Figure 1. Task Design.

Participants performed the 2-back condition of the n-back working memory task in either a control condition (Panel A) or time-based PM condition (Panel B), in counterbalanced order. The 2-back task presented a continuous sequence of words at a regular rate (1.5s) with target responses required when the current item matched that presented 2 trials back (arrow labeled “2-back”). In the control condition, at intermittent times, a non-informative clock randomly appeared (red font) with the instruction “press 3” (indicating the relevant button to press on the response box). Upon reacting to this prompt the clock would disappear. (arrow labeled “Control Prompt”). In the time-based PM condition, participants self-initiated a clock-check with the same button-press response (arrow labeled “participant clock-check”), leading to the appearance of an informative clock indicating the elapsed time since the start of the task block. They were asked to use this information to make a target response after 3 or 4 minutes. The 2-back task continued for an additional 20 seconds following the designated target time.