Extreme levels of mental fatigue lead to an inability to perform regular tasks and irritability. Studies that require participants to carry out attention-demanding tasks under conditions of high distraction reveal how unpleasant a mentally fatigued person can be. After exposure to such an experience, individuals are less likely to help someone in need. They are also more aggressive, less tolerant, and less sensitive to socially important cues. Fatigue that is experienced by participants of these kinds of studies is induced by attention-intensive tasks, and the observed effects of such fatigue are correlated with decline in inhibitory control. Signs of Directed Attention Fatigue include temporarily feeling unusually distractible, impatient, forgetful, or cranky when there is no associated illness. In more severe forms, it can lead to bad judgment, apathy, or accidents, and can contribute to increased stress levels.