Impacts of physical and mental workload interaction on human attentional resources performance

Motivation -- Task workload is key determinant of human performance. It may include physical and/or cognitive components, and these can interact to influence operator performance. This research study investigates the interaction of physical workload, mental workload and arousal level on attentional resources in order to predict performance. Research approach -- This study was divided into two experiments. In both experiments, fifteen participants (aged 25--35) performed a physical task (pedalling on a bicycle-ergometer) concurrently with a mental task under nine levels of workload in a 3x3 design (low, medium and high levels for both physical and mental). In the first experiment, the mental task was designed to occupy verbal attentional resources through mental arithmetic, whereas a spatial figures task was used in the second experiment to evaluate spatial resources. Findings/Design -- The hypothesis of the study is that optimum performance occurs at intermediate levels of workload, whereas poor performance is observed at the extreme low and high levels of physical and mental demand due to underload and overload. It is also anticipated that physical and mental workload can interact to 'offset' underload or overload decrements. Originality/Value -- The present study will fill the gap in the ergonomics literature by explaining performance degradation due to mental underload and by clarifying the interaction with physical workload. Take away message -- It is possible that moderate levels of physical workload could compensate for attentional resource reduction with mental underload.