Blind tests specifically? Take, e.g., soda and diet soda, decant into identical containers with hidden labels, drink one, and log any effects before you check what it was. The brain is powerful. Some people experience real headaches because they think that WiFi or other RF gives them headaches. But they won’t get a headache from radio waves they don’t know about.

I don’t intend this in a mean way. If you do find out that it’s something else you could get relief from said migraines. Like the MSG folks who are probably just not drinking enough water when they go out to dinner, or are nervous about Asians or something. I once took placebo and a low dose of MDMA in a blind study and got them backwards. I was embarrassed for some reason but our brains really do construct much of what we perceive as raw sensory input.