The trail less traveled: Analytical approach for creating shortened versions for virtual reality-based color trails test.

The Color Trails Test ("CTT") is among the most popular neuropsychological assessment tests of executive function, targeting sustained visual attention (Trails A), and divided attention (Trails B). During the pen-and-paper (P&P) test, the participant traces 25 consecutive numbered targets marked on a page, and the completion time is recorded. In many cases, multiple assessments are performed on the same individual, either under varying experimental conditions or at several timepoints. However, repeated testing often results in learning and fatigue effects, which confound test outcomes. To mitigate these effects, we set the grounds for developing shorter versions of the CTT (<25 targets), using virtual reality (VR) based CTT (VR-CTT). Our aim was to discover the minimal set of targets that is sufficient for maintaining concurrent validity with the CTT including differentiation between age groups, and the difference between Trails A and B. To this aim, healthy participants in three age groups (total  = 165; young, middle-aged, or older adults) performed both the P&P CTT, and one type of VR-CTT (immersive head-mounted-device VR, large-scale 3D VR, or tablet). A subset of 13 targets was highly correlated with overall task completion times in all age groups and platforms ( > 0.8). We tested construct validity and found that the shortened-CTT preserved differences between Trails A and B ( < 0.001), showed concurrent validity relative to the P&P scores ( > 0.5;  < 0.05), and differentiated between age groups ( < 0.05). These findings open the possibility for shortened "CTT-versions", to be used in repeated-measures experiments or longitudinal studies, with potential implications for shortening neurocognitive assessment protocols.