Spatial frequency as a critical modulator: How oxytocin and facial expressions jointly affect cuteness perception of infant faces.

Cuteness plays a vital role in facilitating parent-child bonding and prosocial behavior. However, few studies have examined cuteness perception from the perspective of visual information processing mechanisms. The current study employed spatial frequency (SF) as an experimental probe to investigate how stimulus-driven factor (infant facial expressions) and perceiver-dependent factors (observers' oxytocin) influence cuteness perception using a subjective rating task. Present study employed a three-factor mixed experimental design, with SFs (broad SF, low SF and high SF) and facial expressions (positive, neutral and negative) as within-subjects variables, and oxytocin administration (24 IU oxytocin and placebo group) as a between-subjects variable. Subjective cuteness ratings were analyzed using linear mixed-effects modeling, incorporating experimental conditions as fixed effects (SFs, facial expression and oxytocin administration), gender as a covariate, and random effects for both participants and items. The results revealed that the effects of both oxytocin and facial expressions on cuteness perception were significantly modulated by SFs information. Notably, oxytocin elicited a statistically significant reduction in subjective cuteness ratings for low SF images (configural facial information), whereas no significant trend was observed for high SF images (detailed facial features). These findings suggest that cuteness perception represents an interactive process between stimulus characteristics and observer neurobiology, rather than a simple collection of static "cute features".