在蜈蚣賽局中風險成本、報酬不對稱性以及對手理性程度對決策的影響

Abstract

本研究的目的在探討在蜈蚣賽局中，報酬成長不對稱性、風險成本、對手的理性程度對決策的影響。76名大學生被隨機分配至三組風險成本不同（.90、.50、.20）的情境中，進行51局的蜈蚣賽局遊戲，其中32個遊戲涵蓋了2 (報酬不對稱性) × 2 (扮演角色) × 2 (金額大小) × 2 (對手理性程度)的實驗情境各兩個。結果發現，風險成本與金額大小有交互作用，在高風險成本且大金額的賽局中，參與者的合作行為會顯著下降。賽局的報酬成長率不對稱和扮演角色間有交互作用，報酬成長率不對稱會使參與者提早結束賽局，但對居於劣勢的B效果更大。金額大小與扮演角色間也有交互作用，不論金額大小，B結束賽局的時間點都較A早；弔詭的是A在小金額時會延長賽局結束的時間，反而是在大金額對他較有利時提早結束賽局，此結果顯示，居於優勢的A在報酬成長率不對稱且大金額的情況下，可能是擔心對手背叛而提前結束賽局。由研究結果顯示，人對於賽局中的報酬結構非常敏感，若在賽局中雙方的優劣勢差異過大時，合作意願就會降低。

The purpose of study was to examine the effects of the increment asymmetry in payoff, risk cost and rationality of the opponents on decision-making in centipede game. Seventy-six college students were randomly assigned to three risk cost conditions (20%, 50%, and 90%) to play 51 centipede games. Out of 51 games, 48 games were comprised by 2 increment asymmetry in payoff (symmetric vs. asymmetric in payoff increment) × 2 roles (A or B) × 2 amounts of money (large or small) × 2 levels of rationality of the opponent (rational vs. irrational) × 2 trials. Result shows that high risk cost (90% decrement) would decrease player’s decision to cooperate, but it only occurred when large sum of money was involved. Asymmetry in payoff increment would lead early abortion of the game for both players, but the effect was greater for B. In fact, the role x amount of money interaction showed that B, who was the more disadvantageous player in the games, tended to terminate the game earlier than A regardless of the amount of money involved. In contrast, A only terminated the game earlier when large sum of money was involved. It seems that A, who was the winner of the game, was afraid of being betrayed by B when the situation was most favorable to A. These findings suggest that people are highly sensitive to the structure of the game and would cooperate less when there is a large discrepancy in player’s utility from the game.