Mental stress/workload is now considered as an important element that affects design creativity. Many physiological measures such as Galvanic Skin Response (GSR), Electrocardiogram (ECG), Electromyogram (EMG), Blood Pressure (BP), Skin Temperature (ST), Blood Volume Pulse (BVP), respiration rate (RIP) and Electroencephalogram (EEG) are used to identify mental stress level (Karthikeyan, Murugappan, & Yaacob, 2011; Lee, Jo, & Lee, 2011; Michon, 1966; Roscoe, 1992; Ryu & Myung, 2005; Wilson, 2002).
This thesis aims to explore the relation between mental stress/workload and physiological measures and using those measures to identify the correlation between mental stress and design activities. One measure is Heart Rate Variability (HRV). The LF/HF ratio derived from HRV was used as an indicator of mental stress. The average value of LF/HF of different activities during a design experiment was computed and then clustered into seven levels which represent different levels of mental stress. The result showed that, during a cognitive design experiment, most of the activities in a design process were performed under low levels of mental stress and there was no correlation between types of design activities and levels of mental stress. Another measure is Galvanic Skin Response (GSR). Mean GSR of several design activities under different stress levels during a design experiment was calculated to investigate if it can be used as a reliable measure of mental workload. The result showed that mean GSR is significantly lower in baseline compared to working state and GSR in the pre-test resting state is significantly lower than GSR in the post-test resting state.