Temporal Dynamics of Event-Related Potentials in Visual Perceptual Decision-Making

Perceptual decision-making slows with advancing age, but the specific neural mechanisms underlying this decline remain unclear. In this study we investigated whether age-related slowing stems from a specific impairment in the evidence accumulation process, indexed by the centroparietal positivity (CPP) event-related potential. Younger (18-35 years, n=30) and older (60-85 years, n=30) adults performed a random dot motion discrimination task while EEG was recorded. Participants were subdivided into "Fast" and "Slow" responders based on median reaction times within their age group. While older adults showed overall slower reaction times and reduced CPP amplitudes, the fundamental relationship between CPP buildup rate and decision speed was preserved across age groups. In both younger and older adults, faster responders exhibited a significantly steeper CPP slope than slower responders. These results indicate that evidence accumulation remains functionally intact in healthy aging. Slower decisions are primarily associated with a less efficient accumulation process rather than a change in decision threshold. This suggests that interventions targeting the efficiency of sensory evidence integration could help mitigate age-related cognitive slowing.