Abstract
The topography of EEG alpha-band power (8 – 12 Hz) tracks locations held in visual working memory in a time-resolved fashion (Foster et al. 2016). However, there has been little work linking changes in the quality of alpha-band representations with changes in behavioral precision. In two experiments, we tracked changes in behavioral precision and EEG alpha-band representations as memoranda were repeated across trials. In Experiment 1 (n = 16), participants performed a 1-item spatial working memory task. During each trial, participants remembered a briefly presented spatial location (100 ms) over a blank delay (1,000 ms) and reported the remembered location using a mouse click. The same memory display was repeated six trials in a row. In Experiment 2 (n = 23), participants performed a 1- or 2-item spatial working memory task, and each display repeated three times. In both experiments, behavioral precision improved for repeated displays relative to novel displays, and the quality of alpha-band representations likewise improved. Previously, it has been demonstrated that alpha-band representations track memory content independent from response preparation; thus, the observed changes in the quality of alpha-band representations rule out simple motor priming accounts of improvement across repetitions. These data also demonstrate that decoded alpha-band representations are sensitive to subtle improvements in the quality of working memory representations (here, an average response error improvement of only around 1 degree). Finally, we observed that participants continued to attend to the previously remembered location (as measured by the presence of alpha-band representations) during the inter-trial interval, suggesting that the behavioral boost for repeated stimuli came from covertly attending relevant locations at the time of encoding.
Meeting abstract presented at VSS 2017