A well-established phenomenon in the memory literature is the picture superiority effect-the finding that, all else being equal, memory is better for pictures than for words (Paivio & Csapo, 1973). Theorists have attributed pictures' mnemonic advantage to dual coding (Paivio, 1971), conceptual distinctiveness (Hamilton & Geraci, 2006), and physical distinctiveness (Mintzer & Snodgrass, 1999). Here, we present a novel test of the physical-distinctiveness account of picture superiority: If the greater physical variability of pictures relative to words is responsible for their mnemonic benefit, then increasing the distinctiveness of words and/or reducing the physical variability of pictures should reduce or eliminate the picture superiority effect. In the present experiments we increased word distinctiveness by varying font style, font size, color, and capitalization. Additionally, in Experiment 3 we reduced the distinctiveness of pictures by presenting black-and-white pictures with similar orientations. In Experiment 4, a forced choice procedure was used in which subjects were asked to identify the form that each probe had taken during the study phase. The results were consistent with the distinctiveness prediction and, notably, were inconsistent with dual coding.

No abstract

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.

No abstract