Fig. 1: External and internal attention switching paradigm.

The paradigm consisted of two successive tasks: a A visual search task requiring externally oriented attention. The subjects were asked to find the letter T among many Ls and respond with a gamepad button press (BP) to indicate whether the T was in the upper or lower half of the square. b A self-episodic memory retrieval task requiring internally oriented attention, in which the subjects were asked to answer (using the gamepad) yes/no based on whether they agreed (or not) with a statement regarding events from their recent past. From the task sequence c, we extracted the switch trials (black frames): either external-to-internal (attention oriented first externally and then internally) or internal-to-external (vice versa). Note that the next task began immediately after the completion of the previous one, i.e., right after the button press (BP, trial time t = 0 s).