The purpose of this study was to examine interference between concurrently performed speaking and driving tasks. Participants included 60 adults, 30 males and 30 females, with no history of communication disorders. They were divided into three different age groups of 20 participants each: younger (20s), middle-aged (40s), and older (60s). The participants were given a list of topics to consider and were instructed to select eight topics that they could talk about; they completed five practice trials of the driving simulator prior to the experimental recording to eliminate practice effects. Each participant completed the speaking task and driving task both separately and concurrently. The speaking task consisted of producing a monologue about the topics that they had selected. Dependent measures for speech included metrics relating to intensity, fundamental frequency, and the ratio of speaking to pausing time. The simulated driving task involved maintaining a constant speed and lane position on a freeway. Dependent measures for driving included metrics relating to speed, lane position, steering wheel position, and a count of steering wheel turns. Results indicated significant divided attention effects in speaking time ratio, intensity, speed, and steering wheel control. There was a significant age effect for intensity and fundamental frequency as the younger group had less variation with these variables compared to the other age groups. There was a significant age effect for lane position, steering wheel position, and speed as the younger group had less variation in lane and position compared to the other groups and the older group had more variation in speed and steering wheel position compared to the other groups. There was a significant gender effect for intensity and lane position as the females had less variation in intensity and more variation in lane position compared to the males. These findings suggest that divided attention conditions impact both speech and driving performance. The results also shed some light on the effects of age on concurrently performed speech and driving tasks. These findings imply that divided attention conditions should be incorporated in treatment to help patients generalize the skills learned in therapy to everyday communication.



College and Department

David O. McKay School of Education; Communication Disorders



Date Submitted


Document Type





bidirectional interference, age, divided attention, acoustic speech measures, driving