Does Experience Affect Fairness and Reciprocity in Lab Experiments?

Date: 2016-07
By: Tiziana Medda (University of Cagliari)
Vittorio Pelligra (University of Cagliari)
Tommaso Reggiani (LUMSA University)
One of the most common criticisms about the external validity of lab experiments in economics concerns the representativeness of participants usually considered in these studies. The ever-increasing number of experiments and the prevalent location of research centers in university campuses produced a peculiar category of subjects: Students with high level of laboratory experience built through repeated participations in experimental sessions. We investigate whether the experience accumulated in this way biases subjects’ behaviour in a set of simple games widely used to study social preferences (Dictator Game, Ultimatum Game, Trust Game, and Prisoner’s Dilemma Game). Our main finding shows that subjects with a high level of experience in lab experiments do not behave in a significantly different way from novices.
Keywords: Experimental Methodology, External Validity, Experience, Lab Experiment
JEL: D03 D83 C91 C92

Individual Learning and Cooperation in Noisy Repeated Games

Date: 2013-07-06
By: Yuichi Yamamoto (Department of Economics, University of Pennsylvania)
We investigate whether two players in a long-run relationship can maintain cooperation when the details of the underlying game are unknown. Specifically, we consider a new class of repeated games with private monitoring, where an unobservable state of the world influences the payoff functions and/or the monitoring structure. Each player privately learns the state over time but cannot observe what the opponent learned. We show that there are robust equilibria in which players eventually obtain payoffs as if the true state were common knowledge and players played a “belief-free” equilibrium. We also provide explicit equilibrium constructions in various economic examples
Keywords: repeated game, private monitoring, incomplete information, belief-free equilibrium, ex-post equilibrium, individual learning
JEL: C72

Fairness norms can explain the emergence of specific cooperation norms in the Battle of the Prisoners Dilemma

Date: 2013-04-24
By: Fabian Winter (Max Planck Institute of Economics, Jena)
Cooperation norms often emerge in situations, where the long term collective benefits help to overcome short run individual interests, for instance in repeated Prisoner’s Dilemma (PD) situations. Often, however, there are different paths to cooperation, benefiting different kinds of actors to different degrees. This leads to payoff asymmetries even in the state of cooperation, and consequently can give rise to normative conflicts about which norms should be in place. This norm-coordination problem will be modeled as a Battle of the Sexes game (BoS) with different degrees of asymmetry in payoffs. We combine the PD and the BoS to the 3×3 Battle of the Prisoners Dilemma (BOPD) with several asymmetric cooperative and one non-cooperative equilibria. Bame theoretical and “behavioral" predictions are derived about the kind of norms that are likely to emerge under different shadows of the future and degrees of asymmetry and tested in a lab-experiment. Our experimental data show that game theory fairly well predicts the basic main effects of our experimental manipulations, but “behavioral" predictions perform better in describing the equilibrium selection process of emerging norms.
Keywords: Social norms, normative conflict, Prisoner’s Dilemma, coordination, experiment
JEL: Z13

Cooperation under the Shadow of the Future: Experimental Evidence from Infinitely Repeated Games

Bó, Pedro Dal (2005) “Cooperation under the Shadow of the Future: Experimental Evidence from Infinitely Repeated Games." American Economic Review, Volume 95, Number 5, December 2005 , pp. 1591-1604(14). ; 提供的 [PDF]  ; DOI: ;另見本站另一篇同作者在 2005AER 的文章


==notes by yinung==

本篇以有限重覆賽局 PD game 為對照,比較無限重覆賽局之影響。

主要針對 equilibrium actions and equilibrium outcome ,而非 equilibrium strategies (可能要參考 Dale O.  Stahl II (1991))

I focus on equilibrium actions and outcomes instead of equilibrium strategies,
I find that the percentage of outcomes in which both subjects cooperate is almost 19 percent when it is an equilibrium, whileit is less than 3 percent when it is not.


