The extralist-feature effect: evidence against item matching in short-term recognition memory.

The authors varied the similarity between negative probes and study items in a short-term item-recognition task. Current models treat similarity as a function of the number of occurrences of the probe's features in the study set, a factor that is often confounded with the number of the probe's features occurring in the study set. Unconfounded comparisons showed that performance reflected only the latter factor, with response time a linear function of the number of probe features in the study set. The effect was obtained for both stimuli with manipulated features (colored shapes) and words. Number of presented features is a global property of the study list, but existing global models calculate familiarity by averaging across item matches and cannot readily accommodate the data. The authors proposed that the probe's features are compared with a global representation of the study set's features.