We have chosen to categorize executive functions into 12 separate but interrelated skills. There are numerous other conceptualizations of executive functioning, some of which describe a smaller but broader range of executive skills, such as those seen in the theories of Russell Barkley, Ph.D. and Thomas Brown, Ph.D. Other authors have described various executive skills that are supplemental to those that we use at LearningWorks for Kids. Some of these different conceptualizations of executive functions are presented in the following list, with brief definitions:

• Nonverbal working memory (maintaining mental information in the mind)

• The capacities for control and self-regulation (motor response, hindsight, retrospective and anticipatory thinking and actions)

• The ability to consider the future (to work out the consequences of one’s actions)

• Problem-recognition skills (the capacity to identify and solve problems)

• Fluency (as measured by efficient scanning, manipulation, and decision-making)

• The capacity to engage in independent, purposeful, and self-serving behaviors and to grasp the gist of a complex situation (goal-setting and decision-making)

• Hypothesis-generation and testing (as required in the scientific method)

• Common sense (the ability to apply one’s experience in new situations)

• Judgment and decision-making skills (the capacity to accurately appraise and analyze)

• The ability to take in all aspects of a situation and then integrate them in decision-making (perspective-taking and metacognition)

• Volitional skills and the capacity to formulate goals and form an intention (Self-directed behavior)

Russell Barkley’s model describes behavioral inhibition as the primary executive function in that it helps an individual to be able to think before acting and responding so that other executive functions can then be employed. These other executive functions include working memory, which allows one to move beyond the “here and now;” the ability to regulate affect and motivation, which impacts the control of one’s behaviors and emotions; the internalization of speech, which leads to metacognitive skills, planning words and concepts, and problem-solving; and reconstitution, the final phase, which allows an individual to recombine behaviors, thoughts, memories, and analyses in order to engage in appropriate problem-solving behaviors.

Barkley emphasizes the use of executive functions to guide behavior toward hypothetical future events. He describes Attention Deficit Hyperactivity Disorder as a performance disorder rather than a skill disorder. According to Barkley, it is not that an individual lacks the skills for planning, regulating his/her behavior, or sustaining his/her attention but that he/she has difficulty at the point of performing these behaviors. As a result, his recommendations are that interventions take place at this point of performance.

Thomas Brown, Ph.D. has developed a theory of executive skills in which he describes six clusters of cognitive functions. He describes each cluster as a basket containing a variety of related cognitive abilities. These clusters include activation (which involves organizing, prioritizing, and activating tasks), focus (which helps with sustaining and shifting attention), effort (which helps with sustaining energy and processing speed), emotion (which revolves around managing frustration and regulating feelings), memory (which involves utilizing one’s working memory and following directions), and action (which involves the ability to monitor and regulate one’s behaviors and actions). The theories of both Barkley and Brown suggest that deficits in executive functioning are core components of Attention Deficit Hyperactivity Disorders and relate to a number of other difficulties in learning and thinking skills. Brown describes Attention Deficit Hyperactivity Disorder as a developmental impairment, or delay, of executive functions that connect, prioritize, and integrate neural networks that manage the brain. He describes such executive functioning impairments as involving difficulties in slowing down and speeding up, shifting attention, and sustaining the focus necessary to complete a task.

A number of researchers have suggested that executive functions can be divided into hot and cold executive functions. Hot executive functions involve tasks with affective components, in which rewards and punishments are often present. Hot executive functions involve traits such as impulsivity and response inhibition. It is believed that these executive functions are centered in the orbital and prefrontal cortex of the brain. Cold executive functions are described as involving tasks that are mostly cognitive in nature. Examples of cold executive functions include working memory, sustained attention, and organization. These executive functions are presumed to be located in the brain’s dorsal lateral prefrontal cortex.

While a number of early theories suggested that executive functions solely involve the prefrontal cortex of the brain, recent data suggest that executive functions are part of a neural network that involves the prefrontal cortex, the cordate, the dorsal lateral cortex, and the hippocampus in the temporal lobe. Other areas of the network include the frontal lobes, the cerebellum, and the basal gangalia, which are all strongly linked. As a result of recent advances in using Functional Magnetic Resonance Imaging (FMRI) tests, executive functions are now increasingly being seen as constituting a major network in the brain, in which there exists multiple reciprocal connections and a great deal of complexity. Another perspective is to view the prefrontal cortex as being the final common pathway for managing information that comes from within the brain (internal-based information) and from external stimuli, such as that which comes from one’s environment.

Another conceptualization of executive functions is that they are psychological constructs that describe “how and whether” a person does something, not what he/she does, and that they involve the capacities to engage in independent and purposeful activity that may be self-serving. In contrast, Russell Barkley suggests that, rather than “how and whether,” executive functions involve the “when or whether” aspects of behavior.

Early conceptualizations of executive functioning suggested that such functions are static and preformed and conceived that the impact of the environment and training on executive function development is minimal. The Russian psychologist Luria (1973) described executive functioning as the ability to maintain an appropriate skill set in order to achieve a future goal. Alan Baddeley (1986) described executive functions as mechanisms by which performance is optimized in situations requiring simultaneous operation of a number of cognitive processes. Welsh and Pennington (1991) described executive functions as involving strategic planning, impulse control, organized search, and flexibility of thought and action. Martha Denckla (1989) described executive functioning as the ability to plan and sequence complex behaviors and simultaneously attend to multiple sources of information; her definition also included the ability to grasp the gist of complex situations, to resist distraction and interference, to inhibit inappropriate responses, and to sustain behavior for long periods of time.

Modern conceptualizations of executive functions point to the importance of personal experience and the environment. These views see the brain-basis of executive functions as being malleable in response to teaching, practice, and learning opportunities. This view, supported by modern neuroscience research, is consistent with the LearningWorks for Kids perspective, which views executive “skills” as capacities to engage in purposeful behavior rather than as fixed abilities in the brain.