PD1                           PD2
=============================     =============================
          合作        背叛                  合作     背叛
 合作     (65, 65)   (10, 100)     合作     (75, 75)   (10, 100)
 背叛     (100,10)   (35, 35)      背叛     (100,10)   (45, 45)
=============================     =============================

有限賽局的設計(Finitely Repeated Games):

共有 1, 2,4 回合三種

子賽局均衡之推導,參見 Dale O.  Stahl II (1991)

the set of subgame perfect equilibria can be calculated using the results in Dale O.  Stahl II (1991).


…find strong evidence that the higher the probability of continuation, the higher the levels of cooperation.


針對 one-shot PD game; 合作率 9%; 無限重覆 (繼續機率=3/4) 合作率 38%。

…in the one-shot prisoner’s dilemma games studied here, the cooperation rate is 9 percent, for a probability of continuation of 3/4, it is 38 percent.

在有限重覆賽局中,也有終局效果 end-game effect,在最後一回合,合作率較低。

I find that the level of cooperation in the final round of the finitely repeated games is similar to the level of cooperation in one-shot games.


While there is an extensive literature on the theory of infinitely repeated games, empirical evidence on how “the shadow of the future" affects behavior is scarce and inconclusive. I simulate infinitely repeated prisoner’s dilemma games in the lab with a random continuation rule. The experimental design represents an improvement over the existing literature by including sessions with finite repeated games as controls and a large number of players per session (which allows for learning without contagion effects). I find that the shadow of the future matters not only by significantly reducing opportunistic behavior, but also because its impact closely follows theoretical predictions.


  • 子賽局均衡之推導和 rate of cooperation outcome 的定義 (??)
    Stahl, Dale O., II. “The Graph of Prisoner’s Dilemma Supergame Payoffs as a Function of the Discount Factor." Games and Economic Behavior, 1991, 3 (3), pp. 368 – 84.

The Evolution of Cooperation in Infinitely Repeated Games: Experimental Evidence

Dal Bó, Pedro ; Fréchette, Guillaume R. (2011) “The Evolution of Cooperation in Infinitely Repeated Games: Experimental Evidence." The American Economic Review, Volume 101, Number 1, February 2011 , pp. 411-429(19). DOI:; 提供的 [PDF] ; Download Data Set (355.92 KB) | Online Appendix (284.08 KB);

==notes by yinung==

此文用的 PD game,進行無限重覆賽局的實驗。see also 另一篇也在 AER 2005 年刊出的和有限重覆 PD game 之比較(或參目本站的另一篇 note)。

          合作     背叛
 合作    (R, R)   (12, 50)
 背叛    (50,12)  (25, 25)
繼續玩之機率:1/2, 3/4


The 18 experimental sessions were conducted between July 2005 and March 2006. A total of 266 New York University undergraduates participated in the experiment, with an average of 14.78 subjects per session, a maximum of 20 and a minimum of 12. The subjects earned an average of $25.95, with a maximum of $42.93 and a minimum of $16.29. In the treatments with δ =
1/2 and δ = 3/4 the average number of rounds per match was 1.96 and 4.42 respectively, and the maximum was nine and 23 respectively.


…each subject participated in between 23 and 77 infinitely repeated games

…Previous experimental evidence has shown that subjects often fail to coordinate on a specific equilibrium when they play a small number of infinitely repeated games



…the level of cooperation decreases with experience and converges to low levels

…the level of cooperation does not necessarily increase and may remain at low levels even after significant experience is obtained.

…this evidence suggests that while being an equilibrium action may be a necessary condition for cooperation to arise with experience, it is not sufficient.

若 cooperation 是 risk dominant, 則合作隨著經驗增加而上升

If we consider together all sessions for which cooperation is risk dominant, we find that cooperation increases on average as subjects gain experience….Risk dominance has been used as a selection criterion in the study of coordination games.


…These results show how difficult it is for experienced subjects to sustain high levels of cooperation. They cast doubt on the common assumption that agents will make the most of the opportunity to cooperate whenever it is possible to do so in equilibrium.

