Age-related positivity bias in emotional processing: Investigating its neural correlates across early and automatic processing stages

Emotional processing differs systematically across the adult lifespan, with older adults demonstrating a preference for positive stimuli, known as the positivity effect. However, it remains unclear whether this effect depends on controlled processing or can also emerge at early, automatic stages of emotional processing. The present study addressed this question using a deviant–standard–reverse oddball paradigm combined with event-related potentials (ERPs) and sliding-window representational similarity analysis (RSA). Younger and older adults were presented with schematic faces, in which neutral faces served as standard stimuli and happy or sad faces served as deviants, while attention was directed to a central task. Neural responses were indexed by the N170 component and expression mismatch negativity (eMMN), reflecting early perceptual processing and automatic change detection, respectively. The results revealed a clear age-related dissociation in emotional bias. Younger adults showed enhanced neural responses to sad deviants, whereas older adults showed enhanced responses to happy deviants. Critically, this pattern was observed at both early perceptual stages (N170) and later automatic stages (eMMN). These findings suggest that the positivity effect in aging is not limited to controlled processing but extends to automatic stages of emotional processing, supporting the view that age-related emotional biases may be partly driven by automatic emotion regulation mechanisms.