Moving your mind the right amount
When a new clue arrives, almost everyone moves their answer a little less than the clue deserves.
A clue arrives: a marble from the jar, a fact in the news. It points somewhere.
There is an exact right amount to move your belief, and it can be worked out with counting.
Most people move less than that amount. Seeing your own moves next to the math is how the habit shifts.
Then and now
The bookbag experiments of the 1960s became a whole field: how far beliefs move against how far the arithmetic says they should.
Phillips, L. D. and Edwards, W. (1966)
Where it began“Conservatism in a simple probability inference task”
Journal of Experimental Psychology, 72, 346-354
Shown clues drawn from one of two known bags, people revised their beliefs in the right direction but reliably too little: the founding measurement of conservatism.
Benjamin, D. J. (2019)
State of the art“Errors in probabilistic reasoning and judgment biases”
Handbook of Behavioral Economics: Applications and Foundations, Volume 2, 69-186
The modern survey: across decades of experiments, under-reaction to new evidence remains one of the most consistent findings about human belief revision.
What we do and do not claim
Moving your answer the right amount is practice with counting, not a fixed talent, and this game measures only these jar puzzles.