Executive functions refer to a range of higher-order cognitive functions that enable organized and goal-directed behavior. Problems manifested by two exemplary brain damaged patients help illustrate the role executive functions play in cognition and everyday life. The first example is patient A, who suffers brain damage in a traffic accident. In the hospital he seems to recover well. He is able to perform relatively well in standard intelligence quotient tests as well as in other tests that are used in clinical neuropsyhological examination, such as tests for memory and attention. Surprising problems emerge, however, during the weeks following release from hospital. Relatives soon begin to complain that the patient’s behavior seems impulsive and erratic, selling his luxurious home for few thousands, forgetting to pay items that he takes from the store, and ending up in quarrels with his friends and neighbours.
Another exemplary patient, here called patient B, suffers a stroke. After initial recovery he too shows surprisingly intact performance in standard clinical neuropsychological tests. It does not, however, take long before his relatives start complaining about what they describe as apathy and lack of initiative exhibited by the patient at home. He fails to initiate and carry through any behaviors on his own. However, if instructed and supervised through a sequence of behaviors such as preparing and eating breakfast he carries out the tasks without major problems. What these exemplary patient cases have in common is that both exhibit problems in executive functions that often follow from damage to the frontal lobes of the brain, especially to prefrontal cortical areas. Findings pertaining to this will be described in the following.