The Impact of Billboards on Driver Visual Behavior: A Systematic Literature Review

<b>Objective:</b> External distraction appears to affect at least 6–9% of distraction-affected motor vehicle collisions. Billboards may be good models for studying external distraction in general, and it is also desirable to understand billboard-related distraction per se. However, there has not yet been a clear consensus on the scope of billboard-related distraction or its dynamics with respect to characteristics of drivers, billboards, traffic, and the roadway. To narrow these knowledge gaps, a systematic literature review was conducted on billboard-related changes in driver visual behavior. <b>Methods:</b> A systematic literature search yielded 443 results, of which 8 studies met all inclusion criteria. Five studies meeting all inclusion criteria were later identified and added. Results were analyzed in terms of 4 categories of visual behavior: (1) gaze variability (GV), glance pattern activity (GPA), and percentage of time spent glancing at the forward roadway; (2) glances at unexpected drive-relevant stimuli; (3) glances at expected drive-relevant stimuli; and (4) glances at billboards. <b>Results:</b> There was considerable evidence that about 10–20% of all glances at billboards were ≥0.75 s, that active billboards drew more glances and more long glances (≥0.75 s, ≥2.0 s) than passive billboards but did not attract a longer average glance, and that there was large variability among individual billboards within categories (e.g., active vs. passive). The extent to which billboards attracted glances ≥ 2.0 s was uncertain. There was tentative evidence that billboards did not affect GPA, glances at expected drive-relevant stimuli, or the proportion of time drivers spent glancing at the forward roadway and that they did affect vertical GV and glances at unexpected drive-relevant stimuli. <b>Conclusions:</b> Generally, billboard-related distraction appeared to be minor and regulated by drivers as the demands of the driving task changed. However, this review's findings suggest that this may not be true in all cases. Future research should emphasize the tails of the distribution in addition to average cases, in terms of both the analysis of visual behavior and the complexity of driving tasks. Further research is also needed to understand the effects of billboard design, driver characteristics, and road and traffic context.<b>研究目标：</b> 外部分心至少会导致6%至9%的涉及分心的机动车碰撞事故。广告牌通常可作为研究外部分心的优质模型，同时也有必要深入理解广告牌相关分心问题本身。然而，目前学界尚未就广告牌相关分心的研究范畴，以及其随驾驶员、广告牌、交通与道路特征变化的作用机制达成明确共识。为填补这些认知空白，本研究针对广告牌引发的驾驶员视觉行为变化开展了系统性文献综述。 <b>研究方法：</b> 本次系统性文献检索共得到443条结果，其中8项研究符合全部纳入标准，后续又补充识别并纳入5项符合标准的研究。本研究从4类视觉行为维度对结果展开分析：(1) 注视变异性（Gaze Variability, GV）、扫视模式活跃度（Glance Pattern Activity, GPA）以及注视前方道路的时间占比；(2) 对意外驾驶相关刺激的扫视；(3) 对预期驾驶相关刺激的扫视；(4) 对广告牌的扫视。 <b>研究结果：</b> 现有充分证据表明，针对广告牌的全部扫视中，约10%至20%的时长≥0.75秒；动态广告牌比静态广告牌能吸引更多扫视以及更多次的长时扫视（≥0.75秒、≥2.0秒），但并未使平均扫视时长更长；且同类广告牌（如动态与静态组）之间的个体差异显著。广告牌引发时长≥2.0秒扫视的影响程度尚未明确。现有初步证据显示，广告牌不会对扫视模式活跃度、预期驾驶相关刺激扫视，或驾驶员注视前方道路的时间占比产生影响，但会对垂直注视变异性以及意外驾驶相关刺激扫视产生影响。 <b>研究结论：</b> 总体而言，广告牌相关分心的影响程度较轻，且会随着驾驶任务需求变化由驾驶员自行调控。但本次综述的结果表明，这一结论并非适用于所有场景。未来研究在视觉行为分析与驾驶任务复杂度考量方面，除关注平均案例外，还应着重分析分布的极端值情况。此外，还需开展进一步研究以明确广告牌设计、驾驶员特征，以及道路与交通环境的影响效应。