Introduction

1. Coding is About Set Shifting not Speed Andrew S. Davis Eric E. Pierson Elizabeth L. Roberds Introduction The Coding subtests from the Wechsler scales are a commonly used portion of the Processing Speed Index. They are widely understood to measure incidental learning and visual attention. One psychometric strength of the subtest is their relatively high subtest specificity. This gives examiners confidence that they know what they are measuring. Recent research has suggested that other factors such as visual acuity, even when corrected, may also contribute to variance in this widely used task in certain populations (Davis et al., in press). The last decade has shown increasing interest in both research and practice into the relationship between executive functioning and other areas of cognitive processing. One component of executive functioning is cognitive set-shifting, sometimes referred to as mental flexibility. One measure of this is the Trail Making Test originally designed as part of the Army Individual Test Battery and later incorporated into the Halstead-Reitan Neuropsychological Test Battery (Reitan & Wolfson, 1993). In contrast to the high specificity of the Coding subtest, the Trail Making Test has been shown to have a variety of factors that contribute to performance on it. A partial list is motor speed, visual scanning, or letter or number sequencing. To help address this problem for several types of measures, as well as other concerns, the Delis-Kaplan Executive Function System (D-KEFS, Delis, Kaplan, & Kramer, 2001) was developed. One of the measures on the D-KEFS is a Trail Making Test that contains five conditions: Visual Scanning, Number Sequencing, Letter Sequencing, Number-Letter Sequencing (the cognitive set-shifting component), and Motor Speed. The purpose of this research was to explore the degree to which the various factors contributing to performance on the D-KEFS predict performance on the Coding subtest from the WAIS-III. Conclusions The results suggest that cognitive set-shifting is a requisite skill in completing the Coding task of the WAIS-III. Coding subtests require continual set shifting among different sets of stimuli (numbers to shapes) and a lack of mental flexibility may result in slow or error-filled performance. Coding subtests are also used to assess processing speed. Although the Coding test is timed, motor speed did not predict a substantial proportion of the variance. The other significant result from this analysis is the relationship between visual scanning and coding. Given the lack of a significant relationship with motor speed it would appear that Coding is more dependent upon the ability to search and locate information quickly as opposed to pure speed. Individuals with visual scanning deficits are likely to have academic problems when they need to quickly locate or isolate salient material (e.g., finding specific text on a page). It is also important to note that the number and letter sequencing tasks, measures of simple sequencing abilities that use time as the scoring criteria, were also not predictive of Coding performance. School psychologists are cautioned when analyzing the results of the coding subtest to consider the influence of executive functioning on this widely used task. Future research should investigate this finding with children. Linear Regression Results with the D-KEFS Trail Making Test as the Predictor Variables Methodology Participants were 64 (36 males and 28 females) college students in a large Midwestern university with a mean age = 19.89 years and a standard deviation = 3.63 years. Participants completed the D-KEFS Trail Making Test and Coding subtest from the Wechsler Adult Intelligence Scale-Third Edition (WAIS-III; Wechsler, 1997) as part of a larger research study. Results Linear regression analyses were conducted with each condition of the D-KEFS Trail Making Test serving as the predictor variable and the Coding subtest as the dependent variable. Results indicated that Visual Scanning was a significant predictor (R2 = .106; p = .009), Number Sequencing was not a significant predictor (R2 = .062; p = .052), Letter Sequencing was not a significant predictor (R2 = .026; p = .201), Letter-Number Sequencing was a significant predictor (R2 = .178; p = .001), and Motor Speed was not a significant predictor (R2 =.017; p = .300). • References • Davis, A. S., Hertza, J., Williams, R. N., Gupta, A. S., & • Ohly, J. (in press). The Influence of corrected visual acuity on visual attention and incidental learning in patients with multiple sclerosis. Applied Neuropsychology. • Delis, D. C. Kaplan, E., & Kramer, J. H., (2001). Delis • Kaplan Executive Function System: Examiner’s Manual. San Antonio, TX: The Psychological Corporation. • Reitan, R. M., & Wolfson, D. (1993). The Halstead-Reitan • Neuropsychological Test Battery. Tucson, AZ: Neuropsychology Press. • Wechsler, D. (1997). Wechsler Adult Intelligence Scales- • Third Edition. San Antonio, TX: Psychological Corporation. Presented at the 2010 National Association of School Psychologists Annual Convention, Chicago, IL