Aims: Social cognition hinges on the fundamental capability to perceive the presence of others. Research indicates that the mere presence of conspecifics can enhance task performance, particularly in simpler tasks, and is closely associated with the activity of context-dependent neural subpopulations. While attentional modulation (attentional-conflict theory) has long been posited as the primary mechanism driving social facilitation, the literature on the neurobiological underpinnings of this modulation remains scant at best. Understanding these mechanisms could yield critical insights into social perception and its disruptions in neuro-pathologies such as Autism-Spectrum Disorder and Schizophrenia. We propose that the observed improvements in performance during conspecific presence largely stem from variations in effective brain connectivity. Methods: To investigate this hypothesis, we employ a Bayesian Learning framework across multiple scales and two primate species (Rhesus monkeys and Human participants). Utilizing Hamiltonian Monte-Carlo and Simulation-Based Inference, we derive posterior distributions of effective connectivity during both the absence and presence of conspecifics across three scales: Micro-scale (single neurons), Meso-scale (Event-Related Potentials/ERPs), and Macro-scale (Whole-brain EEG). Results: Our analysis reveals a consistent increase in effective connectivity across all three scales during conspecific presence. Furthermore, subjects experiencing facilitated performance in the presence of conspecifics exhibit a strong correlation between effective connectivity and task performance within networks implicated in attentional modulation, such as the dorsal attention network (DAN) and ventral attention network (VAN). Conclusion: These findings provide compelling evidence in support of the attentional-conflict theory of social facilitation.