Involuntary memories and involuntary future thinking differently tax cognitive resources

During the past 20 years involuntary memories have been established as a noteworthy phenomenon, which occur spontaneously in everyday life and with greater frequency than expected. Other types of ideations also occur involuntarily and very frequently, both in the normal population and in clinical groups. The aim of this paper was to assess for the first time whether involuntary memories and involuntary future thoughts differ in the amount of cognitive resources, considering that both are experienced as being rather automatic. As in previous work on mind wandering, this was done by assessing the effect of different conditions on frequency of spontaneous thoughts about past and future. Involuntary memories and future thoughts were obtained in an experimental setting (vigilance task) that mimics a mind-wandering task. In it, participants saw slides (trials) with horizontal or vertical (target) lines. In half or one-fourth of the trials verbal cues were also presented. In a third condition one-fourth of the trials had verbal cues and one-fourth had simple arithmetic calculations. Participants were asked to report any mental content that crosses their mind when the vigilance task stopped. Results show that the manipulation modulates the number of both involuntary memories and future thoughts, and both engage cognitive resources. Future involuntary thoughts seem to require more cognitive effort than involuntary memories and, specifically, future scenarios require more cognitive resources than both involuntary memories and future plans. The results support previous findings showing that reporting spontaneous mental contents makes use of cognitive resources and are discussed linking the involuntary memory literature with mind wandering and metacognitive processes.