Figure 2.

Mean RTs for (A) specified and (B) action‐selection conditions for the controls (grey squares) and PD groups (On = black triangles, Off = white triangles) across the age range. (C) Frequency of choices for the action‐selection condition, including repeating the previous selection, choosing the immediate neighboring finger to the previous selection or selecting a remote finger. A value of one indicates a true random selection, above one indicates a preference for that strategy, and below one indicates a tendency to suppress that strategy. The control subjects show a preference to not repeat the same finger choosing instead another finger, whereas patients in the “off” state show no preference but when in the “on” state they show a tendency to perseverate. (D) Frequency of repeats correlated with UPDRS score for patients when “on” and “off.” There is a significant trend of increasing perseveration with increasing disease severity.