The DVT, included in Robert K. Heaton's expanded HRB normative system, is a simple task designed to measure vigilance during rapid visual tracking and accurate selection of target stimuli. It is sensitive to subtle changes in neuropsychological status, but relatively insensitive to the effects of either repeated administrations or practice. The DVT appears to isolate alertness and vigilance while placing minimal demands on two other components of attention: selectivity and capacity.

The materials consist of a new Professional User's Guide, the Test Booklet, and a set of 4 color-coordinated Scoring Keys. Respondents are asked to find and cross out either 6s (standard administration) or 9s (alternate administration), which appear randomly within 59 rows of single digits. These 59 rows of digits are printed in red on the first stimulus page and in blue on the second.

Time to complete the task is recorded using a stopwatch. The 4 scoring templates (one for 6s and one for 9s in each of the colors) allow the test administrator to count and record errors of commission and omission. Administration and scoring can be accomplished by individuals with no formal training under the supervision of a qualified psychologist. Interpretation within the context of a comprehensive neuropsychological evaluation requires training in clinical psychology or neuropsychology. Normative data are not provided in the Professional User's Guide, but are presented in Comprehensive Norms for an Expanded Halstead-Reitan Battery.