Null category-length and target-lure relatedness effects in episodic recognition: a constraint on item-noise...

There are two main classes of model of interference effects in recognition memory: item-noise and context-noise. Item-noise models predict that a loss of memory discriminability will occur with an increase in the number of studied items from the same taxonomic category (category length, CL) and that forced-choice recognition performance will be higher when the target and lure are related rather than unrelated. Context-noise models, however, predict null effects for both of these manipulations. Although results from some recent experiments suggest that CL and target-lure relatedness have a trivial or no effect on memory discriminability when the related items from the same taxonomic category are "not back to back in the study list but are separated (spaced) by interleaving items from other semantic categories," these experiments have methodological limitations that were eliminated in the present experiment in which exemplars representing category lengths of 2, 8, or 14 were presented spaced apart within the same study list. Recognition was tested using a yes/no recognition test or a two-alternative forced-choice recognition test in which the target and lure were either related or unrelated. In yes/no recognition, d' decreased as CL increased, replicating prior research. However, when the slope of the z-ROC function is less than 1.0, as is typically so and was so in the present results, d' differences can arise due to criterion shifts and are not necessarily due to memory discriminability differences. When the more appropriate measure of memory discriminability, d a , was computed, CL had no effect in yes/no recognition, nor did it have an effect in forced-choice recognition, which also was not affected by target-lure relatedness. Thus, the present results are congruent with context-noise models and pose a challenge for item-noise models.