Higher cognitive functions refer to the highest level of human intellectual functioning, including formation, reasoning, and executive functions. The executive functions can be conceptualized as having four components ; volition, planning, purposive action, and effective performance. Because higher cognitive functions represent the most advanced stages of intellectual development, they are often highly susceptible to the effects of brain injuries and mental disorders. The ability to perform effectively within the environment is determined in large part by an individual's adequacy in performing such higher-order function. Especially executive functions are necessary for appropriate, socially responsible, and effectively sell-serving adult conduct. Therefore, an assessment of the psychiatric patient's performance in these areas will provide useful diagnostic information, as well as information concerning social and vocational prognosis.