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Research Article

Human Wagering Behavior Depends on Opponents' Faces

  • Erik J. Schlicht mail,

    schlicht@wjh.harvard.edu

    Affiliations: Department of Psychology, Harvard University, Cambridge, Massachusetts, United States of America, Department of Biology, California Institute of Technology, Pasadena, California, United States of America

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  • Shinsuke Shimojo,

    Affiliation: Department of Biology, California Institute of Technology, Pasadena, California, United States of America

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  • Colin F. Camerer,

    Affiliation: California Institute of Technology, Department of Economics, Pasadena, California, United States of America

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  • Peter Battaglia,

    Affiliation: Massachusetts Institute of Technology, Department of Brain and Cognitive Sciences, Cambridge, Massachusetts, United States of America

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  • Ken Nakayama

    Affiliation: Department of Psychology, Harvard University, Cambridge, Massachusetts, United States of America

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  • Published: July 21, 2010
  • DOI: 10.1371/journal.pone.0011663

Reader Comments (1)

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Your Research

Posted by caryw123 on 03 Aug 2010 at 02:29 GMT

Honesty this research does not show what it is claiming. If you participants are intelligent poker players they released that they are playing against a random hand, and the face has 0 effect on what hand it is. Therefore they should have called based on the EV vs. a random hand. If they believed it was a real situation they should have folded most of the time (>99%) because player is not going to bet 5000 into a 200 pot.

Suggestion, play poker and understand the dynamics of the game before you use it as the backbone of your study.

This study would be much better off as an observational study collecting data in the field, record real poker games and look at the faces and people actions.

The results presented are logical; a novice poker player would assume that someone who is happy/trustworthy is so for a reason, they know they are going to win.

Competing interests declared: I am a poker player

RE: Your Research

entropyy replied to caryw123 on 03 Aug 2010 at 15:08 GMT

I'm happy to hear from the poker community, but you must appreciate this is research. I do have a great understanding of the game of poker and the dynamics of the game. Therefore, it was a conscious decision to use a simplified version of poker (i.e., no position - heads-up, no re-raising, no stack-size considerations, no flop, turn, river, no feedback about outcomes to develop opponent models, etc.).

Although this greatly simplifies poker, it gains experimental control: we can more cleanly interpret our findings. What if I would have allowed for the addition information and found the same results? What could I say? At the end of the day, this is research! I must control for variables that I am not manipulating, so that I can interpret my findings.

Your comment that people should fold 99% of the time doesn't support your comment that people should have believed their opponent was random: I designed the hand distributions to have equal numbers of *optimal* call/fold decisions (against a random opponent). Therefore, folding 99% of the time, would clearly be a suboptimal strategy! In fact, that's why I used such a high raise amount: as bet size -> infinity, the optimal decision boundary approaches p(win) = .5.

What you may find interesting is that some people (perhaps like yourself) report not using face information at all. However, upon inspecting their data, it was clear they still folded at higher rates against a trustworthy appearing opponent, suggesting this effect may have an implicit factor.

The message I'd like you to walk-away with is that my decisions to simplify the poker game wasn't due to my lack of knowledge about the game, but rather my appreciation for its complexities. Good luck at the table!

No competing interests declared.

RE: RE: Your Research

entropyy replied to entropyy on 03 Aug 2010 at 15:11 GMT

p.s.,

"as bet size -> infinity, the optimal decision boundary approaches p(win) = .5."

this is for heads-up play against an opponent who bets randomly.

No competing interests declared.

RE: RE: Your Research

entropyy replied to entropyy on 03 Aug 2010 at 15:33 GMT

sorry, i misread your post. you were doing an 'either-or', and i comments only relate to your 'random opponent' scenario. so:

1. if people believed their opponents bet randomly, they should bet on ev of hand against random opponent. yes, however, people did not do this, and that's what's interesting! like i stated above, this could be a conscious strategy (see below) or an implicit reaction (i.e., people do not realize their using face information, which was clearly the case, with some).
2. your 99% fold would assume that 5000 chip bet ~ kk. however, it seems that people who may have used a conscious strategy just inferred a range of hands (which is more likely in 'real' poker) that are better than the untrustworthy or neutral opponents.
either way, these results are *very* consistent, so i'm also pleased/surprised!

No competing interests declared.