It happens as often as 16% of our conscious lives: the mind simply goes blank. There is nothing inside, no verbal thinking, no mental images, nothing but the lack itself of mental processes. Scientists are now uncovering the way these episodes, known as mind blanking, are actually a real pause within consciousness and have a surprisingly similar level of activity to what is measured during stages of deep sleep or anesthesia.
One study done at Sorbonne Université saw 62 participants perform the simple attention task with occasional probing of mental state. The participant responded based on whether they were thinking of the task or if their mind was wandering or blank or “can’t remember.” The study showed that mind blanking happened approximately half as often as mind wandering, though differently because it protracted responses with increased omission errors while not responding to cues, unlike mind wandering that sped up responses with increased impulsive False Alarms.
These contrasting processes can be accounted for, from an engineering perspective, through their neural signature. EEG and fMRI analyses indicated how, during mind blanking, there was a particular frontal-parietal dissociation and decoupling of activity of specific areas, which are responsible for visual processing, being observed. These contrasting processes were not found during mind wandering. Contrasting observations were obtained for analyses of results on connectivity. These included specific areas being synchronized, while there was also decoupling of information flow between the specific frontal and parietal areas, which form a very crucial area responsible for the aspect of consciousness. These specific strict processes occur while there is loss of consciousness in mammals and human beings.
The sequence of the process of sensory processing was also affected. Normally, the activation associated with visual stimuli happens early, with a time of about 200 milliseconds, followed by later activation stages associated with conscious processing. However, during mind blanking, the early activation associated with visual stimuli was intact, followed by the failure of the later activation stages. The classifiers based on the brain activity associated with machine learning were successful in the prediction of visually presented stimuli during the states of both attention and mind-wandering, but not during mind blanking.
The findings are consistent with other fMRI studies showing that the “empty mind” task results in the deactivation of the Broca’s area, hippo-campus, and other regions involved in language and memory. However, the findings on the deactivation of the Broca’s area have special significance inasmuch as internal speech and the metacognitive process of thought identification are fundamental to the idea and implementation of a blank mind, wherein the awareness about one’s thoughts simply stops to exist and makes the mind go blank. The spontaneous mind blanking paradigm entails the deactivation of the regions discussed earlier without activation of the fronto-medial regions and indicates an absence of proactive thought suppression.
Electrophysiologically, mind blanking is marked by reduced signal complexity on parietal electrodes, increased delta power, and entry of sleep-like slow-wave activity into wakefulness. Local events of sleep, temporarily signaling that areas of the cortex are in a sleep-like state, relate to patterns during sleep onset, sedation, and disturbances in consciousness. During disturbances in consciousness, impairment in the fronto-parietal network’s integrative function may contribute to problems in maintaining complex contents of consciousness. Moreover, improved detection techniques that rely on increasingly sophisticated analyses are continually enhancing detection power. EEG, as well as machine learning algorithms such as Support Vector Machines, provide a means to detect subtle transitions in brain states, alpha, theta, hemispheric lateralization, and Heart Rate Variability.
These techniques have been remarkably successful, by any standards, in detecting differences between states of wakefulness and engagement, and might well be utilized to detect “mind blanking episodes” on-line. Graph neural networks, inspired by models of connectivity with a particular attention to spatio-temporal dynamics, promise even more exciting detection capabilities, purely from exploiting connectivity dynamics with respect to cortical connectivity, offering dramatically enhanced capabilities with regard to model interpretability and modelability.
In a radical reconceptualization that emerges from cross-validations between behavioral findings, neuroimage findings, and computational analyses, a radical redefinition of “mind-blank” episodes from what was previously a no more than briefly distracted state to a process that might more aptly be considered to be a recognizable, particular physiological state, where “the machinery of conscious experience momentarily shuts off,” whether from states involving low arousal, or local invasions of sleep, even perhaps no more than momentary metacognitive disconnections, does seem to serve some particular functional purpose, akin to that accruing from a “mini-resetting” of the brain.
