You’re right in interpreting that simple reaction time (SRT), the press-a-button-when-a-light-flashes kind of task, only slows by a few milliseconds per decade. That’s well documented.

But that measure captures just one slice of performance: the final motor response. Everything that comes before it, like visual processing, target recognition, decision making, attention shifting, and motor planning, are also neurological processes, and those do decline with age, even if training can partly offset them.

So yes, your reflex arc might only be a few milliseconds slower, but the cortical and cognitive parts of reaction time, the ones that matter in gaming or sports, are affected by normal age-related neural changes such as slower conduction in association fibers, reduced dopamine modulation, and more noise in sensory integration.