Social modeling of eating and the mirror neuron system: the role of neurophysiological mechanisms in predicting susceptibility to modeling

Abstract

The social modeling of eating effect refers to the consistently demonstrated phenomenon that individuals tend to match the quantity of their food intake to their eating companion. The current study aimed to explore the mirror neuron system (MNS) as a causal mechanism through which this effect may occur. Factors demonstrated to enhance MNS activity were additionally explored as moderators. The current study thus aimed to examine whether: (1) external eating moderated social modeling of eating as mediated by MNS activity, (2) external eating was associated with attentional bias to food, and (3) attentional bias towards food moderated the indirect modeling effect. Under the guise of rating empathy, 93 female undergraduates at Lakehead University viewed a female video confederate “incidentally” consume either a low or high intake of chips while electroencephalogram (EEG) activity was recorded. Subsequent ad libitum potato chip consumption was quantified. Neither external eating nor attentional bias towards food moderated the hypothesized indirect social modeling of eating effect. An exploratory first- and second-stage dual moderation model, however, revealed that frontal asymmetry and body mass index (BMI) moderated an indirect effect. Left frontal asymmetry was associated with greater mu activity and a positive association between model and participant chip consumption, while right frontal asymmetry was associated with less mu activity and a negative association. Across all levels of frontal asymmetry, the effect was only significant among those with a BMI at the 50th percentile or lower. Thus, among leaner individuals, the MNS mediated social modeling of eating, as moderated by frontal asymmetry. Left frontal asymmetry enhanced MNS activity and subsequent modeling, while right frontal asymmetry attenuated MNS activity and led to a reversal of the effect.