Page 83 - Emotions through the eyes of our closest living relatives- Exploring attentional and behavioral mechanisms

Attention towards humans’ and bonobos’ emotion
(Duka & Townshend, 2004), which shows that even a brief learning episode might already influence attention mechanisms.
When zooming in on conspecific scenes, the results show that humans’
attention was mostly captured by scenes showing sex and yawns. This is partly in
line with our earlier study in bonobos where strongest effects were observed in
scenes depicting yawns, grooming, and sex (in that order) (Kret et al., 2016). Can
we conclude from this that humans are even more attuned to sex than the hyper-
sexual bonobo? Unfortunately, we cannot, due to a limitation of this study. That 3 is, the human sexual scenes were standing out from the rest of the images as only
that category showed half-naked people. We could not circumvent this problem
in the current study as alternative approaches had other drawbacks. For instance,
it is difficult to have completely neutral images showing nudes. Even more tricky
is to find other emotional scenes showing emotional expressions (e.g., a group of
aggressive nudes). That said, future studies should address this confound by using
a stimulus category showing nudes in at least relatively neutral poses. The fact that
out of all stimulus categories, human adults rated the category sex as most arousing
and most positive makes such a follow-up even more appealing.
Conclusion
Based on participants’ explicit valence and arousal ratings and on their attentional biases toward certain stimulus categories, we can conclude that overall, humans perceive emotional scenes showing people similarly as emotional scenes of bonobos. Especially because this finding was observed in lay people who rarely see bonobos, this effect cannot be explained by learning, but likely reflects a shared evolutionary origin in these expressions themselves.
Some expressions have more communicative potential than others. The smile or the bared teeth display are examples of clear signals, meant for conspecifics to be seen. These expressions can have multiple meanings which can be interpreted correctly within the specific context. We found that children may still need to learn to use these contextual cues when judging a situation as positive or negative.
The sex scenes were rated very positively, especially by male participants. Even though they rated these more positively than women, their attention was captured similarly, by far surpassing all other emotion categories. It is interesting that this sex
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