…In fact the impact of repetition on rates of cooperation was rather modest, leading Roth to conclude that the results are equivocal (Roth 1995). (註:這些結果皆來自於隨機結束的賽局 randomly terminated game. All of these papers used games with a randomly determined length.)


A usual criticism of the theory of infinitely repeated games is that it does not provide sharp predictions since there may be a multiplicity of equilibria. To address this issue, we present experimental evidence on the evolution of cooperation in infinitely repeated prisoner’s dilemma games as subjects gain experience. We show that cooperation may prevail in infinitely repeated games, but the conditions under which this occurs are more stringent than the subgame perfect conditions usually considered or even a condition based on risk dominance.


  • Bereby-Meyer,Yoella, and Alvin E. Roth. 2006. “The Speed of Learning in Noisy Games: Partial Re-inforcement and the Sustainability of Cooperation.” American Economic Review, 96(4): 1029–42.
  • Dal Bó, Pedro. 2005. “Cooperation under the Shadow of the Future: Experimental Evidence from Infinitely Repeated Games.”American Economic Review, 95(5): 1591–1604.
    這篇比較無限和有限重覆 PD game, 發現無限重覆賽局,在同樣條件下會有較高的合作率

    [this paper] compares infinitely repeated and finitely repeated prisoner’s dilemma games of the same expected length and finds that cooperation is larger in the former as theory predicts.
  • Dal Bó, Pedro. 2007. “Tacit Collusion under Interest Rate Fluctuations.” RAND Journal of Economics, 38(2): 533–40.

Rational cooperation in the finitely repeated prisoner’s dilemma: Experimental evidence

Andreoni, J, Miller JH (1993) Rational cooperation in the finitely repeated prisoners’ dilemma: experimental evidence. Econ J 103: 570–585.  CrossRef

==from Google==
In the finitely repeated prisoner’s dilemma, it is well known that defection in every game is the unique dominant-strategy Nash equilibrium. This follows from the familiar backward-induction arguments. Kreps et al. (i 982), however, show that if there is incomplete information …
被引用 386 次相關文章全部共 14 個版本; 提供的 [PDF]

==notes by yinung==

此文沒有提及全部平均合作率, 只有 Figure 3 講到最後 2個 10 回合 PD game 結果

partners => 86% (1st round), above 50% (4-6 round), 0% (最後)

4 種情境 (皆玩 20 個 10回合之 PD game

  • Partners (14人, 兩人一組)

每回合對手皆相同 (電腦隨機決定配對之對手, 此後…)

  • Strangers (14人, 兩人一組)


  • Computer50

電腦報復 (tit-for-tat) 機率 50%

  • Computer0

電腦報復機率 1/1000

Matrix of the game

          合作     背叛
 合作     (7, 7)   (0, 12)
 背叛     (12,0)   (4, 4)

The impact of the termination rule on cooperation in a prisoner’s dilemma experiment

Hans-Theo Normann, Brian Wallace (2012) “The impact of the termination rule on cooperation in a prisoner’s dilemma experiment." International Journal of Game Theory, August 2012, Volume 41, Issue 3, pp 707-718. link to Springer; working版本 提供的 [PDF] 提供的 [PDF]

Note by yinung

這篇原是 DICE 的 working paper (see 本站另一篇 PO 文),現在刊出來了。

主要結論 (in abstract):

此文研究3種 PD game 實驗回合結束的方式 (告知結束回合、不告知結束回合、隨機結束),比較合作率之不同。 1. 三種結束方式不影響合作率 2. 隨機結束方式不會提高合作率 (相對於告知結束回合);不同繼續玩 (隨機結束) 之機率高低 (continuation probability) 亦不影響合作率 3. 結束方式會影響 over time 和 end-game 行為 4. 預期玩的回合愈長,合作率愈高


三種 termination rule:

  • finite horizon: Flood (1952) and Rapoport and Chammah (1965) … it is well known that stable cooperation does occur also in finitely repeated games
  • unknown horizon: Fouraker and Siegel 1963
  • random-stopping rule: to terminate the experiment (Roth and Murnighan1978; Axelrod 1980)

