Natural Break Points: The Influence of Priorities and Cognitive and Motor Cues on Dual-Task Interleaving

CP Janssen, Duncan Brumby, R Garnett
in Journal of Cognitive Engineering and Decision Making, Journal article


What factors determine when people interleave tasks when multitasking? Here the authors look at the role of priorities and cognitive and motor cues. A study was conducted in which participants steered a simulated vehicle while also dialing two phone numbers that contained sets of repeating digits. Participants tended to interleave tasks after typing in a complete set of repeating digits and sometimes also at the cognitive chunk boundary. The exact pattern of how participants interleaved these tasks depended on their priority objective. A modeling analysis that explored performance for a series of alternative strategies for task interleaving, given the cognitive and task constraints, suggested why participants avoided interleaving at other points: Such strategies tend to move performance away from a trade-off curve that strikes an optimal balance between dialing and driving performance. The study highlights the role that cognitive and motor cues can play in dual-task performance and the importance of being aware, and acting on, priorities. Further implications and limitations are discussed. © 2012 Human Factors and Ergonomics Society.