3. Neuropsychological Tests Verbal Estimation Task This task, modified from Barkley et al. (2001a), is to assess the length of participant's subjective temporal unit. First, the green circle is present on the central for several seconds then it will disappear. Subject is asked the duration of each target in 5, 12, 17, and 25 seconds. For each presentation in random, there are two trials rendering eight trials in total.