Impression formation in the human infant brain

Abstract

<p>Forming an impression of another person is an essential aspect of human social cognition linked to medial prefrontal cortex (mPFC) function in adults. The current study examined the neurodevelopmental origins of impression formation by testing the hypothesis that infants rely on processes localized in mPFC when forming impressions about friendly versus threatening individuals. Infants’ brain responses were measured using functional near-infrared spectroscopy (fNIRS) while watching four different individuals displaying either smiles or frowns directed toward or away from them (N = 77). This was followed by a person preference test measured by looking behavior using eyetracking. Our results show that infants’ mPFC responses distinguish between friendly and threatening faces when directed at them and that these responses predicted their person preference. This demonstrates that the mPFC is involved in impression formation in human infants, attesting to the early ontogenetic emergence of brain systems supporting person perception and adaptive behavior.</p>

Simplicity and validity in infant research

“…Whereas a smile would be inappropriate in an antisocial interaction, failing to smile in a prosocial interaction might itself be odd. Given that infants readily distinguish different emotional expressions from early in life (Grossmann, Striano, & Friederici, 2007;Walker-Andrews, 1997) and form impressions of human agents who previously smiled versus frowned (Krol & Grossmann, 2020), it is possible that they would notice any differential facial expressions presented by human agents and use these, rather than the construct of interest, to evaluate the agents in the study. Although researchers could simply have all human experimenters maintain a neutral expression throughout their interactions (e.g., Schmidt & Sommerville, 2011), or control for the overall amount of each emotion across interaction type (e.g., Buon et al, 2014), doing so in a way that does not itself threaten validity can be difficult to achieve.…”