Implicit attention to negative social, in contrast to nonsocial, words in the Stroop task differs between individuals high and low in loneliness: Evidence from event-related brain microstates

Being on the social perimeter is not only sad, it is dangerous. Our evolutionary model of the effects of perceived social isolation (loneliness) on the brain as well as a growing body of behavioral research suggests that loneliness promotes short-term self-preservation, including an increased implicit vigilance for social, in contrast to nonsocial, threats. However, this hypothesis has not been tested previously in a neuroimaging study. We therefore used high density EEG and a social Stroop interference task to test the hypothesis that implicit attention to negative social, in contrast to nonsocial, Words in the Stroop task differs between individuals high versus low in loneliness and to investigate the brain dynamics of implicit processing for negative social (vs nonsocial) stimuli in lonely individuals, compared to nonlonely individuals (N = 70). The present study provides the first evidence that negative social stimuli are differentiated from negative nonsocial stimuli more quickly in the lonely than nonlonely brains. Given the timing of this differentiation in the brain and the fact that participants were performing a Stroop task, these results also suggest that these differences reflect implicit rather than explicit attentional differences between lonely and nonlonely individuals. Source estimates were performed for purposes of hypothesis generation regarding underlying neural mechanisms, and the results implicated the neural circuits reminiscent of orienting and executive control aspects of attention as contributing to these differences. Together, the results are in accord with the evolutionary model of loneliness.