I'd love to see a serious study of rapping, especially free styling and rappers who don't write their lyrics in advance (celebrity examples include Jay Z, Lil Wayne, Kanye). For everyone who hasn't tried to rap: it's nearly impossible to create or perform a good verse if you're not in the zone. Improvisational poetry to the beat is too demanding of your mental bandwidth if there's anything else going on in your head.

And I'd love to see this study done with both high and sober participants. Cannabis makes it significantly easier to enter flow state, and it's no coincidence that it's popular among rappers and other improvisational musicians.