Social information impairs reward learning in depressive subjects: behavioral and 2 computational characterization 3 4 5 Abstract (max 218/250) 16 Depression is characterized by a marked decrease in social interactions and blunted sensitivity 17 to rewards. Surprisingly, despite the importance of social deficits in depression, non-social 18 aspects have been disproportionally investigated. As a consequence, the cognitive 19 mechanisms underlying atypical decision-making in social contexts in depression are poorly 20 understood. In the present study, we investigate whether deficits in reward processing interact 21 with the social context and how this interaction is affected by self-reported depression and 22 anxiety symptoms. Two cohorts of subjects (discovery and replication sample: N = 50 each) 23 took part in a task involving reward learning in a social context with different levels of social 24 information (absent, partial and complete). Behavioral analyses revealed a specific detrimental 25 effect of depressive symptoms -but not anxiety -on behavioral performance in the presence 26 of social information, i.e. when participants were informed about the choices of another player.
27Model-based analyses further characterized the computational nature of this deficit as a 28 negative audience effect, rather than a deficit in the way others' choices and rewards are 29 integrated in decision making. To conclude, our results shed light on the cognitive and 30 computational mechanisms underlying the interaction between social cognition, reward 31 learning and decision-making in depressive disorders. 32 33 Page 3 of 29 MAIN TEXT 34 35 36 37One of the core clinical symptoms of depression is anhedonia, which refers to a reduced 38 motivation to engage in daily life activities (motivational anhedonia) and a reduced enjoyment 39 of usually enjoyable activities (consummatory anhedonia) (1, 2). In principle, this clinical 40 manifestation could be explained by reduced reward sensitivity, both in terms of incentive 41 motivation and in terms of reinforcement processes (3-5). A direct prediction of this hypothesis 42 is that depressive symptoms should be associated with reduced reward sensitivity in learning 43 contexts both at the behavioral and neural level. However, while some studies do find 44 evidence that depressive symptoms in the general population and in clinical depression are 45 associated with blunted reward learning and reward-related signals in the brain (6, 7), others 46 indicate no (8, 9) or mixed effects (5). As a consequence, there is no strong consensus about 47 which components of reward processing are most predictive of depressive symptoms in both 48 the general population and clinical depression (5).
50Another striking clinical manifestation of depressed symptoms is a marked decrease in social 51 interactions. Depression is indeed associated with social risk factors, social impairments and 52 poor social functioning (10). Surprisingly, despite the importance of the socio-cognitive 53 impairments that ...