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Johannes Fahrenfort, Jonathan van Leeuwen, Joshua Foster, Edward Awh, Chris Olivers; Alpha-band and raw EEG reflect distinct maintenance mechanisms during working memory. Journal of Vision 2016;16(12):711. doi: 10.1167/16.12.711.
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© 2017 Association for Research in Vision and Ophthalmology.
Recent work has shown the ability to decode working memory contents from EEG measurements. Here we investigate to what extent the type of representation underlying this decoding ability changes for different types of tasks. We employed two working memory tasks with identical items, but different task requirements. The memoranda always consisted of oriented bars. At test time however, participants either had to reproduce the correct orientation by clicking on a location in space (a more spatially oriented task), or they had to identify the correct orientation among competing similarly oriented bars, as in visual search (a task that we hypothesized relies more on maintaining the actual orientation). Decoding on induced time-frequency decomposed measures of the EEG revealed higher decoding accuracy within the alpha band for the task that favors spatial maintenance compared to the task that was assumed to rely more on the actual orientation (consistent with the assumed role of alpha in spatial attention and working memory). Interestingly, using decoding on the raw EEG signal, we were able to track the remembered orientation at similar levels of accuracy across both types of task. The interaction between task type and EEG measure suggests that induced alpha and raw EEG reflect partially distinct types of representation maintained for these tasks, the first related to spatial attention, while the second may represent additional orientation-related information.
Meeting abstract presented at VSS 2016
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