Authors: Muto, H., Nakai, R., Murai, T., Yoshikawa, S., & Abe, N.
(武藤拓之・中井隆介・ 村井俊哉・吉川左紀子・阿部修士)

Title: Baccarat gamblers follow trends rather than adhere to the gambler’s
fallacy: Analyses of field data from a casino.

Journal(書誌情報): Acta Psychologica, 258, Article 105172.

doi: 10.1016/j.actpsy.2025.105172

論文URL: https://doi.org/10.1016/j.actpsy.2025.105172

Abstract:
This study investigated the cognitive biases underlying baccarat gambling
behaviors through an analysis of 17,970,830 games played by 6625 customers
in a casino. Baccarat, a popular high-stakes game in East Asia, involves
predicting the outcome of two hands, where the results are inherently
unpredictable, similar to the structure of games such as roulette. In
contrast to existing theories predicting the emergence of the gambler’s
fallacy—or negative recency—when the outcome generation mechanism is
clearly random, most baccarat gamblers exhibit the opposite bias,
demonstrating a tendency toward positive recency. Specifically, customers
increasingly placed bets on future outcomes to match past consecutive
outcomes as streaks grew longer. This trend-following behavior diminished
when streaks were interrupted, ruling out explanations based on the “hot
outcome” fallacy, which is typically associated with adaptive behaviors
such as resource foraging. Moreover, betting amounts increased slightly but
reliably when gamblers followed trends. These findings provide new insights
into cognitive biases in gambling, challenge established theories of
positive and negative recency, and underscore the importance of considering
the unique structural characteristics of specific games when studying
gambling behavior. This perspective may also contribute to a deeper
understanding of pathological and problem gambling.

著者Contact先の email: mutopsy[at]omu.ac.jp (武藤拓之)（[at]を@に変更してください。）

日本語によるコメント:
カジノで得られた実データを分析してバカラ賭博者の賭け行動を調べた研究です。意思決定の理論では，ルーレットや宝くじのように，結果が明らかにランダムなプロセスによって決まるゲームにおいて，同じ結果が偶然に連続した後に反対の結果を予測するという認知バイアス(ギャンブラーの誤謬)が広く知られています。しかし本研究では，確率論的にはルーレットと類似のゲーム構造を持つバカラにおいて，それとはまったく逆のトレンド追従傾向が見られることを明らかにしました。本研究は，東アジアで特に人気の高いカジノゲームであるバカラに特有の賭け行動を実データに基づいて定量的に検証した（おそらく）世界初の論文です。また，これまでの多くの研究において混同されていたhot hand/outcome fallacyとpositive recencyを概念的に区別する必要性を示した点にも新規性があります。 （武藤）

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