Self-related information is under many circumstances processed in a preferred and biased way, leading to what has been termed the self-prioritisation effect (SPE). The SPE has been demonstrated with arbitrary stimuli assigned to self and others, thereby controlling the influence of familiarity, and originally been attributed to facilitated perceptual processing of self-related stimuli. Subsequent studies, however, casted doubts on this interpretation and suggested further possible sources for the SPE. In the present four experiments, we used the well-established psychological refractory period paradigm together with the locus of slack and the effect propagation logic to pinpoint the source of the SPE. The data consistently demonstrated the SPE across all experiments. More important, the results converge on the notion that the SPE has its source in a capacity-limited stage of central processing. The implications of these results are discussed in light of possible candidate processes as sources for the SPE, such as memory-related processing.