U.S. flag

An official website of the United States government, Department of Justice.

Estimating cognitive load using pupil diameter during a spoken dialogue task

NCJ Number
Date Published
4 pages

The authors explore the feasibility of using pupil diameter to estimate how the cognitive load of the driver changes during a spoken dialogue task with a remote conversant.


The conversants play a series of Taboo games, which do not follow a structured turn-taking nor initiative protocol. The authors contrast the driver's pupil diameter when the remote conversant begins speaking with the diameter right before the driver responds. Although the authors found a significant difference in pupil diameter for the first pair in each game, subsequent pairs showed little difference. The authors speculate that this is due to the less structured nature of the task, where there are no set time boundaries on when the conversants work on the task. This suggests that spoken dialogue systems for in-car use might better manage the driver's cognitive load by using a more structured interaction, such as system-initiative. (Publisher abstract provided)

Date Published: January 1, 2013