Abstract Animal individuality is challenging to explain because individual differences are regulated by multiple selective forces that lead to unique combinations of characteristics. For instance, the study of personality, a core aspect of individuality, may benefit from integrating other factors underlying individual differences, such as lateralized cerebral processing. Indeed, the approach-withdrawal hypothesis (the left hemisphere controls approach behavior, the right hemisphere controls withdrawal behavior), may account for differences in boldness or exploration between left and right hemispheric dominant individuals. To analyze the relationships between personality and laterality we tested 80 male piglets with established laterality patterns for 2 motor functions (tail curling direction and the side of the snout used for manipulation) and a combined classification integrating both motor functions using cluster analysis. We analyzed basal salivary testosterone and cortisol along with their behavior in standardized tests as pre-established indicators of different personality traits (Boldness, Exploration, Activity, Sociability, and Coping). We found that the direction of the single motor biases showed significant associations with few personality traits. However, the combined laterality classification showed more, and more robust, significant associations with different personality traits compared with the single motor biases. These results supported the approach-withdrawal hypothesis because right-biased pigs were bolder and more explorative in a context of novelty. Additionally, right-biased pigs were more sociable than left-biased pigs. Therefore, the present study indicates that personality is indeed related to lateralized cerebral processing and provides insight into the multifactorial nature of individuality.

中文翻译：

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评估动物个性：猪个性与偏侧性之间的联系

摘要 动物个性难以解释，因为个体差异受多种选择力的调节，导致特征的独特组合。例如，作为个性的核心方面的人格研究可能受益于整合个体差异背后的其他因素，例如侧脑处理。事实上，接近退出假设（左半球控制接近行为，右半球控制退出行为）可能解释了左右半球主导个体之间的大胆或探索差异。为了分析性格和偏侧性之间的关系，我们测试了 80 头雄性仔猪，它们具有 2 种运动功能（卷尾方向和用于操作的鼻子侧面）的已建立的偏侧性模式，以及使用聚类分析整合两种运动功能的组合分类。我们分析了基础唾液睾酮和皮质醇以及它们在标准化测试中的行为，作为不同人格特征（大胆、探索、活动、社交和应对）的预先确定的指标。我们发现，单一运动偏差的方向与很少的人格特征显着相关。然而，与单一运动偏差相比，组合偏侧性分类显示出更多、更强大、与不同人格特征的显着关联。这些结果支持了退出假设，因为在新奇的背景下，偏右的猪更大胆、更具探索性。此外，偏右的猪比偏左的猪更善于交际。因此，本研究表明，个性确实与侧脑处理有关，并提供了对个性的多因素性质的洞察。