Quaresmini Caterina, Forrester Gillian S, Spiezio Caterina, Vallortigara Giorgio
Center for Mind/Brain Sciences, University of Trento.
Department of Psychology, University of Westminster.
J Comp Psychol. 2014 Aug;128(3):276-84. doi: 10.1037/a0036355. Epub 2014 Apr 21.
The influence of the social environment on lateralized behaviors has now been investigated across a wide variety of animal species. New evidence suggests that the social environment can modulate behavior. Currently, there is a paucity of data relating to how primates navigate their environmental space, and investigations that consider the naturalistic context of the individual are few and fragmented. Moreover, there are competing theories about whether only the right or rather both cerebral hemispheres are involved in the processing of social stimuli, especially in emotion processing. Here we provide the first report of lateralized social behaviors elicited by great apes. We employed a continuous focal animal sampling method to record the spontaneous interactions of a captive zoo-living colony of chimpanzees (Pan troglodytes) and a biological family group of peer-reared western lowland gorillas (Gorilla gorilla gorilla). We specifically focused on which side of the body (i.e., front, rear, left, right) the focal individual preferred to keep conspecifics. Utilizing a newly developed quantitative corpus-coding scheme, analysis revealed both chimpanzees and gorillas demonstrated a significant group-level preference for focal individuals to keep conspecifics positioned to the front of them compared with behind them. More interestingly, both groups also manifested a population-level bias to keep conspecifics on their left side compared with their right side. Our findings suggest a social processing dominance of the right hemisphere for context-specific social environments. Results are discussed in light of the evolutionary adaptive value of social stimulus as a triggering factor for the manifestation of group-level lateralized behaviors.
社会环境对偏侧化行为的影响现已在多种动物物种中得到研究。新证据表明，社会环境可以调节行为。目前，关于灵长类动物如何在其环境空间中导航的数据很少，而且考虑个体自然环境的研究也很少且零散。此外，关于是只有右脑还是左右脑都参与社会刺激的处理，尤其是情绪处理，存在相互竞争的理论。在这里，我们首次报告了由大猩猩引发的偏侧化社会行为。我们采用连续焦点动物取样方法，记录了圈养在动物园的一群黑猩猩（黑猩猩）和一个由同伴抚养的西部低地大猩猩生物家族群体（西部低地大猩猩）的自发互动。我们特别关注焦点个体更喜欢让同种个体保持在身体的哪一侧（即前、后、左、右）。利用新开发的定量语料库编码方案，分析显示黑猩猩和大猩猩都表现出在群体层面上，焦点个体显著倾向于让同种个体位于其前方而非后方。更有趣的是，两组在群体层面上也都表现出一种偏向，即与右侧相比，更喜欢让同种个体在其左侧。我们的研究结果表明，在特定情境的社会环境中，右脑在社会处理方面占主导地位。我们根据社会刺激作为群体层面偏侧化行为表现触发因素的进化适应性价值对结果进行了讨论。
