title: Processing of fair and unfair offers in the ultimatum game under social observation.
abstract: Social context influences social decisions and outcome processing, partially depending on inter-individual differences. The present study investigated social context-dependent modulation of behavior and feedback processing in the ultimatum game (UG) in relation to inter-individual differences in social anxiety. Thirty-two healthy adults completed the UG both under social observation and without observation. Offers were allegedly either randomly generated by the computer or drawn from a pool of offers from previous human players. Overall, fewer unfair than fair offers were accepted. Observation decreased acceptance rates for unfair offers. The feedback-locked feedback-related negativity (FRN) but not the P3 was modulated by observation and fairness, with stronger differential coding of unfair/fair under observation. This effect was strongly correlated with individual levels of social anxiety, with higher levels associated with stronger differential fairness coding in the FRN under observation. Behavioral findings support negative reciprocity in the UG, suggesting that (implicit) social norms overwrite explicit task instructions even in the absence of (alleged) social interaction. Observation enhances this effect. Fairness coding in the FRN was modulated by observation as a function of social anxiety, supporting the notion that altered sensitivity to equality in a social context may contribute to social avoidance in socially anxious individuals.
authors.affiliation: Institute of Medical Psychology and Systems Neuroscience, University of Münster, Von-Esmarch-Str. 52, 48149 Münster, Germany.
authors.forename: Jutta
authors.initials: J
authors.lastname: Peterburs
authors.affiliation: Institute of Medical Psychology and Systems Neuroscience, University of Münster, Von-Esmarch-Str. 52, 48149 Münster, Germany.
authors.forename: Rolf
authors.initials: R
authors.lastname: Voegler
authors.affiliation: Department of Psychology, University of Münster, Fliednerstr. 21, 48149 Münster, Germany.|Institute of Psychology, German Sport University Cologne, Am Sportpark Müngersdorf 6, 50933 Cologne, Germany.
authors.forename: Roman
authors.initials: R
authors.lastname: Liepelt
authors.affiliation: Institute of Medical Psychology and Systems Neuroscience, University of Münster, Von-Esmarch-Str. 52, 48149 Münster, Germany.
authors.forename: Anna
authors.initials: A
authors.lastname: Schulze
authors.affiliation: Institute of Medical Psychology and Systems Neuroscience, University of Münster, Von-Esmarch-Str. 52, 48149 Münster, Germany.
authors.forename: Saskia
authors.initials: S
authors.lastname: Wilhelm
authors.affiliation: Department of Biological Psychology, Institute of Cognitive Neuroscience, Ruhr-University Bochum, Universitätsstraße 150, 44801 Bochum, Germany.
authors.forename: Sebastian
authors.initials: S
authors.lastname: Ocklenburg
authors.affiliation: Institute of Medical Psychology and Systems Neuroscience, University of Münster, Von-Esmarch-Str. 52, 48149 Münster, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Straube
mesh_terms: D000293:Adolescent; D000328:Adult; D001007:Anxiety; D005260:Female; D006801:Humans; D008297:Male; D011340:Problem Solving; D012919:Social Behavior