"punkalouver, I remember, many years ago when I was a fairly new co-pilot, reaching for the flap lever on a VC10 instead of the U/C lever soon after take-off and realising it just in time. I had my hand on the lever and had grasped it but I don't think anyone else noticed - it shocked me when I realised what I had so very nearly done. Unfortunately, I think we are all vulnerable to irrational actions at times. Therefore, the mantra others have stated, always to look and identify before taking action is highly relevant. It was certainly a lesson for me which I never forgot."
Oddly it can also happen after you've been doing the same action(s) for years. I've seen people reach out oo pull a wrong leaver or switch after 10+ years of faultless operation. Sometimes the brain/muscle memory seems to just fail