Testin, F. J., & Dewar, R. E. (1981). Divided attention in a reaction time index of traffic sign perception. Ergonomics, 24(2), 111-124.

Laboratory studies of traffic sign perception have often neglected to duplicate the divided attention demands of the driving task, even though it has been suggested that the inclusion of a loading task would increase the validity of such research. The present experiment examined the need for this division of attention by requiring subjects to identify traffic sign messages while performing a second loading task involving the cognitive components of detection, identification or memory. A control group received no loading task. The reaction times to 16 signs were correlated with the legibility distances of the same signs measured in a previous roadway experiment. Contrary to the conclusion of Dewar et al. (1976) that a loading task may increase the validity of the reaction time index, the present study found no advantage to using a loading task in association with the reaction time measure of traffic sign perception.