The paper presents a complete information model of bidding in second price sealed-bid and ascending-bid (English) auctions, in which potential buyers know the unit valuation of other bidders and may spitefully prefer that their rivals earn a lower surplus. Bidders with spiteful preferences...

People with a self-control problem often seek relief through social interactions rather than binding commitments. Thus, in self-help groups like Alcoholics Anonymous, Narcotics Anonymous etc, members are said to achieve better personal outcomes by mainly sharing their experiences. In other...