Fig 4: distribution of failures
Fig 5: correlation space station/simulator
In the space station test 13 participants (41%) were so occupied with their problem solving that they at least once forgot their permanent task.
In the BRISIM I test, because of the distractions, 13 participants (41%) sailed at least once outside the channel.
This experiment shows that cognitive lock-up is a consistent personality factor
In the second experiment (BRISIM II), again 32 experienced watchofficers were tested on their ability to keep overview in a more general context.
The above mentioned space station test was compared now with a more general sailing mission. The simulator part consisted of a 3-track route along the Belgian-French coast, to be sailed by the participants by night (simulated starting time: 2.00 AM). Apart from the RADAR and BCDIS, all navigation equipment was available. Because of that RADAR and ECDIS absence, the participants had to use all their "visual" experience. All in real life existing navigational aids like lighthouses and buoys were present. The participants were on the bridge alone, but the auto-steering-mode was available. The route is known to be quite difficult to sail because of the sandbanks and currents. Halfway the second track, a shoal must be passed within a bracket of the 2 hours before of after HW; therefore a minimum speed of 13 knots was required. There was other traffic in the area, not on collision course, but close enough for distraction of the attention.
Fig 6: sailing area Belgian coast
Two times on each track, a questionnaire was administrated. Each questionnaire consisted of 10 questions about actions, about information of the own ship and about the environment. The time available for each questionnaire was 1 minute. The first questionnaire on each track was presented just after the turn (the new orientation or NO-moments)
After approximately ten minutes on the new track (familiar orientation or FO-moments), the second questionnaire was administrated. In sum, 6*10 questions were presented to each participant (questionnaire N01 to F03).
After the test was completed, all questions were scored according to a fixed protocol page:
Score 0 was given when the question had not been answered, the answer was either too far away from the right answer or totally wrong.
The other answers got a score 1.
Each questionnaire was weighted with the percentage of answers in that particular questionnaire that had got a score higher than 0. This was done in order to reward a large amount of (global) knowledge more than a small amount of (detailed) knowledge. All questions were the same for all participants but different in topic.
The answers were classified into three different categories:
・topic of the question (e.g. heading, character of buoys, speed etc.)
・Time to which the question referred (recent past, present, near future)
・Vicinity to the participant and the own ship
No difference was found between topics related to past or the present. However, knowledge about topics concerning the near future appeared to be poorer than knowledge of topics in relation to the present or the past.
Furthermore it was confirmed that knowledge of facts in close relation to the participants were better represented than knowledge of topics in the environment of the ship.
No evidence was found for the supposition that the ability to keep overview in a well defined taskparadigm of permanent and incidental tasks would have a relationship with a more general sense of keeping overview
By these experiments evidence was found for:
・The supposition that the ability to keep overview is quite consistent over individuals but only under certain circumstances
・Situational awareness under watch-officers is quite low (2,95 on a 10 scale)
・During a turn the overview (situational awareness) is decreasing
The third experiment
In the third experiment (BRISIM III) the emphasis by using the bridge-simulator was laid on the influence of different task-factors:
Elements that are often encountered during work on the ship's bridge are analyzed according to their ability to distract the attention of watch-officers from other tasks and increasing the probability that the overview will be lost. Furthermore, the effects of fatigue and sleep deprivation to keep overview were investigated.
4 different test-conditions were compiled:
Condition A: a scenario without incidents and only wind noise (control subtest).
Condition B: a scenario with verbal distraction by 2-incident and wind/VHF noise (traffic subtest).
Condition C: a scenario with 3 incident traffic distraction combined with wind noise (verbal/ambiguous subtest).
Condition D : a scenario with a 6 incidents traffic and verbal distraction, combined with wind and VHF noise (combines subtest).
For the geographic area the river Schelde near Terneuzen was chosen. During the run a strong current was running, drifting the ship strongly to the shore and the wave height was 3 m. (significant). With an initial speed of 16 knots the duration of the run was about 20 minutes.
Fig. 7: River Schelde