Manipulation checks are often advisable in experimental studies, yet they rarely appear in practice. This lack of usage may stem from fears of distorting treatment effects and uncertainty regarding which type to use (e.g., instructional manipulation checks IMCs or assessments of whether stimuli alter a latent independent variable of interest). Here, we first categorize the main variants and argue that factual manipulation checks (FMCs)—that is, objective questions about key elements of the experiment—can identify individual-level attentiveness to experimental information andy as a consequence, better enable researchers to diagnose experimental findings. We then find, through four replication studies, little evidence that FMC placement affects treatment effects, and that placing FMCs immediately post-outcome does not attenuate FMC passage rates. Additionally, FMC and IMC passage rates are only weakly related, suggesting that each technique identifies different sets of attentive subjects. Thus, unlike other methods, FMCs can confirm attentiveness to experimental protocols.