Investigating visual search mechanisms and enhancing the diagnostic potential of the trail making test using eTMT

The Trail Making Test (TMT) is a complex task involving visual search and is widely used to assess various cognitive functions. While existing literature often emphasizes task switching, the nuances of visual search within the TMT remain debated. In this study, we developed a new digital version of the TMT, the eTMT, to more effectively analyze visual search performance dynamics. We hypothesized that critical aspects of visual search, particularly the display set-size effect, have been overlooked in prior research — specifically the impact of distractors in the visual field on participants’ performance. Additionally, we explored how the line drawn by participants in the traditional paper-and-pencil version may influence performance. To test these hypotheses, we conducted two experiments (data collected in 2022). The first involved modifying the standard TMT by removing the connecting line between targets and turning reached targets into black discs. In the second experiment, we introduced variations such as having reached targets disappear entirely and altering their positions, alongside adjustments to the spatial relationships between successive targets. Our findings confirm the significant influence of the display set-size effect on TMT performance, providing insights into the mechanisms underlying visual search and underscoring the potential of the digitally redesigned TMT for improved assessment.