Page 63 - Emotions through the eyes of our closest living relatives- Exploring attentional and behavioral mechanisms

Attention towards humans’ and bonobos’ emotion
Introduction
Social animals, like humans and great apes, spend a considerable amount of their time
among conspecifics. In interactions with them, they produce, observe and exchange
emotional expressions. Because emotional expressions provide relevant information
and inform subsequent actions, they are efficiently processed; they readily attract the
attention of observers and are recognized easily (e.g., Ekman, 1984; Frijda et al., 1989).
The underlying mechanisms of producing and recognizing emotional expressions 3 are deeply grounded in our evolutionary past and it is therefore not surprising that
important parallels in emotion processing exist between humans and other great apes (Darwin, 1872; Kret et al., 2020). The majority of studies investigating emotion recognition and attentional biases toward emotions in humans has made use of isolated facial expressions as stimulus materials. However, emotions and facial expressions of emotion alike, are embedded in complex social scenes involving multiple individuals. Moreover, the literature is troubled with inconsistencies regarding gender (Kret & De Gelder, 2012a) and age differences (Van Rooijen et al., 2017). The goal of the current study was to assess the effect of naturalistic emotional scenes on the perception of emotional expressions. To address the aforementioned inconsistencies, we opted for a large community sample consisting of males and females and children as well as adults. Crucially, we compared the processing of scenes showing humans and apes in similar emotional scenarios to address the question of whether effects are human- emotion specific, or more generally linked to emotions and similar when observing emotions expressed by apes. Congruent findings across human and ape scenes would further support their shared evolutionary basis.
There is discussion in the human emotion literature about whether or not emotions and their expressions can be put into categories. Research showing that humans across the world can assign emotion labels to prototypical facial expressions suggests that such distinct categories exist (Ekman, 1984). However, contrasting literature shows that the same emotional expression can be interpreted differently based on context (Kret & De Gelder, 2010, 2012a, 2013; Kret & Straffon, 2018). Crucially, emotional expressions are perceived differently when posed by actors as compared to when real-life stimuli are employed (e.g., McLellan et al., 2010; Motley & Camden, 1988). Despite this evidence, the majority of studies has been using posed expressions, ignoring the fact that these prototypical expressions are not commonly observed in real life. For example, how often do we see the facial expression of fear? The smile, an expression that is common in real life, often gets the simplified label “happiness”
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