Journal of Agricultural Safety and Health 26(1): 5-14 © 2020 ASABE ISSN 1074-7583 https://doi.org/10.13031/jash.13223 5 Easily Applicable Methods for Measuring the Mental Load on Tractor Operators H. Arvidsson, G. Larsson, A. Larsolle, G. Neely, P.-A. Hansson ABSTRACT. Agriculture technology is moving toward automation, placing operators in a supervisory role. This change in operator workload may lead to increased stress and higher mental load, resulting in reduced attention and hence greater risk of illness or injury to humans and damage to equipment. This study investigated the use of easily ap- plicable equipment to measure mental load. Three methods were used to measure the mental load on machine operators: heart rate monitoring, two types of electroencephalo- graph (EEG) evaluation, and an assessment protocol. Three driving exercises (general driving, slalom driving, and loading) and a counting exercise were used in a driving sim- ulator to create different levels of mental load. Due to the number of exercises, a single- scale assessment protocol was used to save time. We found that only the assessment pro- tocol gave clear results and would work well as an evaluation tool. The heart rate and EEG measurements did not provide clear data for mental load assessment. Keywords. Agriculture, Awareness, Continuous measurement, EEG, Heart rate, Mental load, Simulator, Single-scale assessment, Tractor operator, Work machinery. griculture technology is moving toward equipment that automatically handles machine settings and positioning. For example, GPS technology automatically positions and drives tractors so that they function in the most efficient way possi- ble, relegating the operator to a predominantly supervisory role. These advances should decrease the physical workload because the operator can work more comfortably. For example, Karimi et al. (2012) found that tractor operators spent less time looking straight ahead, backward, and to the sides and more time monitoring the equipment’s display terminal when using a GPS-assisted autopilot, although they spent more time on each observation. This means that time previously spent positioning the equipment is freed up for supervision at a more relaxed pace, resulting in a less stressful work environment. However, reducing the variety of work may result in increased levels of stress or re- Submitted for peer review in November 2018 as manuscript number JASH 13223; approved for publication as a Research Article by the Ergonomics, Safety, & Health Community of ASABE in September 2019. The authors are Hans Arvidsson, Senior Testing Engineer, RISE Research Institutes of Sweden AB, Umeå, Sweden, and Department of Energy and Technology, Swedish University of Agricultural Sciences, Uppsala, Sweden; Gunnar Larsson, Researcher in Agricultural Engineering, and Anders Larsolle, Lecturer in Agricultural Engineering, Department of Energy and Technology, Swedish University of Agricultural Sciences, Uppsala, Sweden; Gregory Neely, Professor, Department of Psychology, Umeå University, Umeå, Sweden; Per-Anders Hansson, Professor, Department of Energy and Technology, Swedish University of Agricultural Sciences, Uppsala, Sweden. Corresponding author: Hans Arvidsson, RISE SMP Svensk Maskinprovning - Testing, Box 4053, Umeå 904 03, Sweden; phone: +46 (0)70 278 76 76; e-mail: hans.arvidsson@smp.ri.se. A