Is the "improvement" real or imnagined?

This thread may be of interest to no one, but I was inspired by @inna post to start a thread. I had a recent experience that may touch on broader unresolved (unresolvable?) questions. I'm mostly happy with my system and my room has been professionally treated. I don't have an ideal listening chair-the back comes up to ear level, maybe a little above. Concessions have to be made to old and crumbling neck vertebra that need support.

I know that high back seating can in theory affect the sound through reflections. So, I got the bright idea to try to mitigate that-I'm sure its not original.

I bought a weighted blanket-quite thick and covered the chair. I put an Afghan blanket over that, the last one my mom crocheted, so its magical already. I perceive improved detail and better imaging -certainly not huge, but a subtle improvement that I hear, or at least think I hear.

So, maybe there is some science behind this, makes sense the blanket would reduce reflections. On the other hand, maybe its simply expectation bias, placebo effect, whatever, at work because there is science behind that as well, and its hard to imagine this is a big thing.

So, how do I know if its real or imagined? Its not a big deal, no real investment and only a very subtle perceived change, but it does relate to other issues that are often debated, sometimes heatedly, on this forum. How do you account for, or eliminate expectation bias, other than a proper double blind test which I'm guessing most of us are not going to do when auditioning equipment? 

I found this interesting, maybe no one else does. Thoughts?