Across two experiments, we tested the hypotheses that the frequency of IAMs (involuntary autobiographical memories) and IFTs (involuntary future thoughts) may be reduced due to (1) the limited working memory capacity that enables the processing of only a finite number of thoughts and/or (2) the reduced likelihood of noticing incidental, task-irrelevant cues that may potentially trigger IAMs and IFTs. To this end, participants completed a laboratory vigilance task with irrelevant cue-words to trigger IAMs and IFTs, and random thought-probes to measure their frequency. Study 1 (240 participants) manipulated the level of working memory load (none, low, high) while participants performed a letter version of the N-back. The presentation of working memory task-items and incidental cue-words in the vigilance task was also manipulated (simultaneous vs. sequential). Study 2 (240 participants) further manipulated the type of working memory load by using either verbal or visuo-spatial N-back task. In both studies, to further examine levels of incidental cue-noticing, participants also completed an unexpected cue-recognition task after completing the vigilance task.