Fig. 4.

Four blocked experimental conditions used in the fMRI paradigm. Example trials from the four experimental conditions: (a) SWM only, (b) VWM only, (c) SWM & search, (d) VWM & search. A cue screen appeared at the beginning of each block, indicating which task to perform for the following four trials. All conditions were matched for visual and motor responses. For the working memory only trials (a, b) a target absent visual search array was presented during the retention interval (instead of just a fixation cross used in experiment 1). The colour of the fixation cross changed from white to black to remind participants NOT to search, and subjects were asked to always report target absence. For the dual-task trials (c, d), subjects were required to perform the visual search task, whilst simultaneously rehearsing information required for the working memory task