Infants Time Their Smiles to Make Their Moms Smile

One of the earliest forms of interaction between mothers and infants is smiling games. While the temporal dynamics of these games have been extensively studied, they are still not well understood. Why do mothers and infants time their smiles the way they do? To answer this question we applied methods from control theory, an approach frequently used in robotics, to analyze and synthesize goal-oriented behavior. The results of our analysis show that by the time infants reach 4 months of age both mothers and infants time their smiles in a purposeful, goal-oriented manner. In our study, mothers consistently attempted to maximize the time spent in mutual smiling, while infants tried to maximize mother-only smile time. To validate this finding, we ported the smile timing strategy used by infants to a sophisticated child-like robot that automatically perceived and produced smiles while interacting with adults. As predicted, this strategy proved successful at maximizing adult-only smile time. The results indicate that by 4 months of age infants interact with their mothers in a goal-oriented manner, utilizing a sophisticated understanding of timing in social interactions. Our work suggests that control theory is a promising technique for both analyzing complex interactive behavior and providing new insights into the development of social communication.     

蒙古人与蒙古马

蒙古马是世界多个马科类的一种,很早以前就生活在中亚北部广阔的草原。世界上除了蒙古马以外,还有很多种马。这些马种从身个到神态,乃至其习性都有很大的差异。蒙古马这一称谓源于蒙古人与它们赖以生存的蒙古草原。蒙古马与蒙古人最早结缘。     

Children and Their Pets

Abstract

This study examines the frequency of pet possession and its covariation with family variables (family size, housing conditions, parents' employment, maternal support) among elementary school children. Additionally, children's pet caring activities and their emotional relationship to pets were investigated. Subjects were 426 fourth graders (213 boys, 213 girls). Results indicate that pets are very frequently present in families, with the dog as the most common and most preferred animal. Parents' employment and maternal support do not covariate with pet possession, but housing conditions do. The child-pet relationship depends on childrens' gender, pet type and status of ownership (child vs. family). The intensity of pet caring is mainly related to pet type and ownership, whereas the quality of emotional contact depends on pet type and childrens' gender. On the background of manifold articles reporting case studies and educational, respectively clinical counseling experiences the discussion emphasizes the need for sound empirical research on the relationship between personality characteristics and pet ownership.     

Great Spotted Cuckoos Frequently Lay Their Eggs While Their Magpie Host is Incubating

Species that suffer from brood parasitism face a considerable reduction in their fitness which selects for the evolution of host defences. To prevent parasitism, hosts can mob or attack brood parasites when they approach the host nest and block the access to the nest by sitting on the clutch. In turn, as a counter‐adaptation, brood parasites evolved secretive behaviours near their host nests. Here, we have studied great spotted cuckoo (Clamator glandarius) egg‐laying behaviour and defence by their magpie (Pica pica) hosts inside the nest using continuous video recordings. We have found several surprising results that contradict some general assumptions. The most important is that most (71%) of the parasitic events by cuckoo females are completed while the magpie females are incubating. By staying in the nest, magpies force cuckoo females to lay their egg facing the high risk of being attacked by the incubating magpie (attack occurred in all but one of the events, n = 15). During these attacks, magpies pecked the cuckoo violently, but could never effectively avoid parasitism. These novel observations expand the sequence of adaptations and counter‐adaptations in the arms race between brood parasites and their hosts during the pre‐laying and laying periods.     

New Unnatural L-Nucleoside Enantiomers:From Their Stereospecific Synthesis to Their Biological Activities

Abstract

Several purine and pyrimidine β-L-dideoxynucleosides were stereospecifically synthesized and their antiviral properties examined. Two of them, namely β-L-2′,3′-dideoxyadenosine (β-L-ddA) and its 2′,3′-didehydro derivative (β-L-d4A) were found to have significant anti-human immunodeficiency virus (HIV) and anti-hepatitis B virus (HBV) activities in cell culture.