This was sloppy on my part. I meant &quot;interact&quot; in a statistical sense - <a href="https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Interaction_(statistics)" rel="nofollow">https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Interaction_(statistics)</a>.<p>I&#x27;m not a medical expert, so I&#x27;m a bit inconsistent in terminology, but have ran my fair share of (cognitive) psychological experiments (and developed methods for them), which rely on similar logic as to that of double-blind testing.