Physiological indices directory

Directory content: This directory contains 21 .CSV files with electrodermal activity (EDA), electrocardiogram (ECG), blood volume pulse (BVP), and respiration data (recorded at 400 Hz) for each driver (i.e., ID_Number_BiosignalsData). All files were pre-processed in two steps to ensure the correct sampling rate: (i) removing lines with timestamps repetitions, and (ii) resampled to 400 Hz using regularly spaced and linear interpolation. This directory also includes a .CSV file reporting the data description (Legend_DataBiosignal).

Method and instruments: We used a BiosignalsPlux Research Kit (PLUX Wireless Biosignals, Lisbon, Portugal) to monitor participants’ ECG, BVP, EDA, and respiration data. The BiosignalsPlux system includes a wearable hub with an 8-channel configuration (analog ports) of 16-bit per channel resolution, using Bluetooth data transmission technology for synchronization with the driving simulator.

We used disposable, self-adhesive, pre-gelled Ag/AgCl electrodes (24 mm diameter) for the ECG and EDA measurements. The EDA was recorded employing a dedicated single-lead local differential bipolar DC sensor (0-3 Hz bandwidth, 0-100 µS range), with two leads (a positive and a negative lead, 5.0 ± 0.5 cm length each), each one ending with a dedicated electrode socket. Once we cleaned the skin with an alcohol-free disinfectant, we placed the electrodes on the thenar (negative electrode) and hypothenar (positive electrode) eminences of the left hand. We made sure to let enough space on the hand palm between the two electrodes to minimize the risk of signal artifacts due to the pressure of the hand on the steering wheel. The ECG was recorded with a single-lead local differential bipolar sensor (0.5-100 Hz bandwidth, ± 1.47 mV range), including a positive, a negative, and a reference cable, each one ending with a dedicated electrode socket. Once we cleaned the skin, we placed the electrodes on the participant’s chest (Lead II configuration): one electrode on the depression below each of the shoulder blades (reference on the left side, positive on the right side) and one electrode (negative) on the fifth intercostal space of the left side.

The BVP was measured through an optical, non-invasive ear-clip sensor (0.02-2.1 Hz bandwidth, 535±10 nm centroid wavelength), including a light emitter (LED) and detector. The sensor (LED and detector) was placed at the center of the left ear lobe.

The respiration data was recorded using an elastic, adjustable chest belt that included a piezoelectric sensor (0.059-1 Hz bandwidth, ± 1.50 V range). We placed the belt on the participant’s chest, over a cotton short-sleeve T-shirt, ∼2 cm below the pectoral muscles, and connected to the hub using a dedicated cable of about 110 cm total length.