This was a research project to investigate:
The game ran on quiz.worldofuncertainty.org for a year. 500 people played the game and answered questionnaires, proving that you can significantly, but slowly, improve your skill at estimating your own uncertainty, as explained in the Ph.D. thesis of Jyldyz Tabyldy kyzy at Queen's University Belfast
Take a look at the World of Uncertainty reseach proposal. It had been funded by the EPSRC.