The affective and cognitive mechanisms elicited by the experience of social exclusion—or ostracism—have recently been explored using behavioral and neurocognitive methods. Most of the studies took advantage of the Cyberball paradigm, a virtual ball tossing game with presumed co-players connected via the internet. Consistent behavioral findings indicate that exclusion obviously threatens fundamental social needs (belonging, self-esteem, meaningful existence, and control) and lowers mood. In this study, we followed the question whether the credibility of the setting affects the processing of social exclusion. In contrast to a control group (standard Cyberball setup), co-players were physically present in an experimental group. Although the credibility of the virtual ball tossing game was significantly enhanced in the experimental group, self-reported negative mood and need threat were not enhanced compared to the control group. Event-related brain potentials (ERPs), however, indicated a differential processing of social exclusion. The N2 amplitude triggered by occasional ball receptions was significantly reduced in the experimental group. This effect was restricted for an early time range (130–210 ms), and did not extend to the following P3 components. The ERP effect in the N2 time range can be related to a differential social reward processing in ostracism if co-players are physically present. The lack of a corresponding correlate in the behavioral data indicates that some facets of ostracism processing are not covered by questionnaire data.

Previous research suggests that the established link of vertical position and self-assignment of social power affects the processing of social exclusion. We hypothesized that verticality-induced self-assignment of social power moderates the evaluation of exclusion via a change in subjective expectancy of social participation. Following this idea, a superior position-associated with higher power-was supposed to increase the sensitivity for a transition to social exclusion. The transition was simulated in a virtual ball tossing game (cyberball): an inclusionary block was followed by partial exclusion of the participant. The participants' vertical position relative to the co-players was varied in three experimental groups (superior vs. even vs. inferior). From inclusion to partial exclusion, we observed an increase of an event-related brain potential related to the violation of subjective expectancy (P3), and participants reported a corresponding increase in threat to social needs and negative mood. For participants at inferior position exclusionary effects on both, P3 and need threat, were less pronounced as compared to participants at even or superior position. These results indicate that verticality impacts basic cognitive processes of subjective expectancy formation. An inferior position already provides a bias for the loss of social power, and the transition to social exclusion is less unexpected.

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Social participation can be examined using the Cyberball paradigm, a virtual ball-tossing game. Reducing the involvement of the participant is supposed to activate a neural alarm system, and to threaten fundamental social needs. Our previous findings indicate that the latter process can be linked to an enhancement of the centro-parietal P3 amplitude, signaling a modulation of the subjective expectancy of involvement. A preceding more frontal ERP component, the P2, does not depend of the probability of involvement, but reflects the appraisal of social reward. In this experiment, we examined whether overinclusion of participants enhances the satisfaction of social needs, reduces the P3 amplitude correspondingly, and affects central reward processing. In the control condition, participants (n = 40) were included (two co-player, ball possession 33%), and overincluded (ball possession 46%) in the experimental condition. In a counterbalanced design, we also controlled for the order of conditions. As predicted, overinclusion increased the satisfaction of social needs, with exception of “self esteem”, and reduced the P3 amplitude. As for the frontal P2, overinclusion only enhanced the amplitudes if the less frequent involvement (condition: inclusion) was experienced previously. The behavioral and P3 data suggest that the feelings of social belonging, meaningful existence, and control are related to the subjective expectancy of social involvement, and can be described in terms of a linear continuum ranging from exclusion to overinclusion. In contrast, appraisal of social rewards does not depend on the probability of involvement.

Changes in functional connectivity of cortical networks have been observed in resting-state EEG studies in healthy aging as well as preclinical and clinical stages of AD. Little information, however, exists on associations between EEG connectivity and cortical amyloid load in people with subjective memory complaints. Here, we determined the association of global cortical amyloid load, as measured by florbetapir-PET, with functional connectivity based on the phase-lag index of resting state EEG data for alpha and beta frequency bands in 318 cognitively normal individuals aged 70–85 years with subjective memory complaints from the INSIGHT-preAD cohort. Within the entire group we did not find any significant associations between global amyloid load and phase-lag index in any frequency band. Assessing exclusively the subgroup of amyloid-positive participants, we found enhancement of functional connectivity with higher global amyloid load in the alpha and a reduction in the beta frequency bands. In the amyloid-negative participants, higher amyloid load was associated with lower connectivity in the low alpha band. However, these correlations failed to reach significance after controlling for multiple comparisons. The absence of a strong amyloid effect on functional connectivity may represent a selection effect, where individuals remain in the cognitively normal group only if amyloid accumulation does not impair cortical functional connectivity.