End-game effects: Morehous (1966) … defection rates increase towards the end of the game when the horizon of the game is known to be finite. … used a probabilistic termination rule so that “end-game effects were successfully avoided” (Axelrod 1984, p. 42). Murnighan and Roth (1983, p. 284) argue that “consideration of end-game play is less critical” with the random termination rule. Holt (1985, p. 320) makes the same point. 也有人在分析結果時,去掉最後幾回合 贊同應用隨機結束 With finitely many periods, the theory is bland; by contrast, the random termination rule “permits the nature of the equilibrium outcomes to be controlled” (Roth and Murnighan 1978, p. 191) Selten and Stoecker (1983) further noted that subjects learn to anticipate the endgame effect in that this effect is shifted to earlier rounds when a supergame with a finite horizon is repeated several times (see also Andreoni and Miller 1993) 隨機結束機率高者,使合作率較高 (與本文結果不一致),但重覆的實驗不能確定此一結果 Roth and Murnighan (1978) found that a random stopping rule with higher continuation probability does lead to more cooperation in the prisoner’s dilemma. However, in the modified setup analyzed in Murnighan and Roth (1983), this could not be confirmed. Dal Bo (2005) 發現隨機結束機率(在 supergame 玩 10 次後) 有重要影響


至少玩 22 回合 (??? 不知何義,待了解… 因為結束回合數不一定一樣), 4 情境、每情境有15組人

  • Know
  • Unknow
  • RandomHigh (5/6 繼續機率)
  • RandomLow (1/6 繼續機率)

supergame 不重覆 (??)Subjects were rematched after the first supergame. 另外有 Shorter Horizon 額外較短實驗

  • Known5 (9組,2人一組)
  • Known10 (11組)
  • Random5+5 (11組;至少5回,5/6 繼續機率,平均期望值=10回,恰與 Known10 對照)

合作率 要小心合作率的定義!(各文獻不一定相同) 其 Table 2 中的合作率是 cooperte choices (不是 cooperate outcome, 所以22回合中才最多有 44 個 cooperate choices) 此文皆是利用 cooperate choice 來分析,Harvey Wichman (1970, J of Personality and Social Psychology) 也是用此定義 有的文獻合作率的數字是 cooperate outcome (兩人皆是 cooperate choice 才算合作) (引文)…In order to take the possible dependence of observations between paired players into account, we count each participating pair as one observation. Matrix of the game 從合作到背叛,邊際利得只有 1000-800 = 200, 反而對手損失 750 較多;若因此而雙方開始不合作,每期邊際損失 250,根本不值得背叛;但是一旦被背叛,當次邊際損失 700, 要3次背叛才得以報復。

       背叛              合作 
背叛  (350, 350)      (1000, 50)
合作  (50, 1000)      (800, 800)

文中所述之 5 個 results

  • Result 1. The termination rule does not significantly affect average cooperation.

2種隨機結束和告知回合、不告知 等 treatment 合作率無顯著不同 (Kruskal-Wallis test)

  • Result 2. There is a negative and significant time trend in treatments Known and RandomLow.

Known 和 RandomLow 合作率有下降趨勢 (significant time trend)

  • Result 3. A significant end-game effect occurs in all treatments except Unknown。
2種隨機結束和告知回合都有 End-game effect (在最後幾回合作率顯著逐漸下降的情況)。 折現率~= 4/13 時,{C,C} is a subgame perfect Nash equilibrium outcome of the infinitely repeated game if and only if the discount factor is larger than 4/13 ~ 0.31.
  • Result 4 The termination rule does not significantly affect average cooperation rates in treatments Known5, Known10, Random5+5.
  • Result 5 The length of the horizon of the game significantly increases cooperation rates.


