One of the three main symptoms of ADHD is inattention. ADHD children are often accused (and sometimes guilty) of not paying attention and being easily distracted.

According to the DSM-IV (the most commonly used diagnostic criteria for ADHD), diagnostic criteria for impulsivity includes:

• Often fails to give close attention to details or makes careless mistakes in schoolwork, work, or other activities.
• Often has difficulty sustaining attention in tasks or play activities.
• Often does not seem to listen when spoken to directly
• Often does not follow through on instructions and fails to finish schoolwork, chores, or duties in the workplace (not due to oppositional behaviour or failure to understand instructions).
• Often has difficulty organising tasks and activities
• Often avoids, dislikes, or is reluctant to engage in tasks that require sustained mental effort (such as schoolwork or homework).
• Often loses things necessary for tasks or activities (e.g., toys, school assignments, pencils, books, or tools).
• Is often easily distracted by extraneous stimuli.
• Is often forgetful in daily activities.

What is important to understand is that most children are easily distractable and inattentive. Children with ADHD, however, display inappropriate levels of inattention and distactablity- constant and across settings (home, school, clinicians office,...). These children can never seen to stay on task.

As suggested above, inattention can lead to failure in finishing tasks. One famous example of this is the great Leonardo da Vinci. Although known for his painting, there are only 17 paintings (not drawings) that can be attributed to his 67 years as an artist, and some of these are incomplete. His tendency to leave projects unfinished reportedly resulted in Pope Leo X/s exasperated exclamation: "This man will never accomplish anything! He thinks of the end before the beginning" (Wallace, 1966, p.150).

Inattention is one of the three main symptoms of ADHD, the other two are: Hyperactivity and impulsivity.