# Assessing Drivers' Physiological Responses Using Consumer Grade Devices
### Devices Used to Measure Driver's Physiological Responses  
There is a great variety of available devices for capturing physiological signals. Most often higher reliability increases the price of the device, and thus reduces the availability. Devices used for signal capturing vary from study to study. Some even make their own custom capturing devices. Among the presented studies, Biopac MP-150 was often used as an overall acquisition system [7; 20; 27], also FlexComp Infinity system [8; 34], Nexus-10 from Mind Media Schepersweg [11], Medac Systems/3 [25], and Geodesic EEG System 300 [35] were mentioned. EEG was measured with NicoletOne Ambulatory EEG [6], EMG was measured with Bagnoli-87m [23], eye movement with FaceLAB(r)[25]. Bititium's Faros was also used in many studies [36; 37; 38]. Based on the available research it can be concluded that physiological signals can give important information about the human's state and prediction of human behavior or medical state. It is also noticeable that with the introduction of wearable devices, the research studies using such signals are no longer limited to medical and laboratory environments, but can be used also in dynamic environments such as vehicles. This can however bring \"noise\" (e.g., motion artefacts, quantization noise, electro-magnetic interferences from other devices, etc.) to the measured signals and therefore, it is important to be aware of this limitation when choosing a measuring device and later when performing the analysis. Therefore, we assessed suitability, accuracy, and robustness of two commonly used commercially available devices in a simulated driving environment. The E4 wristband can measure BVP, inter-beat interval (IBI), heart rate (HR), electrodermal activity (EDA) or GSR, skin temperature (ST), and motion with an accelerometer. A detailed presentation of the device can be found in the next section. In many studies, the raw data from the E4 device was used for assessing stress levels [39; 40; 41; 42; 43; 44]. [PERSON] et al. used all of the available E4 output signals (GSR, ST, HR, BVP, and motion) to detect various types of acute stress such as social, completion, emotional and mental stress, and showed that using their algorithm, they can detect stress with 87% accuracy [39]. [PERSON] et al. on the other hand tried to estimate the relationship between EDA signals and increased cognitive workload using the E4 [45]. Their results showed that there is a somewhat linear relationship between these data. Furthermore, it has also been used in studies of affective computing in general [40; 46], in medical researches for heart arrhythmia and atrial fibrillation detection [47; 48; 49]. Studies report also on using E4 data for assessing overall functional health of people with dementia [50] and creating of personal assistants for forgetful people [51]. [PERSON] et al. even tried to use the HR data for seizure detection; however, their results showed that detection performance was considerably lower to the usually used hospital and wearable Faros device [52]. Additionally, there seems to be a growing trend of using E4 data in biofeedback applications [53; 54; 55]. When compared to other laboratory (stationary and wearable) devices, E4 showed comparable results. [PERSON] et al. compared the E4 device with stationary sensors for ECG and GSR [41]. Their results showed incomplete IBI data, however mean values of HR and standard deviation of HR showed good stress discrimination power. For the GSR, their results showed that due to the placement, data from the E4 yielded higher stress discrimination power than the signal measured with the stationary sensors placed at the fingers. When compared for emotion recognition to higher grade laboratory equipment--Biopac MP150, it was found that E4 can provide comparable results [40; 56]. However, based on currently available data, no research was found on E4 being used in a driving environment. Faros is a family of ECG devices by Bititium. Faros 360 is able to measure 3-channel ECG, body temperature, and accelerations.