Interval Timing Task

This experiment includes 139 subjects: 94 individuals with Parkinsons disease,
and 45 controls. Subjects completed this IntervalTiming task (along with multiple other cognitive tasks)
while EEG was recorded with a 64-channel BrainVision cap. This task presented black instructional
text on the center of a white screen that read "Short interval" on 3-second interval trials
and "Long interval" on 7-second interval trials. The researchers never communicated the actual
interval durations to the patient. The instructions were displayed for 1 second, and the appearance
of an image of a solid box in the center of the computer screen indicated the start of the interval.
The cue was displayed on the screen for the entire trial, which lasted 6 s for 3-s intervals and
14 s for 7-s intervals. The researchers instructed participants to press the keyboard spacebar
when they judged the target interval to have elapsed. Participants were directed not to count, and
a distractor vowel appeared at random intervals in the screen center.