New research shows tuning out the external world and allowing thoughts to move freely promotes relaxation and exploration.
Researchers have come up with a way to track the flow of our internal thought processes and signal whether our minds are focused, fixated or wandering.
Using an electroencephalogram (EEG) to measure brain activity while people performed mundane attention tasks, researchers identified brain signals that reveal when the mind is not focused on the task at hand or aimlessly wandering, especially after concentrating on an assignment.
Specifically, increased alpha brain waves were detected in the prefrontal cortex of more than two dozen study participants when their thoughts jumped from one topic to another, providing an electrophysiological signature for unconstrained, spontaneous thought. Alpha waves are slow brain rhythms whose frequency ranges from 9 to 14 cycles per second.
Meanwhile, weaker brain signals known as P3 were observed in the parietal cortex, further offering a neural marker for when people are not paying attention to the task at hand.
The findings suggest that tuning out our external environment and allowing our internal thoughts to move freely and creatively are a necessary function of the brain and can promote relaxation and exploration.
Moreover, EEG markers of how our thoughts flow when our brains are at rest can help researchers and clinicians detect certain patterns of thinking, even before patients are aware of where their minds are wandering.
To prepare for the study, 39 adults were taught the difference between four different categories of thinking: task-related, freely moving, deliberately constrained and automatically constrained.
Next, while wearing electrodes on their heads that measured their brain activity, they sat at a computer screen and tapped left or right arrow keys to correspond with left and right arrows appearing in random sequences on the screen.
When they finished a sequence, they were asked to rate on a scale of one to seven -- whether their thoughts during the task had been related to the task, freely moving, deliberately constrained or automatically constrained.
One example of thoughts unrelated to the task and freely moving would be if a student, instead of studying for an upcoming exam, found herself thinking about whether she had received a good grade on an assignment, then realized she had not yet prepared dinner, and then wondered if she should exercise more, and ended up reminiscing about her last vacation, Kam said.
The responses to the questions about thought processes were then divided into the four groups and matched against the recorded brain activity.
When study participants reported having thoughts that moved freely from topic to topic, they showed increased alpha wave activity in the brain's frontal cortex, a pattern linked to the generation of creative ideas. Researchers also found evidence of lesser P3 brain signals during off-task thoughts.