Page 126 - Emotions through the eyes of our closest living relatives- Exploring attentional and behavioral mechanisms

Chapter 5
by-product of increased arousal during these contexts. If this were the case, we would expect increased chances of scratch contagion during tense contexts regardless of the relationship quality and whether the triggering scratch was seen or not. This was not the case (see Figure 2). As such, it seems unlikely that the increased contagion observed in our study is a by-product of higher scratch rates induced by tension, but that it is truly an effect of the context and the relationship quality between the expresser and observer.
In conclusion, this study is the first to provide evidence for the presence of scratch contagion in the orangutan, possibly suggesting a case of emotional contagion. We show that scratch contagion is stronger between weakly bonded individuals when there is tension, demonstrating that it has a possible social function. Our results are relevant for future research on mimicry and its link with emotional contagion as they highlight that contagion is not simply stronger between individuals with a high relationship quality, as is commonly suggested. Furthermore, the variety of contexts in which self-scratching is observed throughout the literature highlight the complexity of this behavior and the mechanism underlying its contagious effect. Importantly, the degree of scratch contagion may depend on the interaction between contextual factors and social relationships.
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