People with ADHD (Attention Deficit Hyperactivity Disorder) often have problems with their perception of time but it is unclear whether this is due to difficulties in estimating how much time has elapsed or by the fact that they become distracted by other things. A team of researchers from Taipei looked into this issue in a study of 258 children aged between 10 and 17, 168 of whom had ADHD. In one task children had to press a button for the same length of time that a green circle was lit up on a screen. In another task the children did the same thing but had to count numbers while they estimated the time. The children with ADHD were worse at estimating the time in both tasks but their performance grew worse as the task got more complicated suggesting that attention played a more important part than time perception per se.
Hwang, Shoou-Lian ... [et al] - Deficits in interval timing measured by the dual-task paradigm among children and adolescents with attention-deficit/hyperactivity disorder Journal of Child Psychology and Psychiatry March 2010, 51(3), 223-232