Title: Age-related usability investigation of an activity tracker

Authors: Peter Rasche; Katharina Schäfer; Sabine Theis; Christina Bröhl; Matthias Wille; Alexander Mertens

Addresses: Department of Mechanical Engineering, Chair and Institute of Industrial Engineering and Ergonomics of RWTH, Aachen University, Bergdriesch 27, 52056 Aachen, Germany ' Department of Mechanical Engineering, Chair and Institute of Industrial Engineering and Ergonomics of RWTH, Aachen University, Bergdriesch 27, 52056 Aachen, Germany ' Department of Mechanical Engineering, Chair and Institute of Industrial Engineering and Ergonomics of RWTH, Aachen University, Bergdriesch 27, 52056 Aachen, Germany ' Department of Mechanical Engineering, Chair and Institute of Industrial Engineering and Ergonomics of RWTH, Aachen University, Bergdriesch 27, 52056 Aachen, Germany ' Department of Mechanical Engineering, Chair and Institute of Industrial Engineering and Ergonomics of RWTH, Aachen University, Bergdriesch 27, 52056 Aachen, Germany ' Department of Mechanical Engineering, Chair and Institute of Industrial Engineering and Ergonomics of RWTH, Aachen University, Bergdriesch 27, 52056 Aachen, Germany

Abstract: Activity trackers, measuring motion and steps, enable users to monitor their behaviour and may support a healthier lifestyle. To gain more detailed insight into initial and long-term use, a two-phase explorative study with two age groups (young/old) was conducted. The age of the younger group ranged from 19 to 30 years and of the older group from 60 to 78 years. In total, N = 30 participants (15 younger/15 older) took part in the first phase of the study. This phase lasted 4 weeks and provided in-depth information on usability as measured by the post-study system usability questionnaire (PSSUQ), on motivation, as measured by a seven-point Likert scale and on subjective mental effort during the initial contact, as measured by the rating scale of mental effort (RSME). N = 8 participants (4 younger/4 older) out of the original 30 decided to participate in a second phase, which lasted 6 months and was designed to observe long-term use of an activity tracker. The results show that the activity tracker's usability is generally suitable for both age groups. All participants were able to use the activity tracker independently without any special training or instructions from the principal investigator. Further, this study revealed that length of use of an activity tracker is independent of technology affinity and perceived usability. It decreases over time depending on the user's knowledge about his or her physical activity. Finally, indication for age-related differences in the requirements and key functions of an activity tracker were found.

Keywords: activity monitoring; age; behaviour change; health; older adults; persuasive technology; quantified self; wearable sensing.

DOI: 10.1504/IJHFE.2016.083506

International Journal of Human Factors and Ergonomics, 2016 Vol.4 No.3/4, pp.187 - 212

Received: 05 Jul 2016
Accepted: 01 Nov 2016
Published online: 08 Apr 2017 *

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