The mirror effect is the finding that in recognition tests, a manipulation that increases the hit rate also decreases the false alarm rate. For example, low frequency words have a higher hit rate and a lower false alarm rate than high frequency words. Because the mirror effect is held to be a regularity of memory, it has had a pronounced influence on theories of recognition. We took advantage of the recent increase in the number of linguistic databases to create sets of stimuli that differed on one dimension (contextual diversity, frequency, or concreteness) but were more fully equated on other dimensions known to affect memory. Experiment 1 (contextual diversity), Experiment 3 (frequency), and Experiment 5 (concreteness) found no evidence of a mirror effect. We also conducted parallel experiments which used previously published stimuli that could not avail of the new databases and which therefore contained confounds. Experiment 2 (contextual diversity), Experiment 4 (frequency), and Experiment 6 (concreteness) all resulted in mirror effects. If this pattern of results is replicable, it has broad implications for theories of recognition, which typically view the mirror effect as a benchmark finding. Unfortunately, few articles on the mirror effect include the stimuli, rendering the past literature of little use in testing this hypothesis. We encourage researchers to create and assess other pools of highly controlled stimuli to establish whether the stimulus-based mirror effect obtains when confounds are eliminated or whether it is due to the presence of these confounds.