Have you ever lost all attention to what's going on around you, been lost for thoughts or grasping at memories? These are all symptoms of 'mind blanking', a common experience with a wide variety of definitions ranging from feeling drowsy to a complete absence of conscious awareness.
Now, a team of neuroscientists and philosophers from Europe and Monash University have published a paper in the journal Trends in Cognitive Sciences compiled of what we know about mind blanking, including insights from their own work observing people's brain activity.
"During wakefulness, our thoughts transition between different contents. However, there are moments that are seemingly devoid of reportable content, referred to as mind blanking," the team say.
While they say it remains unclear what these blanks represent, author Dr Jennifer Windt of Monash University's Centre for Consciousness and Contemplative Studies, says a mind blank is more likely to occur when the brain is in a high- or low-arousal state.
"Even when we are trying to focus on what we are doing, our attention frequently drifts away from ongoing tasks and the here and now," Dr Windt said.
"Moreover, when our attention lapses, we can experience a variety of mental states, such as daydreaming and freely moving thoughts, or even no thoughts at all, as in mind blanking."
Fellow author Antoine Lutz of the Lyon Neuroscience Research Center in France said, "Our aim here is to start a conversation and see how mind blanking relates to other seemingly similar experiences, such as meditation."
Coordinating author Athena Demertzi of GIGA Research at University of Liège, Belgium said, "We sought to better understand mind blanking by parsing through 80 relevant research articles — including some of our own in which we recorded participants' brain activity when they were reporting that they were 'thinking of nothing'.''
Key findings from the research include:
Mind blank frequency varies greatly between different people, but a person experiences the phenomenon about 5 to 20 per cent of the time on average.
Common experiences defined as 'mind blanking' include lapses of attention, memory issues and a cessation of inner speech, among others.
Mind blanks tend to happen toward the end of long, sustained attention tasks like exams and after sleep deprivation or intense physical exercise, but are also a typical waking state.
Children with attention deficit hyperactivity disorder (ADHD) report mind blanking more frequently than neurotypical people.
During mind blanks after sustained attention tasks, people's heart rates and pupil sizes decreased and their brains showed lower signal complexity — a state typically observed in unconscious people. During the blank, they observed disruptions in sensory processing and slow, sleep-like EEG waves. The authors describe these states in which parts of a person's brain appear asleep as "local sleep episodes".
The researchers speculate that the common factor between different forms of blanking may be related to changes in arousal levels, leading to a malfunction of key cognitive mechanisms such as memory, language or attention.
Given that blanking experiences vary so greatly — both in terms of people's subjective experiences and their neural activity — the researchers propose a framework that describes mind blanking as a dynamic group of physiologically driven experiences mediated by arousal states, or a person's state of physiological "vigilance".
Lead author Thomas Andrillon, a former Research Fellow in Psychology at Monash, now at the University of Liège, says: "We believe that the investigation of mind blanking is insightful, important and timely. Insightful because it challenges the common conception that wakefulness involves a constant stream of thoughts. Important because mind blanking highlights the interindividual differences in subjective experience.''
