Page 19 - Emotions through the eyes of our closest living relatives- Exploring attentional and behavioral mechanisms

could be driven by highly salient, low-level perceptual characteristics of stimuli (for 1 instance the visibility of teeth, direct eye gaze, or simply their novelty) and therefore
reflect a more bottom-up process (Öhman et al., 2001a). Attention allocation can
also be driven by a top-down process that takes into account the motivations of the
observers, as well as the context the observers find themselves in (Victeur et al., 2020). Most likely, however, attention for emotions involves an interplay between bottom- up and top-down processes (Pessoa et al., 2006). Notwithstanding this debate, it is undisputed that expressions of emotion are automatically and swiftly attended to by humans. But is this attentional mechanism uniquely human, or can we find similar mechanisms in other animals?
Evidence for emotion-biased attention in animals is much more limited, and also mixed. Most of the work that exists is conducted with primates. One research task that can measure (implicit) selective attention towards emotions is the dot- probe task, which measures how fast individuals can touch a dot (i.e., the probe) on a screen after being presented with emotional and neutral stimuli (i.e., signals in the form of for instance a picture). Typically, individuals are faster at touching a dot when it is preceded by an emotional stimulus because emotions draw attention. Using the dot-probe task, Japanese macaque monkeys (Macaca fuscata) were found to have a threat-specific attentional bias (Masataka et al., 2018) that also extended to threatening facial expressions (Lacreuse et al., 2013; Parr et al., 2013). However, enhanced attention to threatening signals was not found in chimpanzees using the same paradigm (Kret et al., 2018; Wilson & Tomonaga, 2018). In contrast, bonobos showed biased attention towards more positively valenced emotional scenes. Finally, studies measuring attentional biases with eye-tracking have shown that chimpanzees and orangutans look longer at threatening stimuli such as fearful faces or aggressive interactions (Kano & Tomonaga, 2010a; Pritsch et al., 2017).
The mixed results show that more research is needed to close the knowledge gap on how expressions of emotion affect attention in other animals, especially given the importance of implicit measures of emotion processing for comparative research. The first part of this dissertation (Chapters 2 to 4) will therefore examine emotion-biased attention in humans and one great ape species, bonobos, in more detail (Figure 2a).
Spontaneous mimicry and emotion contagion
Attention allows for studying to what extent emotions can capture and hold interest, thus to a certain extent it elucidates whether emotions are meaningful to individuals. However, it does not inform us about whether emotions are meaningful for
The mechanisms of emotion perception
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