Abstract
Spontaneous thoughts can arise from past memories, future tasks, and environmental cues. We developed a paradigm to investigate the stream of consciousness leading to spontaneous thoughts. While performing a concentration exercise (9 min) requiring one to focus only on one’s breathing, subjects observed spontaneous thoughts and counted the number of cognitions/percepts (‘links’) that they believed led to each spontaneous thought. In Studies 1–3, subjects reported less than 2 links per thought, over 80% of thoughts were attributed to a known cause, and roughly half of the thoughts were attributed to something outside the current environment. In Study 4, we examined the neural correlates of spontaneous thoughts triggered by external stimuli or internal, stimulus-independent factors (e.g., memories). Continuous EEG was recorded from seven active electrode sites (Fz, Cz, Pz, F3, F4, P3, and P4) as subjects indicated experiencing a thought. Subjects indicated whether their thoughts arose from internal (e.g., memories) or external (sights, sounds, smells, and bodily sensations) factors. To examine the neural correlates of each individually-reported thought, EEG was examined in short time scales (< 1 s) preceding each button press. Increased alpha correlation was observed for internal thoughts compared to a baseline condition (eyes-opened resting). In addition, increased alpha correlation in the parietal region was observed for internal compared to external thoughts. These findings are in line with previous research implicating distinct brain networks for internal and external awareness. We discuss the implications and potential future applications of this new approach for investigating the stream of consciousness.
Highlights
There is an amusing anecdote in the annals of psychology of a troubled young man asking Sigmund Freud about the meaning of a strange and recurring thought
Mind wandering and undirected thought processes are ubiquitous in human cognition, with reports indicating that individuals spend approximately 30% of the day in these mental states [73]
A large amount of research has typically examined these processes from the perspective that they are decoupled from the external environment, it is clear that spontaneous thoughts can arise from both stimulus-independent cognitions and stimuli in the environment [39,60] and likely involve dynamic interactions of memory and attention processes
Summary
There is an amusing anecdote in the annals of psychology of a troubled young man asking Sigmund Freud about the meaning of a strange and recurring thought. The young man told Freud that the same random thought kept entering his mind, even when the thought was unrelated to the current environment. The anecdote ends with Freud explaining to the young man how the recurrent thought resulted from a chain of thoughts triggered by a troubling situation, namely, that the young man had become an unexpectant father [2]. In this case, the recurring thought seemed unrelated to the current environment
Sign-in/Register to view highlights & summary 
Published Version
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call