How does drivers' visual search change as a function of experience? A systematic review and meta-analysis

Novice drivers are statistically over-represented in reported road crashes, with recent evidence suggesting that some of this increased crash involvement may be a result of limitations in their cognitive processing. Such processing has typically been measured by recording drivers' patterns of eye movements, however, the exact ways in which eye movements are reported and interpreted varies substantially between different studies in the literature. Therefore, the objective of this systematic review was to investigate whether novice drivers and experienced drivers do differ in clear and reproducible ways in their visual search. Studies were identified through searches of Web of Science, Medline, TRID Database, and the TRB Research in Progress Database, with no restrictions on publication status. Studies were included if they compared the visual search of a novice driver group (< 3 years driving experience) and an experienced driver group (> 3 years driving experience) using an eye tracking method and reported at least one of the following four visual search outcomes: fixation durations, horizontal spread of search, vertical spread of search and number of fixations. Two reviewers independently screened searches and assessed the full texts of potentially included studies. Of the 235 studies initially identified 18 were included in the review, with 13 studies reporting sufficient data to be included in the meta-analysis for at least one outcome measure. Given that the included studies deployed a range of method types, additional sub-group analyses were conducted using this factor. Sensitivity analyses were also conducted by temporarily removing extreme experience groups (e.g. driving instructors and learner drivers) in order to test the effect of different levels of experience and training. The meta-analyses, along with support from results discussed narratively, revealed that novice drivers have a narrower horizontal spread of search compared to experienced drivers, however, there were no overall differences in fixation durations, vertical spread of search or number of fixations when the studies were pooled together. These findings have important primary implications for the development of novice training interventions, with novice drivers needing to develop a broader horizontal spread of visual search, but not to necessarily learn to fixate further down the road. Subgroup analyses also provided considerations for future research studies in terms of the experience of the driver groups, and the method type used.