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Amanda E. van Lamsweerde, Jeffrey S. Johnson; Feature and object representations in visual working memory are subject to top-down control. Journal of Vision 2014;14(10):39. doi: 10.1167/14.10.39.
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© ARVO (1962-2015); The Authors (2016-present)
Visual working memory (VWM) has a capacity limit of about 3-4 items; this limit is generally thought to operate on the level of an object (Luck & Vogel, 1997). However, it is also possible to group across objects of similar color (Peterson & Berryhill, 2013). We examined whether use of object and feature-grouping representations is constrained by top-down control. Participants viewed colored shapes and detected changes to: color-only, shape-only, or color-or-shape (either). Within a display, all of the features were unique (e.g., never two blue objects) or some of the features would be repeated. Detecting a single change type made the non-changing feature task-irrelevant, encouraging feature-grouping representations. However, detecting either change type should encourage participants to remember all of the features of an object, facilitating object-based representations. When detecting single change type (color-only or shape-only), performance was better when features were repeated than when they were unique. This indicates that identical colors and shapes can be grouped together in VWM. In addition, for both unique and repeated displays, performance was better at set size 3 than set size 4 (a typical set size effect); however, for color changes, performance for set size 4 - repeated features was equal to performance for set size 3 - unique features. Grouping by color may be so robust that adding an additional object to the 'grouped' representation incurs no additional cost to VWM capacity. However, when detecting either type of change within a block, there was no repetition advantage. Therefore, remembering both features of an object encouraged participants to remember features within an object together, rather than grouping features across objects. Therefore, not only can visual information be represented both as objects and feature groupings, but the use of each strategy can be modulated by top-down control.
Meeting abstract presented at VSS 2014
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