Quality trumps quantity at reducing memory errors: Implications for retrieval monitoring and mirror effects

Memories have qualitative properties (e.g., the different kinds of features or details that can be retrieved) and quantitative properties (e.g., the frequency and/or strength of retrieval). Here we investigated the relative contribution of these two properties to the retrieval monitoring process. Participants studied a list of words, and memory for these words was enhanced either by studying an associated picture or by word repetition. Subsequent memory tests required participants to selectively monitor retrieval for these different kinds of stimuli. Compared to words that were studied only once, test words associated with either pictures or repetitions were more likely to be correctly recognized, but critically, false recognition was reduced only when monitoring memory for picture recollections. Subjective judgments and speeded tests indicated that study repetition increased the number of test words that elicited recollection and familiarity (a quantitative difference), but studying pictures maximized the recollection of unique or distinctive details (a qualitative difference). These results indicate that memory quality is more critical than quantity for retrieval monitoring accuracy.

► Memories have both qualitative and quantitative properties.
► We investigated the effects of these properties using a retrieval monitoring task.
► We found that qualitative properties, but not quantitative ones, affected false recognition errors.
► Qualitative properties trump quantitative properties in retrieval monitoring.