Baraud Isabelle, Buytet Bleuenn, Bec Philippe, Blois-Heulin Catherine
UMR 6552, University of Rennes 1, CNRS, Paimpont, France.
Behav Brain Res. 2009 Mar 17;198(2):449-58. doi: 10.1016/j.bbr.2008.11.032. Epub 2008 Nov 27.
Individuals in social groups monitor many relationships by adapting their activities to the sex, age, social status, behaviour as well as the position of conspecifics. Here, we investigated the influence of the relative positions of the members of two groups of mangabeys on social visual laterality (right/left) and 'transversality' (frontal/rear) in two contexts: (1) 'one-to-one' interactions and (2) a 'one-to-many' context allowing potential observation of all group members. We discuss our data in relation to (1) the influence of rank and (2) theories explaining lateralization of cerebral hemispheres. First, in 'one-to-one' situations, members of both groups were approached more frequently from their left than from their right, and red-capped mangabeys approached a group member more frequently from their right than from their left. In 'one-to-many' situations, red-capped mangabeys kept more group members in their right than their left frontal visual field. Conversely, the social 'transversality' bias was the same in both contexts: the frontal field was favoured. Second, approach side and relative positions differed according to social rank. Mangabeys that were approached more frequently from their left ranked relatively high. The higher an individual ranked, the more it left other group members behind it; on the contrary dominated mangabeys generally remained below other group members. Thus, social structures, as well as relationships within a group, appear to be good candidates to explain social laterality and 'transversality'.
社会群体中的个体通过调整自身活动以适应同种个体的性别、年龄、社会地位、行为以及位置，来监测多种关系。在此，我们研究了两组白眉猴群体成员的相对位置在两种情境下对社会视觉偏向（右/左）和“横向性”（前/后）的影响：（1）“一对一”互动；（2）“一对多”情境，在此情境下有可能观察到所有群体成员。我们结合（1）等级制度的影响和（2）解释大脑半球偏侧化的理论来讨论我们的数据。首先，在“一对一”情境中，两组成员被从左侧接近的频率都高于从右侧接近的频率，而红顶白眉猴从右侧接近群体成员的频率高于从左侧接近的频率。在“一对多”情境中，红顶白眉猴在其右视野中保留的群体成员比左视野中的更多。相反，两种情境下的社会“横向性”偏向是相同的：更倾向于前方视野。其次，接近方向和相对位置因社会等级而异。被从左侧更频繁接近的白眉猴等级相对较高。个体等级越高，它把其他群体成员落在身后的程度就越大；相反，处于从属地位的白眉猴通常落在其他群体成员之后。因此，社会结构以及群体内部的关系似乎是解释社会偏向和“横向性”的有力候选因素。
