Boys with Attention Deficit Hyperactivity Disorder (ADHD, N=50), Specific Learning Disorder (LD, N=45), combined Specific Learning Disorder and ADHD (LD/ADHD, N=25), and controls (N=51) completed effortful and automatic information processing tasks based on Treisman and Gelade's (1980) “information integration theory”. ADHD and LD/ADHD subjects did not differ from controls at baseline or under feedback and reward conditions, suggesting that they were investing similar levels of mental effort in the tasks. The LD group had a superior performance in the effortful task and an inferior performance in the automatic task compared with the other groups at baseline. The data suggest a potential method of distinguishing primary LD from learning difficulties that occur secondary to ADHD.