Hello,
Thank you for your interest and your questions ! I'm not sure I fully understand them, but I will try to answer it my best.
1. We analyzed interactions effects between the position of the question of fatigue (before or after the experimental block) as well as the position of the block, both in relation to the type of break.
We didn't find a significant effect for question's position X type of break but we find an interaction effect between the block's position X the type of break. We found a bigger difference between the first and second experimental block. Precisely, participants in the relaxing and cognitive condition felt less fatigue in block 1 than in block 2, whereas it was the contrary for the participants in the physical condition.
This raises the question of whether the question about fatigue was too general, and should have focused more on mental fatigue, unless the participants in the physical condition felt more exhausted after exercises that were not physically demanding.
2. Participants as you said were novices, most of whom have never taken part in a weapons detection task. As a result, a novelty effect probably made them more engaged to the task in the beginning of the experiment, as seen with their relatively low level of fatigue. Then, with the time spent on the task, this effect must have faded as the fatigue became significantly greater.
Your point about it is very interesting ! It is possible that the learning effect may have had an effect on fatigue, but that's something we didn't investigate. Thank you for the feedback.
3. With professional screeners, we would have used a measure of work engagement instead of task engagement and perhaps we would have a more precise and concret understanding. It can be assumed that the screener's engagement to their work would be higher than that of novices, with confirmed expertise and therefore invenitably better performance. If fatigue is an element that can be "tamed" in the literature, if it is the cas it can also be assumed that screeners will fell less of it.
I hope I've been able to answer your questions !
Have a nice day.