I have no idea how the quoted test was formatted, but a twitch reaction when a subject is prepared for it within a short time-frame (10s like this website) will

I have no idea how the quoted test was formatted, but a twitch reaction when a subject is prepared for it within a short time-frame (10s like this website) will be much faster than a test where the subject rests or is made to focus on another task for longer periods between sampling. Also, It sounds like that particular sample was from a cohort of stroke victims, perhaps the stroke also affected their reaction times, or stroke victims represent a generally older demographic and have slower reaction times outright than the younger cohort a website might be measuring.