## 2 Materials and Methods
### Equipment and Materials  
The workstation was designed and developed within the present study to consider the highest possible number of implicit and explicit user data. It was composed of a perforated blackboard (Figure 2a,b), an eye-tracking pair of glasses (Pupil Labs, Figure 2d), and an amplifier for the monitoring of psychophysiological signals (ProCompt system, Figure 2c). The handmade blackboard consisted of a hollow parallelepiped with a square base (\(60\times 60\times 50\) cm) and four telescopic supports, to allow the adjustment of its relative height. Two of the four vertical sides had 50 holes arranged in 5 parallel horizontal rows, with threaded inserts in each hole, able to hold hexagonal-head steel bolts (\(8\times 25\) mm). The entire system could register every voluntary human-workstation interaction (duration and frequency), from when the participant collected a bolt to when s/he completely tightened it on the blackboard. Indeed, a Makey Makey board (Makey Makey LLC (c); JoyLabz, Santa Cruz, CA, USA), installed inside the blackboard and connected to a laptop, allowed this information to be sent to a portable computer. These data were recorded using E-Prime software (v.2.0; Psychology Software Tools (c); Pittsburgh, PA, USA). The participants, the board, and a metal drawer containing the screws were part of an electrical circuit. A bracelet worn by participants was an important part of the system. When s/he touched one of the circuit components, the ensuing electrical contact sent a trigger to the connected computer to record the information of the interaction which had just occurred. Two GoPro Hero 4 cameras, one mounted in front of the participant (i.e., over the blackboard; see Figure 2b) and the other on a lateral position, allowed the continuous monitoring of the participants. The GoPro and the eye-tracker world-camera sampling frequency was set to 30 frames per second to permit an offline synchronization of the video-recordings. A cinematographic clapper was utilized for synchronizing the measures collected from the human-workstation interactions and the implicit measures. This tool was also interfaced, through the Makey Makey board, to the E-Prime software. This clapper created a detectable electrical contact, which was then synchronized with the frame corresponding to the closure. Therefore, the closing of this instrument was carried out in the cameras' visual field to synchronize the video streams and other devices. Finally, the workstation was equipped with a lighting system, consisting of six strips of SMD 5050 LEDs, emitting a total of 1100 lum  
Figure 2: Components of the ad hoc workstation. (**a**) Blackboard distant view; (**b**) blackboard front view; (**c**) ProComp5 Infinit; (**d**) Pupil Labs glasses. adjustable support, anchored to the upper base of the blackboard, to maintain the same level of lighting in the laboratory. We utilized a pair of binocular eye-tracking glasses (i.e., Pupil Labs; Pupil Labs GmbH (c), Berlin, DE; Figure 2d) in the experiment. This tool is capable of gathering data on fixations, blinks, saccades (duration and frequency), and pupil diameter. It was connected to an MSI laptop (Intel Core i7-6700 HQ, screen resolution \(1920\times 1080\)). The software Pupil Capture (Pupil Labs GmbH (c), Berlin, DE) allowed the system calibration and the data recording (sampling frequency: 120 Hz). The software Pupil Player (Pupil Labs GmbH (c), Berlin, DE) was utilized to export the eye-tracking data. Lastly, a Procomp5 Infiniti amplifier (Thought Technology Ltd.; Montreal, QC; Figure 2c) and its software (i.e., BioGraph Infiniti) permitted the recording of psychophysiological data. The software ran on a second MSI laptop (in the same configuration as the aforementioned laptop). The heart rate (HR) was acquired using a blood volume pulsimeter positioned on the left middle finger. The electrodermal activity (EDA) was collected using two electrodes placed on the annular and index fingers of the same hand.