  Before the era of fully automated vehicles, human is consistently an
indispensable part of the driving system. Various studies have investigated
drivers' cooperation with the vehicle under different conditions. In this
article, we analyzed how non-driving-related tasks (NDRT) influence takeover
time (TOT) by conducting a meta-analysis on 37 related papers. NDRTs were
transcoded into combinations of five basic dimensions to unify and demonstrate
their effects on drivers. In order to interpret experimental data
comprehensively, we implemented three methods. A synthetical analysis was
conducted to compare the effect size between each study and subgroup. Studies
with eligible control groups have been examined by the two-group analysis,
followed by moderator analysis on seven variables. The results from the
two-group analysis showed that both visual-mental-motoric and visual-mental
tasks have significant negative effects on the takeover time and the previous
type had a larger effect than the latter one. Moreover, the subgroup comparison
and meta-regression in the meta-analysis part revealed the correlation between
moderators and the effect size, in which the Driving Experience and the
Automation Level affected the relation between NDRT and TOT. The findings of
this paper can contribute to the improvement and new directions for further
scientific research and engineering design.
