Intraindividual variability is a fundamental behavioural characteristic of aging but has been examined to a very limited extent in driving. This study investigated intraindividual variability in driving simulator measures in healthy drivers of different ages using the coefficient of variation (COV) as a variability measure. Participants were healthy volunteers who were regular drivers, who were divided into a “young” group, a “middle-aged” group, and an “old” group. They drove in two environments (rural, 72 drivers; urban, 60 drivers), under conditions of moderate and high traffic load, without and with distraction (conversation). Significant differences in COV were observed in the rural condition for headway distance and lateral position as a function of traffic load, with high traffic (without and with distraction) resulting in increased COV of headway and decreased COV of lateral position. Significant differences in COV were observed in the urban condition for headway distance only, with high traffic (without and with distraction) resulting in increased COV of headway. No age effects were found for any of the driving conditions. The results indicate that traffic load affected headway distance and lateral position in opposite directions in all three age groups: high traffic resulted in increased variability of headway in both rural and urban conditions but in decreased variability of lateral position in the rural conditions compared to moderate traffic irrespective of distraction. The study indicates that driving conditions affect the intraindividual variability of driving measures in selective ways, which may be linked to the extent of automatization of the driving variables and to adaptive changes to traffic condition challenges.

车内个体差异是衰老的基本行为特征，但在驾驶中受到了非常有限的检验。这项研究使用变异系数（COV）作为变异性量度，研究了不同年龄的健康驾驶员在驾驶模拟器测量中的车内个体变异性。参与者是健康的志愿者，他们是常规驾驶员，分为“年轻”组，“中年”组和“老年”组。他们在中等和高交通负荷的条件下，在没有干扰和有干扰的情况下（对话）在两种环境中行驶（农村72位驾驶员；城市60位驾驶员）。在农村地区，车距和横向位置随交通负荷的变化，观察到COV的显着差异，交通流量大（无干扰和分散注意力）会导致车头行驶的COV升高和侧向位置的COV降低。仅在车距范围内，在城市条件下观察到COV的显着差异，高流量（无干扰和有分心）导致车道COV增加。在任何驾驶条件下均未发现年龄影响。结果表明，在三个年龄段中，交通负荷都会影响相反方向的车距和横向位置：与中等交通量相比，高交通流量导致农村和城市条件下车距变化的增加，但农村条件下横向位置变化的减小不管分心。研究表明，驾驶条件会选择性地影响驾驶措施的个体差异，