Kruskal-Wallis test
Testing for differences in cooperation with all treatments jointly does not suggest significant results


Cooperation in prisoner’s dilemma games can usually be sustained only if the game has an infinite horizon. We analyze to what extent the theoretically crucial distinction of finite versus infinite-horizon games is reflected in the outcomes of a prisoner’s dilemma experiment. We compare three different experimental termination rules in four treatments: a known finite end, an unknown end, and two variants with a random termination rule (with a high and with a low continuation probability, where cooperation can occur in a subgame-perfect equilibrium only with the high probability). We find that the termination rules do not significantly affect average cooperation rates. Specifically, employing a random termination rule does not cause significantly more cooperation compared to a known finite horizon, and the continuation probability does not significantly affect average cooperation rates either. However, the termination rules may influence cooperation over time and end-game behavior. Further, the (expected) length of the game significantly increases cooperation rates. The results suggest that subjects may need at least some learning opportunities (like repetitions of the supergame) before significant backward induction arguments in finitely repeated game have force.


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  10. Dal Bo P (2005) Cooperation under the shadow of the future: experimental evidence from infinitely repeated games. Am Econ Rev 95: 1591–1604 CrossRef
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Behavioral Approach to Repeated Games with Private Monitoring

Date: 2013-03
By: Hitoshi Matsushima (The University of Tokyo)
Tomomi Tanaka (Economic Development & Global Education, LLC)
Tomohisa Toyama (Kogakuin University)
We examine repeated prisoners’ dilemma with imperfect private monitoring and random termination where the termination probability is low. We run laboratory experiments and show subjects retaliate more severely when monitoring is more accurate. This experimental result contradicts the prediction of standard game theory. Instead of assuming full rationality and pure self-interest, we introduce naivete and social preferences, i.e., reciprocal concerns, and develop a model that is consistent with, and uniquely predicts, the observed behavior in the experiments. Our behavioral model suggests there is a trade-off between naivete and reciprocity. When people are concerned about reciprocity, they tend to make fewer random choices.

Laboratory Evidence on Face-to-Face: Why Experimental Economics is of Interest to Regional Economists*

Björn Frank (2012) “Laboratory Evidence on Face-to-Face: Why Experimental Economics is of Interest to Regional Economists." International Regional Science Review, June 13, 2012. doi: 10.1177/0160017612449017. working paper PDF; Journal Web. **

Notes by yinung

此文提及 death of distance" (Cairncross, 2001) or “death of geography" 意思是

…the shrinking costs for transportation, especially transportation of messages’ pure in formation content.

必需有 face-to-face 溝通的原因是

… widely agreed that communication often must be face-to-face in order to be effective. But why?

1. nonverbal 和 verbal 同時發生,減少誤解(Storper and Venables, 2004; Winger, 2005, sections 4 – 6; and Hildrum, 2007, p. 469 with further references).

2. 比較有意義 (???待了解)

3. 發現想看到的,也發現原來沒想看到的隱含事務

4. buzzing (流言???)

5. face-to-face 溝通成本高,可視為建立長期關係之投資

6. 建立互信的必要條件

以上是理論,經濟實驗 (不含心理實驗)之證據為此文之回顧重點

匿名實驗結果有時不具參考性,此文同意此觀點 (至少用 email 溝通知道名字)

幾個與 face-to-face 相關因素

  1. 即時回應之效果 and 冷淨作用 Cooling effects: effect of spontaneity (decision time)  in Sec. 2
  2. trust 和合作受到 face-to-face 之影響 in Sec. 3
  3. 細節因素,如 smiling 和 eye contact  在 f2f 中之角色


..experiment on the effect of a substantive cooling off period in an experiment was invented by Oechssler, Roider and Schmitz (2008).

在 ultimatum game 中,8:2 和 5:5 的分餅被提出,看對手是否接受。24小時後,接受的決定可以被修改。餅獎金大小分別有 2,5,8 euros. Cooling off period 並未導致拒絕率大幅降低 (from 42.6% to 39.4%) ,且不顯著。但將 reward 變大 (期望值相同,用 lottery 方式),則拒絕率顯著大幅下降 fom 27.7% to 20.5%.

