Stage 2 – Execution in the Simulator Day at the Simulator

Table 12. Sequence of events at the simulator.

Once the initial data collection was completed and a DMP for each manoeuvre was provided, the participants were invited to spend a day at the Smartship Simulator to perform all four manoeuvres. The day before, an email (see Appendix 11) was sent in order to remind the participant of a few final details, especially concerning the use of caffeine and nicotine.

Interview – Part 2

As summarised in Table 12, the “simulator day” normally started with an introduction to the facility and an explanation of what would have been the daily schedule. Then the general interview (see Appendix 10) was completed, going through those questions that were specifically relevant to the simulator day. An example of one of those questions could be: “Caffeine Nicotine or other substances assumed recently (if any)”.

Equipment and Questionnaires

Before starting the manoeuvres, pilots were fitted with the equipment necessary to record the physiological variables. Once the electro cardiogram, electro encephalogram and eye tracker equipment were tested, pilots were required to perform a very simple mooring manoeuvre with a vessel different from those used in the experimental manoeuvres. This first manoeuvre was used as a test and a familiarization manoeuvre in order to double check recording devices and have the pilots acquainted with the bridge environment and the navigation equipment. After this familiarization manoeuvre, the

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remaining manoeuvres that were previously planned in Stage 1, were used in random order as “hot manoeuvres”, so all the data of interest could be recorded. The recording of physiological variables was achieved in the least obtrusive possible way, using wireless and portable devices.

ECG

For the recording of the Electrocardiogram signal, a Smartex® _{Wearable Wellness System}®

was used (www.smartex.it). This system, using two electrodes inbuilt in the fabric of the wearable t-shirt, was able to collect a full electrocardiogram. The system provided an input sensitivity of ±5 mV. The sampling rate was 250 samples per second, covering a bandwidth from 0.05 Hz to 30 Hz with a 12 bits resolution. Further analysis of the raw ECG signals, as better explained in section 3.5.3, was able to provide also the Heart Rate Variability (HRV).

Figure 11. Smartex ECG recorder - Wearable Wellness System (WWS)

EEG

The electro encephalograph signals were obtained using an Emotiv® _Epoc® _wireless

device (www.emotiv.com), featuring 14 channels: AF3, F7, F3, FC5, T7, P7, O1, O2, P8, T8, FC6, F4, F8, AF42. The sampling rate was 128 samples per second with a resolution of 14 bits (1 LSB = 0.51μV), covering a bandwidth from 0.2 Hz to 43 Hz, with digital notch filters at 50 Hz and 60 Hz.

Figure 12. Emotiv Epoc EEG recorder

Eye Tracking, Audio Recording and Pupil dilation

Eye tracking goggles ASL® _{Mobile Eye XG}® _{(www.asleyetracking.com) were used to record}

eye movements, audio and pupil dilation. The Eye Tracker goggles had a front HD camera that recorded what was in front of the subject at a rate of 30 frames per second. A second infrared camera was pointed towards the subject right eye and recorded the pupil movement and dilation (diameter measured in number of pixels). This system was then able merge the two channels, providing the gaze position through a red cross overlaid on the video recorded by the front camera. A calibration procedure, which determined where gaze was located within the scene, needed to be performed at the beginning of each recording. The audio was recorded by an inbuilt microphone.

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Figure 13. ASL Mobile Eye XG eye tracking goggles

The audio allowed to record pilots orders and “thinking aloud” reports in the form of intentions shared with the rest of the Bridge. Audio recordings provided also the measurement of experienced workload based on the ordinal ratings of the self assessment Likert scale described in the next section.

Self Assessment Likert Scale

Before the manoeuvres were started pilots were instructed about the use of a self assessment Likert scale which they had to refer to, to verbally report their level of “involvement or workload” during the manoeuvre. The scale, provided in Appendix 8 (and always kept in pilots’ sight), reported 7 different levels of “exercise difficulty”, meaning the personal level of workload experienced or effort necessary, in order to be able to manage the situation at the time of the question. The pilot, during the execution of the manoeuvre, was briefly reminded (every two minutes circa), with a quick question asked by the researcher (i.e. “How do you feel?”), to simply report a number according to the scale described below:

Level 7 was indicated as the level where the situation was felt so demanding, that was just about to be out of hand; level 6 was a challenging situation that required the complete attention of the pilot, working at almost 100% of his capabilities; level 5 was a situation requiring more attention than normal, but not felt as critical as level 6; level 4 wanted to depict a normal level of involvement where the pilot could feel perfectly capable to achieve the desired outcome with a necessary but comfortable level of effort

(routine operation); level 3 was an easy condition offering no specific challenge, with required effort below the average; level 2 was a very comfortable, almost effortless situation; level 1 indicated a situation of “complete boredom”, with very little or no involvement.

Self assessment scales present some disadvantages: they can tend to be situation specific and may fail to take into account the individual’s learning, experience, natural ability and changes in emotional state, they also might reveal little in terms of the brain mechanism involved in task performance (Baldwin, 2003). Nevertheless, self assessment scales are relatively easy to administer and interpret and they do not require extensive training or equipment (Luximon & Goonetilleke, 2001). In light of all those considerations, an additional Mental Workload measurement was adopted: the NASA TLX.

NASA TLX

The National Aeronautics and Space Administration-Task Load Index (NASA-TLX). NASA- TLX (Hart & Staveland, 1988) is a multidimensional scale for which the overall mental workload is a function of 6 subscales: 1. Mental Demand (MI), 2. Physical Demand (PD), 3. Temporal Demand (TD), 4. Own Performance (OP), 5. Effort (EF), 6. Frustration Level (FR). Refer to section 2.3.2 of this thesis for more details. At the end of each manoeuvre, after the post exercise baseline recording, the pilots completed a NASA TLX questionnaire in a Microsoft® Excel® electronic format.

Simulator

The simulator was principally used to gather data related to performance. The simulator was capable to record a conspicuous amount of technical measurements at a rate of 5 Hz. Some of those measurements were for example: Piloted Ships data such as latitude and longitude, lateral and longitudinal speeds, rate of turn and heading, propulsion settings etc.., environmental conditions such as wind intensity and direction, current, etc..

Experimental Manoeuvres

Before the beginning of each experimental manoeuvre, the Pilot was informed about which of the four planned manoeuvres was about to come next. The relevant Detailed Manoeuvring Plan (compiled in Stage 1) was reviewed with the researcher in order to evaluate any possible doubt or additional question. A video recording, where the pilot went through the plan with the researcher, was finally captured. Before the simulation was started an initial physiological baseline recording of at least 5 minutes was carried out. After the physiological baseline recording, the simulation was started, allowing the pilot to execute the manoeuvre. During the manoeuvre there were no interruptions or suggestions by the researcher who was generally acting as the ship’s Captain or, when required by the specific context, as the member of the bridge team more suitable to interact with the pilot at that time. Immediately on completion of the manoeuvre, once

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the simulation was stopped, another physiological baseline of at least 5 minutes was recorded.