Preparing for the future during ongoing activities is an essential skill. Yet, it is currently unclear to what extent we can prepare for the future in parallel with another task. In two experiments, we investigated how characteristics of a present task influenced whether and when participants prepared for the future, as well as its usefulness. We focused on the influence of concurrent working memory load, assuming that working memory would interfere most strongly with preparation. In both experiments, participants performed a novel sequential dual-task paradigm, in which they could voluntary prepare for a second task while performing a first task. We identified task preparation by means of eye tracking, through detecting when participants switched their gaze from the first to the second task. The results showed that participants prepared productively, as evidenced by faster RTs on the second task, with only a small cost to the present task. The probability of preparation and its productiveness decreased with general increases in present task difficulty. In contrast to our prediction, we found some but no consistent support for influence of concurrent working memory load on preparation. Only for concurrent high working memory load (i.e., two items in memory), we observed strong interference with preparation. We conclude that preparation is affected by present task difficulty, potentially due to decreased opportunities for preparation and changes in multitasking strategy. Furthermore, the interference from holding two items may reflect that concurrent preparation is compromised when working memory integration is required by both processes.
