Background: Human walking is a highly automated motor task, however if the individual's attention is divided, gait can be negatively affected. Although the effect of divided attention has been usually tested with standardised cognitive tasks, the common task of walking while talking on the phone may represent an ecological dual task scenario.
Research question: What is the effect of divided attention on locomotion when using a mobile phone?
Methods: Thirty-seven healthy participants were asked to walk while performing different cognitive tasks: counting and spelling backwards, talking on the phone (handset by the ear and hands-free), and texting. As a control, extra postural conditions were tested: holding the phone by the ear (without talking) and carrying the phone as in the texting task. These tasks were compared with normal walking (no other cognitive or postural task). Twenty participants also performed the same tasks with the addition of an obstacle halfway through the walkway. Gait performance was measured using non-invasive inertial sensors. Step time and mediolateral acceleration range were calculated.
Results: Step time increased when counting (mean ± standard error 0.63 ± 0.02 s, p < 0.001), spelling backwards (0.67 ± 0.03 s, p < 0.001) and texting (0.61 ± 0.02 s, p = 0.005) compared to normal walking (0.56 ± 0.02 s). Compared to normal walking (8.03 ± 0.58 m/s2), mediolateral acceleration decreased when counting (6.43 ± 0.39 m/s2, p < 0.001), spelling backwards (6.67 ± 0.44 m/s2, p < 0.001), when talking on the phone while holding the phone (7.28 ± 0.48 m/s2, p = 0.003), or hands-free (7.28 ± 0.40 m/s2, p = 0.004), or texting (6.71 ± 0.50 m/s2, p < 0.001). Introducing an obstacle confirmed these results.
Significance: This study shows that even in young and healthy individuals, gait is affected by divided attention. Furthermore, the results show that common and ecological cognitive tasks, such as phone use, could induce measurable worsening of gait performance. Individuals should be careful when walking and performing other tasks that could distract them, by dividing their attention.
Keywords: Divided attention; Gait control; Mobile phone.
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