A study to measure spare capacity of driver's attention payable to cognitive subtask

An attempt was made in a laboratory experiment to measure the spare capacity of attention payable to a cognitive subtask while driving. A video movie taken from the front panel of a car running through roads in residential areas and woods was projected onto three screens in front of a subject subtending a wide visual angle. The main task of the subject was to control the steering wheel and trend the acceleration and braking pedals in accordance with the movie. Simple addition tasks of two difficulty levels were lorded to the subject as a cognitive subtask. The stimulus movies were classified into seven different types of road situation such as straight lines in a wide road. The results showed that the spare capacity of attention while driving changed with road situations similar to those obtained in previous studies based on field trials. This indicated the validity of the laboratory experiment to some extent in studying driver's cognitive and behavioral characteristics.