Demuru Elisa, Ferrari Pier F, Palagi Elisabetta
Dipartimento di Bioscienze, Università di Parma, Parma, Italy,
Anim Cogn. 2015 Jan;18(1):333-44. doi: 10.1007/s10071-014-0804-6. Epub 2014 Sep 10.
Great apes show very complex systems for communicating emotions and intentions. Whereas gestures are intentional signals, facial expressions can disclose both emotions and intentions. The playful context is a good field to explore the possible dichotomy between intentionally and emotionally driven signals as it has been suggested that one of its functions is to learn producing and decoding communicative patterns. To understand how signals are produced during play and how they are modified in the course of ontogeny, we investigated the use of playful facial expressions and gestures in bonobos (Pan paniscus), a tolerant species showing a high propensity to play even as adults. Our results showed that the use of play faces and gestures is strongly influenced by the characteristics of the play session. Both play faces and gestures were more often performed when social play involved physical contact and when the receiver was visually attending, thus suggesting that both signals can be strategically employed when communicating becomes more urgent. Compared to play faces, gestures were more frequent during dyadic than polyadic sessions, when a unique receiver was involved. Being gestures not context specific, they are probably used more selectively by the sender. On the contrary, play faces are context specific and transmit an unequivocal positive message that cannot be misconceived. These features legitimize a broad use of playful facial expressions, independently of the number of playmates. The similarities and differences in the production of these signals are probably linked to the different degree of emotionality and intentionality characterizing them.
大猩猩表现出非常复杂的情感和意图交流系统。手势是有意的信号，而面部表情既能揭示情感又能传达意图。嬉戏情境是探索有意驱动信号和情感驱动信号之间可能存在的二分法的良好领域，因为有人认为其功能之一是学习产生和解读交流模式。为了了解在嬉戏过程中信号是如何产生的以及它们在个体发育过程中是如何变化的，我们研究了倭黑猩猩（Pan paniscus）嬉戏时面部表情和手势的使用情况，倭黑猩猩是一种宽容的物种，即使成年后也有很高的嬉戏倾向。我们的结果表明，嬉戏面部表情和手势的使用受到嬉戏过程特征的强烈影响。当社交嬉戏涉及身体接触且接收者在视觉上关注时，嬉戏面部表情和手势出现的频率更高，这表明当交流变得更加紧迫时，这两种信号都可以被策略性地运用。与嬉戏面部表情相比，在二元嬉戏（涉及唯一接收者）过程中，手势比在多元嬉戏过程中更频繁。由于手势不依赖于特定情境，发送者可能会更有选择性地使用它们。相反，嬉戏面部表情依赖于特定情境，并传递一种明确无误的积极信息，不会被误解。这些特征使得嬉戏面部表情能够被广泛使用，而与玩伴数量无关。这些信号产生过程中的异同可能与它们所具有的不同程度的情感性和意向性有关。
