Dreaming, fantasizing, worrying – these are all examples of mind wandering.
One of the most exciting breakthroughs in neuroscience research in recent years is the discovery of the default brain network (DMN). It turns out that when we’re not too busy with a certain task, our brains are still intensely active. A massive cortical network, DMN is constantly being ground down, consuming significant amounts of metabolic energy.1 As evolution repeatedly teaches us, this default activation should serve a function.
We now know that the DMN is the seat of our mental wandering,2 which includes internal processes such as dreaming, fantasizing, worrying, planning, ruminating, and our inner chatter. More formally, the quest to understand the content of our mental drift has identified 3 key functions in the DMN. The first is to maintain and manage our representation of ourselves; how we see ourselves, our traits, our dispositions, and more.3 Second, DMN and mind-wandering content have been shown to relate to our understanding of others. It’s called theory of mind (ToM), our – and largely limited – attempt at being able to infer the intentions of others.4 Third, the DMN is busy with what-if simulations and building imaginary scenarios.5 Our ability to learn from our imagination is extremely useful, in multiple areas, but vastly underestimated. But let’s start at the beginning.
The knowledge we acquire is stored in our memories in the form of associations. Facts, experiences, predictions, episodes, and even emotions are attached associatively based on what we extract from the world around us. Our brains pick up on statistical regularities, such as a pizza cutter usually appears next to pizza and a bed usually has a pillow on top, and stores related items as associations. Such an associative organization is not only advantageous for memory storage, but also for memory retrieval.
Critically, associations are the building blocks of how we make predictions.6 We are constantly concerned about the future. We are creatures who aim to maximize certainty in our world and determining how and what to predict is fundamental to reducing uncertainty. Knowing that you are about to enter a kitchen or a museum immediately activates associations about what awaits you; from where to find what, how to prepare and how to advance your goals. When our machinery for demystifying the future through association-based predictions is deficient, we become anxious and depressed.7 Associations are the units of thought and the basis of certainty.
Mixing our memories and constructing new scenarios, even if imagined, is at the heart of every decision and interpretation we make. These simulated scenarios look like real experiences, except they didn’t actually happen. Nevertheless, they are as useful for planning our actions as are real experiences.
Beyond content, mind wandering can vary in style. We can browse our network of related concepts, or we can surround a close neighborhood with highly related thoughts. And these different styles are good (and bad) for different purposes. Narrow thinking can be helpful when trying to solve a problem (but it’s bad if it’s narrow due to ruminative thoughts). On the other hand, wide wandering is the vehicle of creative thinking.
Because of the striking difference between the type of mental wandering conducive to creative thinking and the narrow ruminations that are the hallmark of anxiety and depression, we set out to investigate in the laboratory a possible relationship between the extent of thought and mood.
Thinking span and creative thinking can be assessed through a simple free association paradigm. When given the word “table”, a person in a narrow mindset would respond with “chair” as the first association. But even the same individual in a broad way of thinking is more creative and their responses will be more original, so they might respond with “tree” instead. We manipulated our participants’ span of thought by presenting them with lists of words closely associated with each other (e.g.: thread–needle–sew–twine–cloth–clothing–rope–unstitch–machine–pin –coil-thread), which mimicked ruminative, or broadly expansive thinking (e.g., thread-needle-prick-nurse-doctor-drug-alcohol-beer-wine-cheese-mouse-trap), while measuring their mood before and after. Simply reading broadly associative channel listings was a huge mood lifter.8 This effect of mind wandering and thinking on mood has been demonstrated in both depressed and neurotypical individuals. After all, who doesn’t need to feel better?
And so, we could direct our mind to wander freely when we need and want to think creatively, and we’re better off looking for creative solutions when we know we’re in a good mood. mental wandering contains a list of ways to implement this new knowledge in everyday life, as well as in potential therapy. Likewise, other circumstances, such as planning a complex course of action, require a narrower style of mind wandering. Being aware of the different types of our mind wanderings can help us bring the right mind to the right occasion.
Doctor Bar is the former director of the Cognitive Neuroscience Lab at Harvard Medical School and Massachusetts General Hospital (Psychiatry), and an internationally recognized cognitive neuroscientist. He was until recently director of the Gonda Multidisciplinary Brain Research Center at Bar-Ilan University in Israel. Moshe is the author of mental wandering and more: www.moshebar.org
1. Raichle ME. The brain’s default mode network. Annu Rev Neurosci. 2015;38:433-447.
2. Mason MF, Norton MI, Van Horn JD, et al. Wandering minds: the default network and stimuli-independent thought. Science. 2007;315(5810):393-395.
3. Davey CG, Pujol J, Harrison BJ. Mapping the self into the brain’s default mode network. Neuroimaging. 2016;132:390-397.
4. Spreng RN, Grady CL. Patterns of brain activity supporting autobiographical memory, prospecting, and theory of mind, and their relationship to the default mode network. J Cogni Neurosci. 2010;22(6):1112-1123.
5. Bar M. The Proactive Brain: Using Analogies and Associations to Generate Predictions. Cogn Sci Trends. 2007;11(7):280-289.
6. Bar M, Aminoff E, Mason M, Fenske M. Units of thought. Seahorse. 2007;17(6):420-428.
7. Bar M. A cognitive neuroscience hypothesis of mood and depression. Cogn Sci Trends. 2009;13(11):456-463.
8. Mason MF, Bar M. The effect of mental progression on mood. J Exp Psychol Gen. 2012;141(2):217-221.