Cannabis, also known as marijuana, contains the active ingredient tetra-hydrocannabinol (THC) that creates sedation, mild euphoria, and in large amounts, changed time and sensation perceptions may occur. Physical dependence and withdrawal symptoms are not present in marijuana use as well as any long-term marked adverse or toxic effects according to most studies. There is no set association between intoxication and violence because for most users, aggression is actually inhibited with use. At-risk individuals, on the other hand, may use marijuana and experience a lack of inhibitions and no self-control leading to impulsive aggression. Short-term wise, the user will unknowingly experience impairment in complex perceptual/motor tasks. An exception to these studies is one study that showed marijuana users experiencing impairment in mental flexibility, abstractions, and learning.