Retrieval-induced forgetting (RIF) occurs when retrieving items from memory impairs subsequent recall of related but not retrieved items. Theoretical debate exists regarding the mechanisms of RIF in terms of inhibition versus interference, which may stem from the fact that previous studies on individual differences in RIF have neglected the correlated costs and benefits (CCB) problem. To investigate whether RIF in undergraduate students with different levels of cognitive inhibition was affected by CCB, this study considered item competitive intensity. Participants retrieved low-intensity items under strong-item competitive intensity and the reverse under weak-item competitive intensity. The results showed that participants with low cognitive inhibition exhibited no RIF at both strong- and weak-item competitive intensities, while those with high cognitive inhibition only exhibited RIF at the strong-item competitive intensity. Competitive intensity is effective for testing and discriminating the confounding effects of RIF by CCB. It can be posited that, regardless of the cognitive inhibition levels of undergraduate students, inhibition is the mechanism of RIF and is not affected by CCB.