It sounds crazy but most sound engineers have accidentally done this to themselves. You tweak a knob, hear the difference, and then noticing the whole channel was muted and wonder what it was that you just heard change.
I was once debugging some issue with my laptop's multimedia buttons driver. I found some tweak which helped: enable the tweak, reboot - works fine, disable tweak, reboot - no go. Tested repeatedly several times.
I filed a bug report and received an answer that my tweak absolutely cannot work. The tweak was disabled at the time and the button didn't work. I pressed it again after reading this email and boom - it works.
I swear.
I figure my mind must have been believing so much in futility of pressing this button that it didn't even bother pushing it all the way down. Scary stuff.
This is kind of the same idea as throwing in a duck[1] or hairy arms[2]:
1: http://blog.codinghorror.com/new-programming-jargon/ 2: http://www.oliverburkeman.com/blog/posts/the-theory-of-the-h...