In the study of verbal memory, a critical question is the extent to which recognition is influenced by the prior contexts in which items have appeared (‘context noise’), as opposed to competition from other items present within the immediate task context (‘item noise’). In a standard recognition task, subjects study a list of words, and at test, discriminate between studied items (targets) and novel items (foils). To disentangle the contributions of context and item noise, we systematically manipulated both the contexts in which critical items had been encountered prior to study, and the composition of the recognition list, varying semantic similarity among items. Our results suggest independent contributions of each factor, with word frequency and temporal lag as important mediating variables. These findings can be interpreted within both associative learning and memory paradigms

In the study of recognition memory, a mirror effect iscommonly observed for word frequency, with low frequencyitems yielding both a higher hit rate and lower false alarm ratethan high frequency items. The finding that LF itemsconsistently outperform HF items in recognition was oncetermed the “frequency paradox”, as LF items are less wellrepresented in memory. However, recognition is known to beinfluenced both by ‘context noise’—the prior contexts inwhich an item has appeared—and ‘item noise’—interferencefrom other items present within the list context. In a typicalrecognition list, HF items will suffer more interference thanLF items. To illustrate this principle, we deliberatelymanipulated both the contexts in which critical items hadbeen encountered prior to study, and the confusability oftargets and distractors. Our results suggest that when noisesources are balanced, the mirror effect disappears.