Comment by dspillett

https://en.wikipedia.org/wiki/Nocebo

Sometimes called non-cebo/none-cebo though I avoid that as starting with “nonce” can be a trigger for the easily befuddled and offended (“Could you be experiencing a noncebo type effect?”, “WHAT DID YOU CALL ME?!”).

As the wikipedia page points out, this is not to be confused with knowcebo, which sounds the same. This is where information leaks break blinding measures and render test results less (or completely not) meaningful.