title: No evidence for an item limit in change detection.
abstract: Change detection is a classic paradigm that has been used for decades to argue that working memory can hold no more than a fixed number of items ("item-limit models"). Recent findings force us to consider the alternative view that working memory is limited by the precision in stimulus encoding, with mean precision decreasing with increasing set size ("continuous-resource models"). Most previous studies that used the change detection paradigm have ignored effects of limited encoding precision by using highly discriminable stimuli and only large changes. We conducted two change detection experiments (orientation and color) in which change magnitudes were drawn from a wide range, including small changes. In a rigorous comparison of five models, we found no evidence of an item limit. Instead, human change detection performance was best explained by a continuous-resource model in which encoding precision is variable across items and trials even at a given set size. This model accounts for comparison errors in a principled, probabilistic manner. Our findings sharply challenge the theoretical basis for most neural studies of working memory capacity.
authors.affiliation: Department of Neuroscience, Baylor College of Medicine, Houston, Texas, United States of America.
authors.forename: Shaiyan
authors.initials: S
authors.lastname: Keshvari
authors.forename: Ronald
authors.initials: R
authors.lastname: van den Berg
authors.forename: Wei Ji
authors.initials: WJ
authors.lastname: Ma
mesh_terms: D000328:Adult; D001499:Bayes Theorem; D019295:Computational Biology / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D008570:Memory, Short-Term / Q000502:physiology*; D008959:Models, Neurological; D010775:Photic Stimulation; D015203:Reproducibility of Results; D013647:Task Performance and Analysis