This paper reviews studies on the cardiac pre-ejection period (PEP) in the field of cognitive psychophysiology. The main objective was to better understand the relationship between PEP and effort mobilization in cognitive functioning. We reported studies that have measured the PEP in various cognitive tasks and experimental paradigms and other additional works that have highlighted inter-individual variability affecting PEP during both resting and cognitive activities. The reported literature tends to confirm that PEP might be a useful tool to measure cardiac sympathetic control related to effort mobilization and task difficulty. Methodological aspects, influencing factors (importance of success, emotions, psychiatric condition…), and limitations of the PEP usefulness (e.g., high inter-individual variability, questionable relevance in within-subject design) are also emphasized. Finally, we raised some questions and offered directions for future research to further our understanding of PEP measures.