Tower test of Delis-Kaplan Executive Function Scale (D-KEFS)

The D-KEFS Tower test [30] requires multiple fundamental cognitive skills and higher-level executive functions. Key fundamental abilities measured by this test include visual attention and visual spatial skills. Executive functions assessed by this test include the following:

Spatial planning, or the ability to mentally visualize the outcome of making 2 or moves before they are made;

Rule learning, or the ability to acquire heuristic strategies for building towers using the fewest numbers of moves possible (e.g., the ability to learn the best method for clearing a small disk off of a peg to place a bigger disk on the peg);

Inhibition, or the ability to refrain from impulsive behavior and to use trial and error to formulate spatial plans or to learn effective problem-solving strategies; and

Establishing and maintaining cognitive set, or the capacity to learn the instructional rules to perform a task and to apply those rules consistently while solving each problem.

The overall performance on all the above-mentioned tests for the cognitive components of EF (Similarities, Block design, Picture arrangement, Arithmetic, Coding, and D-KEFS Tower test) was judged according to the age-standard scores, with a mean of 10 (SD: 3).