Quick note of caution on changing the incentive rate downwards. If you might be sampling in times/places where people have previously experienced the higher incentive, this might trigger a loss framing for people. I.e., if you move to the busier time that will eventually be your normal collection time and location, and give the people who are around then the perception that $5 is the normal compensation they'll get, when that drops to $1 they'll maybe be less inclined to contribute their sample than if they'd never seen the $5 option.
Maybe you could moderate that effect by some creative design like the board saying $1 prominently, then appending "special today $5" somehow in a way that clearly communicates it's a special temporary extra.
Checking about 2 years after my initial post, it looks like $TSLA has fallen by more than 50%: it looks like the split-adjusted price in early April 2022 was around $330 or $340, and today it's around $145.
Eyeballing the chart, it looks like it's always been lower than that in the subsequent period, and was down to around $185 at the 12 month mark that was initially the target of the competition. That last bit is the bit that was least clear to me at the time: it seemed high probability that Tesla stock would have to fall at some point, but I expressed uncertainty about when because I thought there was a fair probability the market could stay irrational for a longer period.
There’s this nice paper where a load of different researchers are given the same (I think simulated) data and looked at how researchers result.
Might the research you were thinking of be the work by raphael Silberzahn, Eric L. Uhlmann and Brian Nosek?
Nature comment: https://www.nature.com/articles/526189a
Full research article: https://journals.sagepub.com/doi/10.1177/2515245917747646
Are either of these relevant?
https://www.lesswrong.com/posts/x4dG4GhpZH2hgz59x/joy-in-the-merely-real
https://www.lesswrong.com/posts/Hs3ymqypvhgFMkgLb/doublethink-choosing-to-be-biased