Not based on scientific data, just my own experience
When I was a teen, way back in the stone age, we didn't have Google to look up song lyrics. We had to listen to a song over and over and over...and over to learn the lyrics. And, knowing the lyrics was extremely important so we could show off our knowledge of the lyrics to our friends! Because, for some reason, knowing all the lyrics to a song meant you were a genius!! Believe me, I impressed a lot of people with my knowledge of lyrics in my teen years!
Today, I was thinking about how I can hear a song from 50 years ago, and not having heard it for over 20 years could remember each and every lyric. Word for word. And yet, other songs I could only remember the chorus to. That got me to thinking (heading into dangerous territory there, lol). Why is it that some of the "oldie" songs I can only remember the chorus to and yet others the entire and complete word for word lyrics?
That's when I remembered how I used to sit in my bedroom listening to a song, actually dissecting it's lyrics, over and over. Until the lyrics were ingrained into my brain. Yet, the songs I only remembered the chorus to I hadn't done this with. And why now when I listen to songs I mostly only remember the chorus and not the entire lyrics. Especially since the "age of the internet" was born. Today, if I want to know the lyrics to a song, I just Google it. Mostly just one time. Just to get an understanding of the words and what the vocalist is actually saying.
Now, when I hear newer songs on the radio, ipod, cell phone, or whatever electronic means I choose to listen with, I mostly only remember the chorus of the song. That's probably because the chorus is what stands out the most in a song (because it's repetitive) and is what I focus on while completing other tasks. Therefore, that is the portion of the song that becomes embedded within my brain. Whereas when I was a teen I was focusing, without distraction, on the entire song.
You may be asking yourself, "what does this have to do with prepping?". Well, let me tell you. (You really didn't think I was just going to leave you hanging, did you?)