Looking or Listening?

Abstract

We conducted an experiment with 22 participants to investigate the effect of presentation style of a secondary task on a 1-D tracking task that simulated gap control in driving. Participants operated the tracking task with a foot pedal while performing a secondary task (counting vowels in a list of multiple letters) under conditions involving different modalities (audio/ visual), presentation styles (simultaneous/ sequential), task complexity (the number of distractors), and time dependency (list length). Our results showed that audio conditions with a longer and/or more complex secondary task did not improve primary (tracking) task performance, even though eye gaze dwelling time on the primary monitor in these cases tended to be substantially longer than the corresponding times in visual conditions. For a more complex version of the secondary task (longer list lengths) visual presentation of the task all at once (simultaneously) led to better performance then sequential presentation (whether visual or auditory). When given a choice people also tended to prefer simultaneous visual presentation of the secondary task. We discuss the effect of presentation modality of the secondary task in terms of its implications for user interface design in vehicles.