piece of mind

I like listening to music or listening to videos or podcasts while I'm doing other things. You would think that if I'm doing something purely visual - like scrolling and pinning on pinterest, or doing art - that I could listen to and pay attention to a podcast or a video where someone is talking about something or having a discussion, but I can't. I can do it, but, if I get really engrossed in what I'm looking at on pinterest or the art that I'm doing, the discussion becomes like background noise and I'm only fully conscious of a word or two here and there. 

I only realised that this was the case when I was trying to scroll through pinterest and listen to an interview at the same time. I noticed that my thoughts about the images I'm looking at, crowd out my engagement with the interview. I was surprised, because I had the idea that looking at images would use a different part of my brain, so that process could go on at the same time as the process involved in listening to a discussion, but it seems like similar mental mechanisms are involved. 

I can only really give my attention to one thing at a time. I can be doing more than 1 thing - like say, I'm writing, researching, listening to music and planning something - but at any given moment, my attention will be on one of those things, and the others will be in the background. 

It makes me wonder what actually is attention and how does it work? Is the problem that the same mechanisms are operating when I listen to a discussion as when I look at art, so one will always crowd the other out, or is it that the two different mechanisms operate in different parts of my mind, but my attention can only be on one of those mechanisms at a time? I feel like the first option is more accurate but both options are too much of a simplification. They're both based on the idea that different processes in the brain happen in some kind of different space, and the brain is a lot more complex than that. When I look at and think about images on pinterest, it probably activates neural pathways all over my brain. The mind is not divided into compartments.