The Coin Jar Test

Three researchers at Carnegie Mellon found that warning people about a conflict of interest can leave them worse off than saying nothing at all. You can take their experiment right now. It takes about two minutes.

Here are the rules they used. You are the estimator. You will see a jar of coins for ten seconds, from across the room, and then guess what is in it. Before you guess, you get a suggestion from an adviser who was allowed to hold the jar and examine it closely.

The adviser knows more than you do. The adviser is also being paid. Whether that is a problem, and whether you are told about it, is the entire experiment.

Round 1 · Jar P

Ten seconds. Then guess.

Jar not yet presented

The jar will be visible for ten seconds only, exactly as in the original study.

Round 2 · Jar N

Same game. New jar. One addition.

Condition: disclosed
Jar not yet presented

A different jar, a different adviser. Ten seconds again.