On the role of individual items in recognition memory and metacognition: challenges for signal detection theory

The authors tested the role of individual items in recognition memory using a forced-choice paradigm with face stimuli. They constructed distractor stimuli using morphing procedures that were similar to two parent faces and then compared a studied morph against an unstudied morph that was similar to two studied parents. The similarity of the parent faces was carefully balanced so that the choosing rates for the studied and unstudied morphs were approximately equal. Despite being equally likely to choose the studied and the unstudied morph, participants were systematically more confident when choosing the studied morph. This result is incompatible with Gaussian signal detection theory, even with unequal variances for targets and distractors. The authors propose an extension of an extant sampling model, SimSample, which provides a qualitative and quantitative account of the confidence and recognition dissociation. The results suggest that observers make contact with individual items when making recognition judgments with faces and that the structure of the sampling and decision process naturally leads to this dissociation of confidence and recognition.