“…To provide a conceptual definition that encapsulates research on spontaneous future cognition so far, we use the most parsimonious and consensual account of spontaneous thought, defining the spontaneous component of future thought as unintended thought that comes to mind with little effort and little control over its content (see Fox & Christoff, 2018b;Klinger, 2009). At this early stage, we see it appropriate to leave open the relevance of other aspects such as task-relatedness (i.e., task-related versus task-unrelated thought), stimulus-relatedness (stimulus-independent versus stimulus-dependent), and cuing (i.e., internal versus external, see Klinger et al, 2018), as we believe that these factors may offer independent insights into the phenomenon (e.g., the extent to which external stimuli cues internal trains of thought that appear spontaneous), but are not yet central to our current working conceptualisation (in fact, they could be orthogonal to the spontaneous nature of future thought, in that whether a thought is cued internally or externally is independent of whether it is experienced as spontaneous) (see also Berntsen, 2019, for further discussion). Ultimately, we associate spontaneous mental processes with what has been termed System 1 processes, which stand in contrast to deliberate mental processes (termed System 2 processes, associated with high effort, and slow, analytic processes, such as planning one's weekly groceries or calculating 25 × 12.…”