Do you have links to any of these studies? I'm curious since it does not align with my personal experience, I find myself most productive on my single 720p screen -- perhaps I am missing something?
It varies from task to task, and operating system support is a confound, but basically it comes down to how often you have to scroll or switch windows to do whatever you are working on. For example, a print designer might do best with a single monitor large enough to hold the full document they’re working on at comfortable resolution while a programmer might be limited by having their editor and something like a debugger, browser, simulator, etc. simultaneously usable so two monitors might be better than one big one until it’s so big that those all fit.