增加決策時間之壓力也有同樣的效果 (提高拒絕率) increased time pressure might well increase the rejection rate by Sutter, Kocher and Strauß (2003). 決策時間減少 (100秒 mm> 10 秒),拒絕率增加從 40.3 to 78.2%。 Cappelletti, Güth and Ploner (2008) 也有類似的發現 (180秒 vs 30 秒)。情感區 (affective system) 和 (deliberative system) 在大腦中並不相同。


在 UG 中,拒絕率上升,代表效率下降。出價者將會喜歡拒絕率降低 (因此可降低 offer); 反之,回應者將喜歡拒絕率上升。故,出價者將偏好 face-to-face 溝通。不過要注意的是 UG 是單向一次 negotiation, 一般的談判會有雙向回應

建立互信 & 合作

Valley, Moag and Bazerman (1998)

(註: 有時互信和合作很難區分 see


只有 seller 知道 V; Seller 會接受 if B>V; seller 得到 (B-V);

Buyer 只知 V~uniform(0,100), 真實 V 要等 Buyer 買到以後才知道。真實價值 = 1.5V; buyer 得到 (1.5V-B);

Buyer 問 seller V=?, 但 seller 可以 lie; 不過 face-to-face 之下,seller 顯著地比較不可能 lie (face-to face 只有 1 of 14, 7% lie; 電話 55% lie; 不匿名witten 33% lie). 有些 face-to-face 的 buyer 並沒有問 seller V;

結果發現 face-to-face 導致比較多的 Pareto improving deals.

Pareto deals (雙方皆獲益)

face-to-face: 51.7% (out of n=21) 成交; 顯著大於 written comm. 但不顯著大於 telephone comm.

written comm.: 22.2% (未成交 52% 接近理論值)

telephone comm.: 38.1%

Non-Pareto deals (buy’s loss):

face-to-face: 23.8%

written comm.: 25.9%

telephone comm.: 47.6%

Frohlich and Oppenheimer (1998) PD game (應是 public good game)

5人一組玩多人 PD game 共 15 回合; 前 8 回合用 (a) 事先沒有 comm.; (b) email (c) face-to-face;

每人在每回合決定貢獻 0~10 給 group, 留下其餘。

S=5人貢獻之加總; 每人皆領回 0.4S

理論:每人皆貢獻 10, 則 S = 50,每人皆領回 0.4S = 20; 若每人皆貢獻 0, 則每人只得 10


各 treatment 之平均貢獻 (前 8回合

(a) 沒有 comm: 2.9

(b) email: 7.6

(c) face-to-face: 9.99

9回合以後(皆沒有 comm.)

Contributions in groups with previous face-to-face communication quickly collapse to the level of the e-mail-groups.

face-to-face 效果持續多久

一回合就夠了? (Brosig, Ockenfels and Weimann, 2003; Bochet et al., 2006)

Rocco (1998).

6人一組玩28回合的 public good game;在第 10,15,20加入 face-to-face comm.;

每一回合貢獻 x of 13 tokens; 全部人之貢獻加總= S; 每人之 Payoffs = ???

face-to-face comm. 有助於 maximize group welfare 在後半段實驗; Email comm. 並沒有較高的合作;但實驗前一天 email comm. 的人 face-to-face 之後,卻有類似的效果。

Bochet et al. (2006)

4人10回合的 PG game;比較 5分鐘的實驗前 face-to-face vs 第 1,4,7回合 online 討論 in a chat room;


兩者差異沒有後大, 其平均貢獻:

chat room: 81.4%

face-to-face: 96.2%

但在第10回合有 drop, chat romm ->52.1%; face-to-face -> 78.1

Naquin, Kurtzberg and Belkin (2008),

玩 threshold PG game; 4 人一組;若至少有 3人 捐出 1 張餐券,則每人獲兩張 ¥7餐券 2 張;

比較 非匿名之 email 和 face-to-face 決策:

email: 35.8% of the participants 捐出

face-to-face: 69.9%


Brosig, Ockenfels and Weimann (2003)

4人一組,10回合 PG game; 其貢獻 of endowment

audio comm.: 48%

anonymous: 57%

video comm: 93%

face-to-face: 97% (後兩者顯著高於前兩者)

