title: Testing the social competition hypothesis of depression using a simple economic game.
abstract: BACKGROUND
  Price's social competition hypothesis interprets the depressive state as an unconscious, involuntary losing strategy, which enables individuals to yield and accept defeat in competitive situations.
  
  
  OBJECTIVE
  We investigated whether patients who suffer from major depressive disorder (MDD) would avoid competition more often than either patients suffering from borderline personality disorder (BPD) or healthy controls.
  
  
  METHODS
  In a simple paper-folding task healthy participants and patiens with MDD and BPD were matched with two opponents, one with an unknown diagnosis and one who shared their clinical diagnosis, and they had to choose either a competitive or cooperative payment scheme for task completion.
  
  
  RESULTS
  When playing against an unknown opponent, but not the opponent with the same diagnosis, the patients with depression chose the competitive payment scheme statistically less often than healthy controls and patients diagnosed with BPD.
  
  
  CONCLUSIONS
  The competition avoidance against the unknown opponent is consistent with Price's social competition hypothesis.
  
  
  BACKGROUND
  G.H. received research support, consulting fees and speaker honoraria from Lundbeck, AstraZeneca, Servier, Eli Lilly, Roche and Novartis.
  © The Royal College of Psychiatrists 2016. This is an open access article distributed under the terms of the Creative Commons Non-Commercial, No Derivatives (CC BY-NC-ND) licence.
authors.affiliation: , PhD, Psychiatric University Hospital, Division of Molecular Psychiatry, University of Bern, Bern, Switzerland.
authors.forename: Aleksandra
authors.initials: A
authors.lastname: Kupferberg
authors.affiliation: , MSc, Department of Psychiatry, Psychotherapy and Psychosomatics, Psychiatric Hospital; Laboratory for Social and Neural Systems Research, Department of Economics, University of Zurich, Zurich, Switzerland.
authors.forename: Oliver M
authors.initials: OM
authors.lastname: Hager
authors.affiliation: , Prof. Dr, Department of Economics, Economics University, Konstanz, Germany; Thurgau Institute of Economics, Kreuzlingen, Switzerland.
authors.forename: Urs
authors.initials: U
authors.lastname: Fischbacher
authors.affiliation: , MSc.
authors.forename: Laura S
authors.initials: LS
authors.lastname: Brändle
authors.affiliation: , DiplBiol.
authors.forename: Melanie
authors.initials: M
authors.lastname: Haynes
authors.affiliation: , MD, Prof., Psychiatric University Hospital, Division of Molecular Psychiatry, University of Bern, Bern, Switzerland.
authors.forename: Gregor
authors.initials: G
authors.lastname: Hasler