I have spent most of my professional career providing psychological services to children and adolescents.  During the early 1990’s, I found myself frustrated over the relatively meager advances, both empirically and theoretically, to the neuropsychological understanding of developmental disorders.  I was particularly dissatisfied with the practice of conceptualizing childhood disorders, such as attention-deficit/hyperactivity disorder (ADHD), as a “set” or “list” of specific behavioral symptoms with minimal attention to developmental factors.

     The exceptional research and theorization of Joaquin Fuster in The Prefrontal Cortex (1989) helped crystallize for me the role of the prefrontal cortex in the generation, organization, and evaluation of complex human behavior, both healthy and disturbed.  Unfortunately, at this point our understanding of the relationship of prefrontal functioning to childhood behavior was limited, in part, due to the traditional neuropsychological view of the frontal lobes as “silent” structures until late adolescence/early adulthood.  Subsequent research has challenged this view by revealing the emergence of frontal/executive functions early in childhood that follow a protracted trajectory to maturity in adulthood.  Moreover, advances in neuroimaging have identified, and continue to identify, anatomical and functional differences in the brains of children with ADHD and other childhood disorders relative to healthy children.

     Executive planning provided a potential heuristic for integrating and understanding the diverse behaviors of childhood disorders, particularly ADHD.  Accordingly, I set out to find a measure sensitive to executive planning for children.  My search led to Shallice’s Tower of London (1982).  Unfortunately, the measure had been developed for adult patients with frontal lobe damage.  Adaptions of the Tower of London and normative data for children were not available at this time.  As a consequence, I decided to modify and standardize the Tower of London.  My association with Dr. Zillmer of Drexel University revealed the need to include adults, in addition to children and adolescents, in the standardization sample.  Multi-Health Systems agreed to assist in providing normative data, and subsequently recruited a significant number of children, adolescents, and adults for assessment.  The Tower of London-Drexel University (TOL^DX) reflects the culmination of these events.    

     The TOL^DX consists of a Technical Manual, two tower structures (each with a set of beads) and Record Forms (Child and Adult).  The measure presents 10 problems of ascending difficulty that require from 3 to 7 moves to solve.  The examinee is asked to match a presented bead configuration while adhering to two specific rules.  The TOL^DX takes approximately 15 minutes to administer and is well tolerated by examinees due to its brevity, novelty, and game-like appeal.  Seven scoring variables, representing different, although overlapping aspects of executive planning and problem solving, are provided.  Normative data is available for children and adults ranging in age from 7 to 60+ years.  Principles for interpreting the scoring variables, both qualitatively and quantitatively, are outlined for children and adults.  Preliminary studies of the psychometric characteristics of the TOL^DX are supportive of its reliability and validity.  The TOL^DX  can be obtained from Multi-Health Systems, Inc.