照片 出現 10 秒: 貢獻率低於 anonymous

Face-to-face 可能隱含的影響因素


Scharlemann et al. (2001) 在 trust game 中,發現微笑有助於合作

 Player 1 — [$1, 0.5]
Player 2 — [0.8, 1.25]
Player 1 — [1.20, 1.20]

Player 1 是受試者,Player 2 是電腦但 show 照片 (treatment 是否微笑,取自相片資料庫),只要 Player 1 選擇 trust 策略,則電腦 (Player 2) 必定也用 trust 回應。結果發現, Player 1 之回應

沒有微笑: 55.0% 選擇 trust 策略
有微笑:     68.3%

eye contact

Burnham and Hare (2007)

4人一組,6回合 PG game (對手不重覆); 其貢獻 of endowment ~ (0, 10,相當於 2 美金), 總貢獻*2 均分給 4 人.

實驗組看到金屬臉但具有人類眼睛的影像 (MIT 發明的 “Kismet” robot), 實驗結果:

匿名:        4.17

Haley and Fessler (2005)
玩 dictator game, 分$10美金, 實驗組看到眼睛圖片,對照組看到 label, 結果

Player 1 分給 Player 2

Bateson, Nettle and Roberts (2006)現地實驗中也發現,eye contact 會讓貢獻較多錢

在48位大學職員喝咖啡處貼眼睛海報 or 花海報各幾週,自願投幣奉獻 (honesty box) 金額


Frey and Bohnet (1995) 在 PD game 中讓受試者選擇合作和背叛,合作率

visual contact + talking : 78%
visual contact + no talking : 23%

Wichman (1970) 在 PD game 中讓受試者選擇合作和背叛; 70回合,固定對手,合作率

無限制的 face-to-face: 87%
互聽到聲音: 72.1%
只有 visual contact: 47.7%


The notion of face-to-face contacts has recently become very popular as a reason why firms still locate in proximity to others after the “death of distance.” Controlled laboratory experiments provide direct and reliable evidence on the importance of face-to-face contacts. It is the purpose of this article to survey and to organize new and developing string of literature with a special focus on its importance for regional economics. However, the article might also serve to alert more experimentalists to the importance of their work for current regional science, of which they seem not to be aware.

References (部份)

  • 冷卻效果
    Oechssler, Jörg, Andreas Roider and Patrick Schmitz (2008), Cooling-Off in Negotiations – Does It Work?, mimeo:
  • 決策時間長短 in Ultimatum game
    Sutter, Matthias, Martin Kocher and Sabine Strauß (2003), Bargaining under time pressure in an experimental ultimatum game, Economics Letters 81, 341–347.
  • Cappelletti, Dominique, Werner Güth and Matteo Ploner (2008), Being of two minds: an ultimatum experiment investigating affective processes, mimeo.
  • 其它
    Bateson, Melissa, Daniel Nettle and Gilbert Roberts (2006), Cues of being watched enhance cooperation in a real-world setting, Biology Letters 2, 412–414.
  • Bochet, Olivier, Talbot Page, and Louis Putterman (2006), “Communication and Punishment in Voluntary Contribution Experiments," Journal of Economic Behavior and Organization, 60, 11-26.
  • Bohnet, Iris and Bruno S. Frey (1999), The sound of silence in prisoner’s dilemma and dictator games, Journal of Economic Behavior & Organization 38, 43-57.
  • Brosig, Jeannette, Axel Ockenfels and Joachim Weimann (2003), The effect of communication media on cooperation, German Economic Review 4, 217-241.
  • Burnham, Terence C. and Brian Hare (2007), Engineering Human Cooperation. Does Involuntary Neural Activation Increase Public Goods Contributions?, Human Nature 18, 88-108.
  • Frey, Bruno S. and Iris Bohnet (1995), Institutions Affect Fairness: Experimental Investigations, Journal of Institutional and Theoretical Economics 151, 286-303.
  • Frohlich, Norman and Joe Oppenheimer (1998), Some consequences of e-mail vs. face-to-face communication in experiment, Journal of Economic Behavior & Organization 35, 389-403.
  • Haley, Kevin J. and Daniel M.T. Fessler (2005), Nobody’s watching? Subtle cues affect generosity in an anonymous economic game, Evolution and Human Behavior 26, 245–256.
  • Naquin, Charles E., Terri R. Kurtzberg and Liuba Y. Belkin (2008), E-Mail Communication and Group Cooperation in Mixed Motive Contexts, forthcoming: Social Justice Research,
  • Rocco, Elena (1998), Trust Breaks Down in Electronic Contexts but Can Be Repaired by Some Initial Face-to-Face Contact, Proceedings of the SIGCHI conference on Human factors in computing systems 1998, 496-502.
  • Scharlemann, Jörn P.W., Catherine C. Eckel, Alex Kacelnik and Rick K. Wilson (2001), The value of a smile: Game theory with a human face, Journal of Economic Psychology 22, 617-640.
  • Valley, Kathleen L., Joseph Moag and Max H. Bazerman (1998), ‘A matter of trust’: Effects of communication on the efficiency and distribution of outcomes, Journal of Economic Behavior and Organization 34, 211-238.
  • Valley, Kathleen, Leigh Thompson, Robert Gibbons and Max H. Bazerman (2002), How Communication Improves Efficiency in Bargaining Games, Games and Economic Behavior 38, 127-155.
  • Wichman, Harvey (1970), Effects of Isolation and Communication on Cooperation in a Two-Person Game, Journal of Personality and Social Psychology,16, 114-120.; DOI;


