Buddhist scholars insist that while we can have multiple threads of attention in our awareness, like strings with pearls of experience/thoughts we can only actually hold one little pearl of information from that stream in our attention at a time, and that we flit between them quite rapidly.
Personally, I sort of agree, but I notice that there seems to be a time-compression thing happening where the pearl delivered to attention can contain a compressed summary of continuous perception. This seems to work for 2 things at once in awareness. When you start monitoring 3+ streams, there are gaps. And even maintaining the 2 streams continuously is exhausting so the mind tends to relax a little and leave gaps on a normal basis, but it seems like it can monitor dual feeds when its particularly important.
My understanding is that neuroscience largely seems to agree with the above.
(Actually, I'll note that the USUAL mode of being doesn't even monitor one stream continuously. A lot of the weird effects (and deeply interesting ones!) they talk about in meditative arts seem to pop up when you progress to being able to hold truly continuous attention.)