Abstract
Declining cognitive and motor functions make safe driving difficult for older adults. Trail Making Test (TMT) scores are reported to facilitate the estimation of cognitive functions in older adults and enable correlations with parameters associated with driving skills and vehicle speed. However, the causal relationships between cognitive functions and discrete driving-related parameters remain unclear. First, this study examined the correlations between the TMT indices and driving-related parameters of older adult drivers. Next, it used structural equation modeling to express the causal relationships between the parameters and TMT indicators. Thirty older adult drivers accomplished an intersection passage task on a driving simulator (DS) and consecutively performed multiple TMT iterations. Vehicle operation data collected from DS logs, data on head motions to confirm safety at an intersection, and accumulated TMT scores indicating cognitive functions enabled this study to determine correlations between the TMT indices and the parameters of pedal operation (vehicle speed), steering (steering input and lateral vehicle position), and head motion (horizontal angle and velocity). Models were then created to discern relationships between these parameters and the cognitive functions of older adult drivers. The study results indicate the possibility of automatically estimating the cognitive functions of older adult drivers from their daily driving-related data.