In the Day 2E, the participants were randomly assigned to two: Aggressive or Cautious conditions. This experiment measured the probability that the participants drove in front of another vehicle upon merging, which is defined as “lead probability.” The Day 2E was similar to 1E, except for the manipulation of the participants’ impression of the other vehicle as being aggressive/cautious via acceleration/deceleration of the other vehicle, and through the contents of the instructions regarding the other vehicle’s driving characteristics. In the Day 1E, they drove either on the merging lane or the main lane and merged lanes while considering the other vehicle driving along the adjacent lane. Two months after participating in Day 1E the participants joined Day 2E.

Twenty participants ( n male = 10 n female = 10 M age = 43.92 ) joined two experiments, Days 1E and 2E, using a driving simulator. This study examined how subjective information, specifically, a driver’s impression of the other vehicle, affects the decision to merge in front of or behind the other vehicle when merging lanes on a highway. In such driving situations, it is possible that people make decisions based not only on objective information, but also on subjective information. However, humans still must drive in complex situations, for instance, when merging lanes. In recent years, systems have been developed to realize automatic driving based on objective information such as the relative distance and relative speed between vehicles.

Driving impression