The more I think about it, the more problems I see with this study.
Starting out, you are not providing a statement of methodology, as I already indicated. I understand that "not into Maiden (or metal for that matter)" is meant to be a quantification of your test subject's potential prejudice towards the experiment, but the problem is that the quantification is worthless if we are not provided with any data to follow your assessment. Does your test subject merely shrug and say "meh" when they hear The Trooper or do they want to rip their ears out and fill them with manure when exposed to Megadeth?
I find this problematic because you are depriving your audience of the possibility to reproduce your experiment and compare the results. Granted, I have no access to your test subject, but I am also not able to find one with the same values myself. Granted, finding a person "who's not into Maiden (or metal for that matter)" is not difficult, but what other conditions may speak about the possible prejudice of the subject towards the experiment? What environmental conditions did the experiment take place in? To name but one of many possibilities, the (relatively) positive response of your subject may be due to their suffering of a fever which was cured by the cowbell in the song. Did you conduct medical tests before and after this incident?
To be fair, I am not criticising your study per se, nor do I question its validity, but I find this publication disappointing. It makes your experiment look like a totally ridiculous mini-study.