Assessing the Relationship Between Emotion and Infant Sociomoral Evaluation Using Facial Electromyography (fEMG)

• In Event: Poster Session 12
  In Poster Session: PS 12 Topic - Moral Development

Abstract

Even young infants can discriminate between and differentially evaluate individuals based on numerous morally-relevant factors. For example, infants expect agents to selectively approach those who have helped versus harmed them in the past, and form social preferences for helpers over hinderers themselves (Hamlin et al., 2007; Hamlin & Wynn, 2011). But how do infants develop these preferences?

While several lines of work have explored the cognitive processes underlying infants’ sociomoral evaluations (for review, see Van de Vondervoort & Hamlin, 2018), we currently lack an understanding of whether/how emotion-based processes contribute to infants’ prosocial preferences. That said, a growing literature suggests an important link between emotion and moral judgment: Adults make harsher moral judgment after being induced to feel anger and disgust (e.g., Horberg et al., 2009), and children are more likely to deem novel actions impermissible if told that the actions elicit disgust (Rottman & Kelemen, 2012; Rottman et al., 2017). Neurological research further suggests that emotions play a crucial role in sociomoral evaluation early in development: When viewing displays of moral transgression, younger children show stronger activation in brain structures associated with emotion while older children show more activity in regions related to abstract reasoning (Decety, Michalska, & Kinzler, 2012).

Most relevant for the current study is recent work demonstrating that 7- and 22-month-olds express stronger positive emotions upon viewing prosocial versus antisocial events (Steckler et al., 2018). While this study had coders rate infants’ emotional reactions, the current study utilizes facial electromyography (fEMG), a more objective measurement tool capable of detecting even subtle muscle movements, to measure emotional expressions (Isomura & Nakano, 2016; Natale et al., 2013; Addabbo et al., 2019).

Thirty-three 7-month-olds viewed a live puppet show where a puppet, on alternating trials, is helped or hindered by another character (adapted from Hamlin & Wynn, 2011). Activation in the zygomaticus major (cheek, associated with smiling) and corrugator supercilii (brow, associated with frowning) muscles was measured and percent change from a selected baseline was calculated. A 2 (trial type: helping vs hindering) x 2 (muscle: brow vs cheek) x 4 (phase: four 2500ms bins following helping/hindering act) ANOVA revealed a significant three-way interaction between trial type, muscle, and phase (F(3,96) = 2.72, p < .05). Post-hoc tests revealed that infants showed elevated cheek (33.79%) versus brow (7.06%) activity following helping trials in the 2500 to 5000ms bin (t = -2.19, p = .03). These results are further supported by a permutation test designed to account for multiple comparison error rates (Maris & Oostenveld, 2007), which revealed a marginally significant effect of trial type for cheek activity from 2300ms to 2500ms post-action (p = .089).

Together, these results suggest that while these effects might be small, emotions may play an important role in early sociomoral evaluation: infants selectively displayed more positive emotions after viewing prosocial acts. Future work will increase the sample size (i.e., collecting an additional 15 infants, adjusting augmented-p appropriately; Sagarin et al. 2014) and conduct the study on an older population to explore these effects across development.

Authors

• Francis Yuen, University of British Columbia (UBC)
  Presenting Author

• Rachelle Graham, University of Western Ontario
  Non-Presenting Author

• Enda Tan, University of Maryland - College Park
  Non-Presenting Author

• Julia W Van De Vondervoort, University of Waterloo
  Non-Presenting Author

• J. Kiley Hamlin, University of British Columbia (UBC)
  Non-Presenting Author