans and other primates and discuss the future directions of studies on their sensory evolution.
[Screenshot from https://twitter.com/DegenRolf/status/961876566023143424]