Poster A42, Saturday, March 25, 5:00 – 7:00 pm, Pacific Concourse
Use-dependent coding for working memory
Nicholas E. Myers1, Maryann A. P. Noonan1, Anna C. Nobre1, Mark G. Stokes1; 1University of Oxford
Theoretical models of visual working memory (WM) generally assume that information is maintained in a WM store independent of how it will be used to guide behavior during readout. For instance, results from delayed estimation, forced choice discrimination, and change detection, are often used interchangeably to make inferences about the underlying WM architecture. However, optimizing WM storage for the required mode of recall could confer advantages to behavior by allowing observers to prepare for the specific upcoming recall task. Similar task preparation benefits have been observed in cued task switching, but the issue has not been addressed in the domain of working memory. We used a precision WM task with varying response demands while recording brain activity using electroencephalography (EEG) in human observers. Readout demands were varied by alternating between blocks of delayed estimation and two-alternative forced choice change discrimination. Importantly, the two tasks were identical during encoding and maintenance: Each trial began with the sequential presentation of two oriented gratings, followed by a retrospective cue indicating which of the two items was task-relevant. We found that EEG signatures of updating in WM during encoding of the second item, and sustained oscillations during the maintenance delay, differed depending on readout demands. Our findings illustrate that WM encoding and maintenance may already reflect preparation for readout.
Topic Area: EXECUTIVE PROCESSES: Working memory