Social motivation is a powerful drive that causes us to preferentially orient towards stimuli with social value, to find social interactions rewarding, andto develop behaviors to maintain a social network. This motivation is present from early in life: infants prefer human speech to noise1, 2 and prefer direct gaze to someone looking away3-6. As adults, we find smiles rewarding and the same neural structures that respond to other types of rewards like food and money, respond to smiles7. Social interest can be so rewarding that deprivation can lead to a state that resembles physical pain8, 9. In fact, chronic loneliness is a larger mortality risk than smoking cigarettes, being obese, or being an alcoholic10-14. One hypothesis posits that a chronic impairment in social motivation underlies the social deficits in autism15. Despite the strong role social motivation plays in our everyday lives and the substantial part this may play in health problems and autism, little is known about social motivation in the typical population. In addition, there are no neuroimaging studies that examine the impact of altered social motivation on attention processes. Here, we outline the beginning of a protocol to examine social motivation in the normal population, using paradigms previously used in studies of food motivation and goal-directed attentional search. Experiment 1 (Aim # 1) will test the hypothesis that social motivation varies in the population and that the impact of altered social homeostasis (via an ostracism paradigm) will affect attention systems in the brain. Adults will answer questionnaires to assess trait-levels of social motivation16. Participants will then play the cyberball game, in either an inclusion or an ostracism condition. This will be followed by a covert-orienting task, with social and non-social targets. I predict that following ostracism, participants'responses will be faster for social cues compared to non-social cues, and that this will differ by group membership (ostracism vs. inclusion). Furthermore, I predict that this enhanced response will correlate with individual differences in social motivation. Experiment 2 (Aim #1) will test whether enhanced processing of social cues is associated with increased activation in retinotopically defined intraparietal sulcus (IPS), a region important for spatial attention. I predict that social cues will evoke a stronger response in the IPS for participants in the ostracism group compared to the inclusion group. Experiment 3 (Aim #2) will test whether object-based attention is altered in response to social ostracism. Participants will complete a category localizer to define patterns in object-selective cortex (OSC) that are associated with (1) cars and (2) people. Following, they will look at photographs of scenes that contain either people (but no cars) or cars (but no people) while performing a repetition detection task in two separate sessions: one following ostracism and one following inclusion. I predict that the correlation of people patterns in OSC in the category localizer and patterns associated with scenes containing people will positively increase following ostracism compared to inclusion.
Social interaction significantly modulates both physical and mental health. Impaired social motivation may underlie autism spectrum disorders and social isolation can decrease post-stroke survival rate and increase rates of cancer growth17,18. Social isolation can also result in increased vulnerability to psychiatric disorders (e.g. depression, anxiety, schizophrenia) and susceptibility to high-risk behaviors (e.g. substance abuse) 14. Chronic loneliness is a larger mortality risk than smoking cigarettes, being obese, or being an alcoholic10-14. Research investigating how the brain responds to altered social homeostasis and how this affects basic processes like attention will provide a better foundation for understanding how chronically altered social motivation can impact mental and physical health.