Executive function and the frontal lobes: A meta-analytic review

Currently, there is debate among scholars regarding how to operationalize and measure executive functions. These functions generally are referred to as "supervisory" cognitive processes because they involve higher level organization and execution of complex thoughts and behavior. Although conceptualizations vary regarding what mental processes actually constitute the "executive function" construct, there has been a historical linkage of these "higher-level" processes with the frontal lobes. In fact, many investigators have used the term "frontal functions" synonymously with "executive functions" despite evidence that contradicts this synonymous usage. The current review provides a critical analysis of lesion and neuroimaging studies using three popular executive function measures (Wisconsin Card Sorting Test, Phonemic Verbal Fluency, and Stroop Color Word Interference Test) in order to examine the validity of the executive function construct in terms of its relation to activation and damage to the frontal lobes. Empirical lesion data are examined via meta-analysis procedures along with formula derivatives. Results reveal mixed evidence that does not support a one-to-one relationship between executive functions and frontal lobe activity. The paper concludes with a discussion of the implications of construing the validity of these neuropsychological tests in anatomical, rather than cognitive and behavioral, terms.