Overview of experiment, analysis, and hypotheses. A, Visual description of the whole-report visual working memory task (adapted from Adam et al., 2018). A cue indicated whether participants were required to attend to the left or right side of the screen. Both sides contained the same number of colored squares but in different locations. In Experiment 1, set size was manipulated to consist of one, three, or six items on each side. In Experiment 2, the set size was kept constant at six items. After a 1,300 ms retention period, participants were prompted to indicate the color of each item of the attended side. There were nine discrete colors to choose from. B, Spectral parameterization method. From a power spectrum, the aperiodic components, the exponent and offset, were quantified separately from the periodic components, aperiodic-adjusted power. Total band power was captured as the average power within the frequency band of interest. C, Three scenarios illustrating how task-induced changes in the power spectrum appear as theta total band power changes. The theta frequency range (4–7 Hz) is highlighted in red. Scenario 1 (left) shows the assumed model whereby task-related changes in theta band activity are driven by changes in narrowband, oscillatory theta activity manifesting above a stable aperiodic signal. Scenarios 2 (middle) and 3 (right) describe situations in which a reduction in total theta power on the task (green line) from baseline (orange line) is observed, all driven by changes in aperiodic dynamics whether detectable theta oscillations are present or not.