Story at a glance
- When you are distracted or simply not thinking about the outside world, a network in the brain — the default mode network — becomes active.
- Participants of an experiment were told to think about future events while laying in an MRI machine.
- Researchers saw that two subnetworks were active with what they think are two different functions of construction and evaluation.
When you slip into a daydream, it can feel like you are lost in a different part of your mind. Thinking about the future can bring up a variety of images and feelings, some positive and some negative. What does all of this look like in your brain’s activity?
It turns out, when your mind wanders, specific parts of your brain become active. It’s called the default mode network (DMN), and it is a group of interacting brain regions that will light up on brain scans when you aren’t thinking about the outside world.
“These regions seem to be active when people aren’t asked to do anything in particular, as opposed to being asked to do something cognitively,” said neuroscientist Joseph Kable at the University of Pennsylvania in a press release.
In a paper published in the Journal of Neuroscience, Kable and collaborators explain how, in their experiments, the activity in the DMN splits into two complementary parts when participants are imagining the future. One part helps you create and predict the future event, which serves a constructive function, and the other helps you assess whether the event is positive or negative, which serves an evaluative function.
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For the experiment, 24 people were put into a functional magnetic resonance imaging (fMRI) machine. Once inside, they got one of 32 prompts, like “Imagine you’re sitting on a warm beach on a tropical island,” or “Imagine you win the lottery next year.” The researchers let them think about that for about 12 seconds, and then participants were asked to rate their scenario for vividness and valence, which is a way to measure the positiveness or negativeness.
“Vividness is the degree to which the image that comes to mind has a lot of details and how much those details subjectively pop as opposed to being vague,” Kable says. “Valence is an emotional evaluation. How positive or negative is the event? Is this something you want to have happen or not?”
The participants went through this process four times each, and the researchers looked at their brain activity from the fMRI scans. The team found that they could distinguish the two DMN subnetworks being activated in ways that corresponded to constructive and evaluative functions.
The researchers hope that this can lead to more work on making complex assessments.
“When psychologists talk about why humans have the ability to imagine the future, usually it’s so we can decide what to do, plan, make decisions,” says Kable in the press release. “But a critical function is the evaluative function; it’s not just about coming up with a possibility but also evaluating it as good or bad.”
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