The Aussie mega-meetup took place this past weekend. For it, a new kind of icebreaker was needed: one which is was not merely fun and sociable, but also instilled with the Way. Thus was the Credence Calibration Icebreaker forged.

A marriage of the credence game and the classic icebreaker, ‘Say three things about yourself, one of them a lie’, the game allows players to learn about each other, test their ability to deceive and detect deception, and discover just how calibrated they are.

How to play

Playing instructions here: docx pdf. Scoring spreadsheet.

Each turn a player makes three statements about themselves. One and only one the statement must be intentionally untrue. All others players assign probabilities of being false to each statement. These probability sum to 1: P(A’) + P(B’) + P(C’ ) = 1.  The game is scored in the same manner as the credence game, but with reference to 33% rather than 50%.

The way we played it, a player would reveal which was the lie immediately after everyone else had assigned probabilities. The immediate feedback is more fun and allows players to recalibrate as they learn about their performance. Revealing which statements were lies at the end would require reminding everyone what the other statements were.

Many meetup groups have played the Aumann agree game where groups collectively assign credences to a collection of statements, however that game requires a collection of statements to be collected in advance. Once played, new statements must be collected for a new game. The credence calibration icebreaker has the advantage that players generate the statements allowing for easy replay.

Improvements

Restrictions should be placed on the nature of the lies in order to control which skills are tested. We played without restrictions and most players generated a lie by altering a minor detail of a true statement which didn’t affect its plausibility, e.g. ‘My father’s brain is frozen’¹ vs. ‘My uncle’s brain is frozen’. This resulted in the game being less about appraising the plausibility of statements and more about detecting deception by tells and other clues.

Following the original icebreaker game, three statements were used. Reducing the number of statements to two would have the following benefits:

• The game is currently data entry intensive, requiring two numbers per question per player to be entered. Two statements would halve this number.
• Assigning probabilities of falsehood is counter-intuitive to many, using two statements would allow for the typical direct assignment of truth.
• People find generating three statements difficult, two statements would reduce the effort.

Statistics

Various statistics are computed in the scoring spreadsheet. Results from our game showed a high correlation between number correct and score, 0.72, and that players improved over the course of the game thanks to diminishing overconfidence.

1. True statement.  As was 'I have three kidneys'.