Gneezy, Uri, and Aldo Rustichini, (2000). "Pay enough or don't pay at all," The Quarterly Journal of Economics, 115(3): 791-810.
The effect of monetary compensation on performance was not monotonic. In the treatments in which money was offered, a larger amount yielded a higher performance. However, offering money did not always produce an improvement: subjects who were offered monetary incentives performed more poorly than those who were offered no compensation.
Gneezy, Uri, and Aldo Rustichini, (2000). "A fine is a price," The Journal of Legal Studies, 29(1): 1-17.
Presents the result of a field study that contradicts the prediction that the introduction of a penalty will reduce the occurrence of the behavior subject to the fine. The implementation of a monetary fine for late-coming parents raised the number of late-coming parents significantly. After the fine was removed no reduction occurred.
Iizuka, Toshiaki, and Hitoshi Shigeoka. 2022. "Is Zero a Special Price? Evidence from Child Health Care." American Economic Journal: Applied Economics, 14 (4): 381-410.
Do consumers react differently to zero prices? The authors test the presence of a zero-price effect in child health care and find that a zero price is special because it boosts demand discontinuously, relative to a small co-payment as small as US$2 per visit. Therefore, zero and non-zero prices should be strategically chosen to achieve specific goals.