This test is very popular in assessing cognitive aspects of ADHD. Its main objective is analyzing the sustained attention as well as impulsivity. The Persian version of the test, which is computer based, has 150 Farsi digits which are considered as stimuli, out of which 30 stimuli (20%) are target stimuli and the remaining 80% are considered as nontarget stimuli. The interval between offering two stimuli is 500 ms and each stimulus is offered for 150 ms. The test period, considering the practical phase, which is carried out in order to enhance the subject's understanding before the main phase, is 200 s. Two types of errors are scored: omission and commission errors. The error of omission occurs when the subject fails to respond to the target stimulus indicating that the subject has had problem in understanding the stimulus, whereas the error of commission occurs when the subject responds to the nontarget stimulus. This reflects the deficiency in inhibiting the impulse. In this test, these two errors are counted by software. Correct responds and reaction time of the participant are also calculated. Reliability and validity of the Farsi version of CPT are reported in previous studies .