How is multi-tasking different from increased difficulty?

Zachary L. Howard, Nathan J. Evans, Reilly J. Innes, Scott D. Brown, Ami Eidels

Research output: Contribution to journalReview articlepeer-review

22 Citations (Scopus)


With the advancement of technologies like in-car navigation and smartphones, concerns around how cognitive functioning is influenced by “workload” are increasingly prevalent. Research shows that spreading effort across multiple tasks can impair cognitive abilities through an overuse of resources, and that similar overload effects arise in difficult single-task paradigms. We developed a novel lab-based extension of the Detection Response Task, which measures workload, and paired it with a Multiple Object Tracking Task to manipulate cognitive load. Load was manipulated either by changing within-task difficulty or by the addition of an extra task. Using quantitative cognitive modelling we showed that these manipulations cause similar cognitive impairments through diminished processing rates, but that the introduction of a second task tends to invoke more cautious response strategies that do not occur when only difficulty changes. We conclude that more prudence should be exercised when directly comparing multi-tasking and difficulty-based workload impairments, particularly when relying on measures of central tendency.

Original languageEnglish
Pages (from-to)937-951
Number of pages15
JournalPsychonomic Bulletin and Review
Issue number5
Publication statusPublished - 1 Oct 2020
Externally publishedYes


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