Executive Control

Executive control (EC) refers to cognitive processes that control goal-directed behavior. As the word control suggests, EC is a higher order process because it exerts control over other cognitive processes. In this respect, the work done by EC can be compared to that of a chief executive officer or orchestra conductor. Similar to these, EC has a leadership role and is situated on top of a hierarchy. It is crucial for decision-making, goal setting, planning how to accomplish the goal, assigning tasks and duties to other cognitive processes, monitoring, performance evaluation, and, if necessary, correction of any of the steps along the process of goal attainment.

EC, however, is recruited only in particular situations. For many everyday situations, we do not need EC because we can rely on well-rehearsed actions or habits. Basically, we can successfully manage many everyday tasks while running on autopilot. For example, we do not need to exert a lot of mental effort to make coffee in the morning, find our way to work, or solve basic addition problems. EC becomes necessary when we face new situations in response to which we have to come up with new solutions while at the same time not falling back into habitual ways of responding. For example, EC would be required if the coffee machine broke down and we had to find an alternative way to satisfy our caffeine cravings or if the regular route we take to work is closed due to construction and we had to plan out a different route. In these situations, EC takes over and regulates our actions.

Historically, EC is rooted in research on consequences of damage to the prefrontal cortex, which is an area of the brain located in the front part of the frontal lobes. Compared to other animals, the prefrontal cortex is relatively large in humans and takes up approximately 30% of the brain. Damage [Page 801]to the prefrontal cortex can have multiple consequences and, depending on the specific site of damage, results in deficits in the performance of complex everyday tasks, personality changes, and social disinhibition and impulsivity. Although many brain regions contribute to EC, the prefrontal cortex is considered to be the area of the brain that is crucial for EC.

Psychologists have created many tasks to assess EC in a controlled manner. In one widely used task, the Wisconsin Card Sorting test, the participant is presented with target cards that differ on the dimensions of color, shape, and number. For example, the target cards might be one red circle, two green stars, three blue squares, and four yellow crosses. Then the participant is shown one test card (e.g., two red crosses) that matches several target cards on one dimension. The task of the participant is to match the test card to the correct target card, without being told how to do this. Thus, the participant has to find out the rule according to which the experimenter wants the cards to be sorted. For example, if the cards are supposed to be sorted by number, then the test card with the two red crosses must be placed next to the target card with the two green stars. After the participant has placed the test card, the experimenter tells the participant whether the card has been placed correctly. For example, if cards were supposed to be sorted by number and the participant placed the tested card displaying two red crosses with the target card showing four yellow crosses (assuming that the sorting rule was by shape), the experimenter would say, incorrect. Using the experimenter’s feedback, the participant is in a position to figure out the sorting rule after a number of trials. Once the participant has sorted the cards correctly for a number of trials, the experimenter, unbeknownst to the participant, changes the sorting rule (e.g., from number to shape), and the participant must discover the new sorting rule. One way to measure EC skills is to count the number of perseverative errors, that is, the number of times a participant places test cards according to the previous sorting rule (e.g., number) even after the sorting rule has been changed (e.g., shape). Perseverative errors are thought to indicate the level of one’s ability to shift attention to a new sorting dimension while inhibiting attention to the old, reinforced sorting dimension. Perseverative errors are common in adults with lesions to particular (dorsal) parts of the prefrontal cortex. Research has demonstrated large decreases in perseverative errors on the Wisconsin Card Sorting test between 5 years and 11 years, smaller improvements up to the age of 14 years, and an increase in perseverative errors between 25 years and 70 years.

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