The authors make 3 points in response to F. Schlaghecken and M. Eimer's proposal of self-inhibition as an explanatory factor in the negative compatibility effect: (a) The self-inhibition hypothesis lacks empirical support for its main tenets; (b) considering the roles of geometric, spatial, and temporal similarity of primes and masks makes self-inhibition unnecessary; and (c) the negative compatibility effect occurs even when the main tenets of self-inhibition are violated. The authors propose that understanding what is "relevant" in a masked-priming task applies not only to geometric features that are shared with the target but to spatial and temporal ones as well. Briefly, target-mask similarity determines how motor preparation is accumulated during the prime-mask sequence.