Object-based encoding constrains storage in visual working memory

• Published in: Journal of experimental psychology. General Vol. 153; no. 1; p. 86
• Main Authors: Ngiam, William X Q, Loetscher, Krystian B, Awh, Edward
• Format: Journal Article
• Language: English
• Published: United States 01.01.2024
• Subjects: Attention - physiology; Humans; Memory, Short-Term - physiology; Mental Recall - physiology; Visual Perception - physiology
• ISSN: 1939-2222
• DOI: 10.1037/xge0001479

The fundamental unit of visual working memory (WM) has been debated for decades. WM could be object-based, such that capacity is set by the number of individuated objects, or feature-based, such that capacity is determined by the total number of feature values stored. The present work examined whether object- or feature-based models would best explain how multifeature objects (i.e., color/orientation or color/shape) are encoded into visual WM. If maximum capacity is limited by the number of individuated objects, then above-chance performance should be restricted to the same number of items as in a single-feature condition. By contrast, if the capacity is determined by independent storage resources for distinct features-without respect to the objects that contain those features-then successful storage of feature values could be distributed across a larger number of objects than when only a single feature is relevant. We conducted four experiments using a whole-report task in which subjects reported both features from every item in a six-item array. The crucial finding was that above-chance recall-for both single- and multifeatured objects-was restricted to the first three or four responses, while the later responses were best modeled as guesses. Thus, whole-report with multifeature objects reveals a distribution of recalled features that indicates an object-based limit on WM capacity. (PsycInfo Database Record (c) 2024 APA, all rights reserved).