Benjamin Maier investigates the thinking about ourselves, which takes place precisely when we are not perceiving, reasoning or making decisions.

Viewed from a purely neuro-scientific perspective, it appears that the ego, which is associated with the sense of self, makes up the most important part of all our mental operations. In some ways, we even think about ourselves when we do not think.

In general, all cognitive processes − mental operations such as perceiving, reasoning, memorizing, or learning − occur at two stages. There is an active stage, in which the brain is processing sensory information, and a passive stage, during which no external stimuli act on the brain. In the former stage, the sensory information from environmental stimuli is transformed (or “transduced”, in technical language) into neurochemical signals, which are then processed in the brain to enable us to perceive the world around us. For example, if we see a red car driving by in front of us, various sequential mental operations lead to our final perception, and hence interpretation, of the red car. First, the stimulus, in this case visual input (the red car), sends out information to our sense organs in the form of light. In this case the radiated light travels in form of wavelengths, which are absorbed by our eyes. More specifically, the wavelengths pass through the lens and fovea of both eyes, and then are processed by specific cells named “photoreceptors” (rods, cones, and ganglion cells) located at the very rear of the eye. These photoreceptors convert the light in form of wavelengths into other types of energy, such as action potentials. Action potentials are the means by which energy or signals can travel electrically along a single neuron. On the microscopic level, neurons are independent, distinctive cells which make up the major material or substance our brain consists of. Once an action potential has reached the end part of a neuron, the signal is passed on to adjacent (termed “afferent”) neurons by a chemical process. In this way, the neurons can communicate sensory information to specific parts of the brain. In our case, the information processed by the photoreceptors is passed on to the visual cortex. The visual cortex serves as the primary relay station for visual input, and transmits information further to two primary pathways, called the dorsal and ventral stream. These streams then interpret the object in terms of its shape (“what”) and its location or moving direction (“where”).

In a brief summary, the visual stimulus sending out wavelengths is captured by the relevant sense organ (process of sensation) and next transformed into another form of energy (process of transduction), which is then processed in other distinct areas of the brain so that we can perceive or interpret the stimulus in terms of its shape and location (process of perception). Hence, perception is a higher brain function which enables us to interpret events and objects in the world.

In the active stage of the brain, not only visual information is processed, but also all other stimulus input found in our environment, such as auditory or somatosensory information. As already mentioned, higher mental operations are performed as well during the active stage, including processes commonly referred to as “thinking”, such as reasoning and making decisions.

There are obviously plenty of stimuli which require our attention and are hence to be processed by our brains. In order to be able to deal with this enormous amount of information, the brain also needs so-called “resting stages.” These resting stages are marked by a lack of external stimuli acting on us. In other words, for a limited time we are not focused on the outside world and thereby allow the brain to be in a wakeful rest. Neuroscientists recently discovered that certain brain regions – including part of the medial temporal lobe (which plays a key role in the formation of long-term memory), part of the medial prefrontal cortex, and the posterior cingulate cortex – are active during these non-processing resting stages. They refer to these regions as the “Default Network”, because it was found that certain interconnected areas of the brain are deactivated during goal-oriented activities, such as performing calculations or solving complex tasks. However, the Default Network appears to be responsible for task-independent introspection, or self-referential thought. Put differently, whenever an individual engages in thoughts associated with him or herself, this particular network of brain regions is activated. Scientists suggest that the Default Network may be required for generating spontaneous thoughts during mind-wandering, and that it may be an essential component for creativity. More specifically, it becomes active when individuals focus on internal tasks, such as daydreaming or envisioning the future.

Subsequent studies revealed that the Default Network is not only activated when individuals refrain from conscious, goal-oriented thinking, but also when they are sleeping or are comatose. Interestingly, these mind-states have in common that they lack the presence of external stimuli, and therefore free the brain from the usual task of processing information about the surrounding environment. Derived from this observation, Dr. Pierre Magistretti, a scholar at the Brain-Mind-Institute of Lausanne, concluded that the activation of the Default Network represents an introspective activity of the brain, during which the center of our consciousness or awareness is reflecting about itself.   

Furthermore, various studies support the hypothesis of a Default Network that is correlated with self-awareness. For instance, research results indicate that in children up to twelve years, the Default Network is significantly less developed (or less often activated). Similarly, patients suffering from Alzheimer‘s disease also have a less active Default Network compared to healthy individuals. Considering that both groups exhibit a far less distinct tendency towards self-awareness than normal adults do, these findings are of high interest. 

In conclusion, extensive research provides good reason to associate certain regions of our brains with self-awareness. Also, it appears to be likely that a specific network, responsible for these self-directed thoughts, is at work when we do not engage in goal-oriented thinking, and when our brain is not occupied with processing external stimuli. However, it must be mentioned that these recent findings are controversial among scholars, and that many subsequent and more sophisticated studies are required until a definite conclusion can be drawn. Nonetheless, with regard to current research, we already grasp the important role self-referential thought is playing in the neurosciences, and we also begin to understand what the paradoxical phrase “we even think about ourselves when we do not think” really means.