A recent study by Dr Gabriel Tillman (former RHD student in the School of Psychology, University of Newcastle; currently at Vanderbilt) and colleagues examined cognitive workload in drivers and passengers.
The study appeared in the journal Attention, Perception and Psychophysics, and gained traction via the Psychonomic Society's blog, in an article by Cassandra Jacobs. In a nut shell, researchers Gabriel Tillman, David Strayer, Ami Eidels, and Andrew Heathcote conducted a study looking at the impact of high cognitive load across three conditions: driving without distractions, driving and holding a conversation with a hands-free mobile phone, and driving and holding a conversation with a passenger. During the driving session, participants were presented with a peripheral red light and had to respond to it as quickly as possible by pressing a micro switch (the Detection Response Task, DRT).
The researchers analysed the time to detect the light and found participants were substantially slower to respond to the light when they were engaged in conversation with another person, in both the hands-free mobile-phone case as well as when talking to a passenger. In addition, and in the tradition of the Newcastle Cognition Lab, the researchers fit the data to a computational model of choice and response time. The full results are detailed in the AP&P article, here.
A nice summary is available in the blog-article by Cassandra Jacobs here.
Dr. Gabriel Tillman