Page 188 - Emotions through the eyes of our closest living relatives- Exploring attentional and behavioral mechanisms

Chapter 8
contagion. Nevertheless, a third consideration for future work has to do with the link between yawning and emotion contagion is currently weak (Massen & Gallup, 2017). Emotion contagion requires having an emotional experience, but it is unclear what the emotional state underlying yawning might be. Yawning has been linked to boredom (see a discussion in Burn, 2017) as well as stress (Maestripieri et al., 1992; Paukner & Anderson, 2006). Moreover, some researchers argue that yawning is entirely unrelated to emotions and may simply be a form of motor mimicry (i.e., devoid of any emotional content; Yoon & Tennie, 2010). To establish whether yawn contagion is a proxy for emotion contagion, future research should aim to measure which emotional state, then, is transferred (Adriaense et al., 2020). This is of course not an easy feat as animals cannot report on their feelings, but one way to move forward is to study more closely the (social) contexts in which yawn contagion (or other examples of mimicry) occurs to determine whether it has a communicative purpose, and what that communicative purpose is.
A final methodological consideration concerns the use of the Pictorial Implicit Association Test (PIAT) for comparative research (Chapter 7). What research questions could comparative scientists answer using the PIAT, and which type of stimuli could be used? IATs are widely used in social cognitive research, for instance to study implicit associations with ethnicity or gender (e.g., Baron & Banaji, 2006; Nosek et al., 2002). Nevertheless, IATs could potentially help uncover the implicit associations underlying emotion perception in great apes.
Often, we have to make assumptions about valence and arousal of emotional signals in animals based on the contexts in which emotions are expressed and how individuals respond to them (Kret et al., 2020). However, we currently do not yet fully understand whether great apes view certain emotional expressions or scenes as positive or negative, or how they are perceived in terms of arousal. Moreover, human studies on emotion perception suffer from the same interpretive issues as animal studies, as human participants are often directly asked (e.g., through standardized questionnaires) about how they interpret emotional expressions or how they experience them. Notwithstanding the strong psychometric properties of some questionnaires, how individuals answer questions can be confounded by for instance the tendency to give desirable answers or their ability to self-reflect and articulate their emotions (Stone et al., 2000). For instance, individuals from clinical populations (e.g., autism-spectrum disorders) may find it challenging to report felt emotions or interpret them (Cook et al., 2013). Probing of implicit associations with emotions may therefore offer a less-biased way to measure how emotions are perceived, and also
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