We present a new experimental technique to induce dissociations between the visibility of a masked prime and its ability to induce a priming effect in response times. In three experiments, we systematically couple an independent variable known to influence the priming effect (prime-mask SOA) with a variable expected to influence prime visibility but not priming (mask contrast). This way, we create mask-contrast functions where mask contrast either increases with SOA, decreases, or remains constant at maximum or minimum levels. We show that different mask-contrast functions can lead to qualitatively different time courses of masking without affecting the time course of priming, allowing for double dissociations (e.g., increasing priming effects under decreasing prime visibility). For the first time, we demonstrate such double dissociations for response priming by color as well as shape stimuli. We also show that the technique requires stimuli that decouple the mask's ability to mask the prime from its ability to activate the response. We conclude that mask-contrast functions can accentuate or even induce dissociations between priming and masking, opening new possibilities for studying perception without awareness.