Assuming that baseline works (i.e. results are very highly reproducible with little variance), the effects of interventions should be much easier to measure than they typically are in psych studies. Start with the basics: track room temperature and lighting, blood glucose and oxygenation, ventilation, background noise. As those change, measure the effects on performance on IQ test items. Run the test a few times on different days and in different places, and try to nail down the exact sources of all the variance seen day-to-day and place-to-place. Tracking down the causes of all that “everyday variance” is where most of the value would be.
Obviously, you could also test nootropics this way.
Obviously, you could also test nootropics this way.