PD game
Frey and Bohnet (1995) J Inst. & Theo. Econ.
visual contact + talking : 78%
visual contact + no talking : 23%
Wichman (1970) J Per & Soc Psy
無限制的 face-to-face: 87%
互聽到聲音: 72.1%
只有 visual contact: 47.7%
Oechssler, Roider and Schmitz (2008)
Sutter, Kocher and Strauß (2003) EL
Cappelletti, Güth and Ploner (2008) mimeo

dictator game
Haley and Fessler (2005)

Trust game
Valley, Moag and Bazerman (1998) JEBO
Scharlemann et al. (2001) (smiling 在 trust game 中) JEPsy

Public good game
Frohlich and Oppenheimer (1998) JEBO
Rocco (1998) Proceedings of the SIGCHI conference
Bochet et al. (2006) JEBO
Brosig, Ockenfels and Weimann (2003) GER
Burnham and Hare (2007) (眼睛 contact) Human Nature

Bateson, Nettle and Roberts (2006) 在現地實驗(自助咖啡投幣)

Friend or Foe? A Natural Experiment of the Prisoner’s Dilemma*

John A. List (2006) “Friend or Foe? A Natural Experiment of the Prisoner’s Dilemma."  August 2006, Vol. 88, No. 3, Pages 463-471. Posted Online October 4, 2006. (doi:10.1162/rest.88.3.463); NBER; 提供的 [PDF]

Notes by yinung

  1. 這是用一個  Friend or Foe game show 參賽者所玩的 PD game 的資料所寫成的 paper; 其實驗發現重點摘要如下:
  2. 25% (of 117 場),雙方皆選擇 “不合作”, 因此得 0 (未拿走的獎金累計 100,000美元)約 25% 雙方皆選擇 “合作”
  3. 獎金多寡不影響實驗策略選擇之結果
  4. 個人合作率顯示無 social discrimination 存在;但選擇 partner 的資料卻顯示 biased against 年紀大的參賽者


This study examines data drawn from the game show Friend or Foe? which is similar to the classic prisoner’s dilemma tale: partnerships are endogenously determined, and players work together to earn money, after which they play a one-shot prisoner’s dilemma game over large stakes: varying from $200 to (potentially) more than $22,000. The data reveal several interesting insights; perhaps most provocatively, they suggest that even though the game is played in front of an audience of millions of viewers, some of the evidence is consistent with a model of discrimination. The observed patterns of social discrimination are unanticipated, however.

Friend or Foe