I am sorry but I can't find a study that concludes "humans prefer pay for work over the same pay for no work". You are just trying to overwhelm me to go and read a vast library of articles. I found a few studies where the "work" was lever-pushing and the study was with children where as they age they are less and less stupid exactly as expected (by me) http://www.amsciepub.com/doi/abs/10.2466/pr0.1981.49.3.859?j...

So please try to refer me to a study that I can apply in a general office environment with people aged 30 and a real-world job so we can check the claim.