Hyperkinetic people display disorganized, poorly controlled and excessive activity; they lack perseverance in tasks involving thought and attention, and tend to move from one activity to the next without completing any. They are frequently accident-prone, reckless and impulsive, and may thoughtlessly (rather than defiantly) break rules. Cognitive impairment and delayed language and motor development are more common in this group than in the general population; and they may experience low self-esteem and engage in dis-social behavior as a consequence of the disorder.