Objective measurement methods to quantify the health status of individuals date back a long time. As one such example, electroencephalography (EEG) has been used for over a century to analyze electric currents in and around the brain and is used widely in clinical healthcare systems. Unfortunately, gold-standard clinical EEG systems usually require a lot of time to set up, are limited in mobility, and are not designed to look inconspicuous. However, as EEG directly measures electrical correlates of the brain with a high temporal resolution, it is an important measurement method and of high interest for mental state classification. Therefore, wearable EEG devices are being developed for various use cases.
One area of application of wearable EEG devices that holds great promise is the classification of mental workload and stress. “Mental workload may be viewed as the difference between the capacities of the information processing system that are required for task performance to satisfy performance expectations and the capacity available at any given time.” (from: 'Workload: An examination of the concept', by Gopher and Donchin). Additionally, it has been shown that high levels of mental workload over long periods of time can lead to an increased risk of coronary heart disease and hypertension, amongst others. Mental workload and stress are closely related topics, and a high mental workload is regarded as a preliminary factor for stress. When mental workload increases, stress levels rise and mental fatigue can be developed, which might result in deteriorating mental health. While not every mental workload directly results in work-related stress, the long-term consequences of high levels of mental workload and stress might be very costly, which is why accurate time-series classification (TSC) is so important.
We want to move this technology directly where it is needed: outside of residing only in clinical or laboratory environments, bringing it right into your hands, ready to use and to assist you in living a longer and healthier life! For this purpose, we conducted a systematic literature review on mental state classification using wearable EEG. Alongside many findings on data pre-processing, the applicability of artificial intelligence and more, one of our findings was that multi-modal TSC applications outperform their best unimodal counterparts. Consequently, in our ongoing studies, we are combining the utilization of wearable EEG with other wearable devices capable of measuring additional physiological signals, such as the heart rate. Alongside the desire to bring the technology closer to individuals, as of Jan. 2024, we are working towards including low-cost wearables in our studies (e.g. the EmotiBit sensor suite).