Bargainers must generally attempt to judge their counterparts' preferences,
beliefs, and alternatives to settlement. Both descriptive and prescriptive
theorists have assumed that an accurate perception of the other bargainer'
s reservation price (r.p.) is advantageous. Yet, unbiased judgments are opt
imal only when the costs of underestimation and overestimation are symmetri
c. Optimistic bias has been found to have adaptive value in judgments relat
ed to other types of tasks. In two studies we examined the relationship bet
ween perceptions of the bargaining zone and settlements in essentially dist
ributive bargaining games. In the largely exploratory study one, bargainers
were generally optimistically biased (i.e., they thought their counterpart
could concede more than s/he really could) and optimism was positively cor
related with profitability. In study 2 we manipulated information to induce
accurate or biased perceptions. Optimistically biased negotiators again re
ached more profitable settlements than accurate or pessimistically biased n
egotiators. Optimism did not increase the likelihood of impasse in either s
tudy. Nor did it damage the relationship between the parties. Initial optim
ism appears to play an adaptive role in bargaining.