This study investigates the influence of the complexity of in-car written road information messages on drivers' performances. An experimental car was fitted with a micro-computer and the equipment required to convey different road information messages and record data. During the experimental procedure the drivers had to read each in-car road information message once and to memorize it. The independent variable has taken into account the number of information units of in-car road messages and the dependent variables have taken into account the visual explorations, the memory recalling performances and indicators of the lane and the speed control. The results have shown that the number of visual explorations increase as a function of the number of units in each message, and that the mean time duration of each glance seems relatively stable (1.08 s. to 1.35 s.). The memory recalling performances are inversely proportional to the length of road information messages. The long road information messages (from 10 to 18 units) have an important impact on speed and trajectory control. Some psycho-ergonomics recommendations are proposed concerning the complexity of the in-car road information messages. (A)
Abstract