“…Former research has investigated the relationship between learners' cognitive load and their physiological behaviour. The physiological measures that have been used to investigate cognitive load are among others heart rate by electrocardiography (ECG), brain activity by electroencephalography (EEG), eye activity (e.g., blink rate, pupillary dilation), EDA, heat flux and ST (Antonenko, Paas, Grabner & van Gog, 2010;Haapalainen et al 2010;Scharinger, Soutschek, Schubert & Gerjets, 2015;Smets et al, 2018;Zagermann, Pfeil & Reiterer, 2016). Although a lot of physiological data, such as brain and eye activity, has been proven to be highly effective for measuring cognitive load, these types of physiological data often requires expensive sophisticated equipment that is highly obtrusive in measuring cognitive activities, especially in ecological valid contexts (Chen et al, 2016;Scharinger et al, 2015).…”