Incomplete vs. Imperfect Information

Incomplete and imperfect information are two important concepts in game theory. They are similar but have quite different meanings.

Under imperfect information, players are simply unaware of the actions chosen by other players. However, they know who the other players are, what their possible strategies/actions are, and the preferences/payoffs of these other players. For example, you may not be able to perfectly observe the actions chosen by the other players (imperfect monitoring), or the implemented actions of other players may be different from their intentions.

Under incomplete information, players may or may not know some information about the other players, e.g. their “type”, their strategies, payoffs etc.

Social Distance and Judgment Biases

Judgment biases are consistently observed when people evaluate probabilistic information. Specifically, people usually overrate events that are unlikely to happen, such as winning five million on the lottery, having a child with a genetic disease, or being involved in a traffic accident. Such overrating leads to impulsive purchase of lottery tickets and overinvestment in insurance. The emergence and reduction of these judgment biases needs to be investigated to help people make rational decisions.

Judgment biases become inevitable when decision makers become too attached to certain outcomes (Williams, Stein, & Galguera, 2014). Therefore, such biases can potentially be reduced by increasing the social distance between the decision maker and the beneficiary. Such principle is well recognized in the medical profession. For example, the Ethics Manual of the American College of Physicians prescribes that physicians must avoid treating themselves, close friends, or family members (Snyder, 2012). Similarly, the Code of Medical Ethics of the American Medical Association suggests that physicians must not treat themselves or members of their immediate families because their personal feelings may unduly influence their professional medical judgment, thereby interfering with the care being delivered (American Medical Association, 2014).

In one of my research project, my coauthors and I investigate whether increased social distance can reduce judgment biases. As it turns out, social distance can indeed reduce these biases, because as the social distance increases, people are less stimulated emotionally, making them better utilize available information to make better decisions.

An Anecdote about chess and Napoleon

An escape plan had been hatched whereby a French soldier would bring a chess set to Napoleon. Inside one of the pieces were hidden plans to help him escape. The soldier never made it to St. Helena, dying of a heart attack while the ship was enroute. So Napoleon never found out about the plans, even though he played the chess all the time.