We study a type of complex system arising from economics, the lowest
unique bid auction (LUBA) system which is a new generation of online markets.
Different from the traditional auction in which the winner is who bids the highest price,
in LUBA, the winner is whoever places the lowest of all unique bids. In this paper,
we propose a multi-agent model to factually describes the human psychologies of the
decision-making process in LUBA. The model produces bid-price distributions that
are in excellent agreement with those from the real data, including the whole inverted-J
shape which is a general feature of the real bid price distribution, and the exponential
decreasing shape in the higher price range. This implies that it is possible for us to
capture the essential features of human psychologies in the competitive environment
as exemplified by LUBA and that we may provide significant quantitative insights into
complex socio-economic phenomena.

• The Psychological Force Model for Lowest Unique Bid Auction