What is human consciousness made of?

Do you read these words? Then there is no doubt about the existence of your consciousness. However, what exactly consciousness is, how it is related to the brain and whether it can ever be fully explained neurobiologically remains controversial.

Scientific supervision: Prof. Dr. Georg Northoff

Published: 08/27/2013

Level: medium

  • As soon as we think about something, we do it consciously - so consciousness cannot be doubted or discussed away. Descartes summarized this insight in the famous sentence: "I think, therefore I am."
  • Awareness is what distinguishes wakefulness from a coma, for example. But it is always also consciousness of something, i.e. it relates to an object. And many more conceptual differentiations can be made, so that it is sometimes doubted whether “consciousness” actually exists as a uniform phenomenon.
  • A well-known explanatory model is the “Global Workspace Theory”, which regards consciousness as the central workspace: What happens there is available to all the diverse, largely unconscious processes in the brain.
  • For philosophy, the old “body-soul problem” crystallizes in consciousness: How are the spiritual and material worlds, which obviously function according to very different laws, connected?
  • Neuroscience is increasingly daring to tackle the topic. The extent to which consciousness can ever be explained on a purely biological and thus ultimately a physical level remains controversial.
Attention and awareness

In our everyday experience, attention and awareness are usually directed towards the same object. Nevertheless, both are not the same and also not automatically congruent. This is shown by tricky experiments on the visual system, in which different images for the left and right eye can be used to specifically manipulate what the test subjects see consciously and which image falls on their retina, but never arrives in consciousness. Regardless of this, attention can be controlled by specific instructions to the test subjects. In this way, researchers working with Masataka Watanabe from the Max Planck Institute for Biological Cybernetics in Tübingen were able to show that the activity of the primary visual cortex depends on attention, but not on whether a certain pattern is consciously seen or not (see abstract ).

The American psychologist and philosopher William James (1842–1910) characterized in his “Principles of Psychology” consciousness as something continuous that is not composed of individual parts: “It flows.” That is why he chose the river, the stream, as a metaphor for all the changeful thoughts, perceptions, emotions and feelings that occupy us, and thus coined the expression "stream of consciousness", which he saw as the "ultimate fact for psychology". The theory of the global workspace later developed from this concept.

However, there is no consensus among experts that the stream of consciousness actually exists: British researcher and writer Susan Blackmore criticizes this idea as an illusion.

Regardless of this, James ’term made a career especially in literature: The" stream of consciousness "narrative tries to depict the subjective stream of consciousness as directly as possible in writing, including wild associations and thought jumps, without periods and commas. A famous example of this can be found in James Joyce ’" Ulysses ".

There is probably no other phenomenon in the universe that we are so closely connected to as our own consciousness. Our humanity, our respective individuality as a person, our complex interaction with our environment would be unthinkable without awareness. You are currently reading this text: Do you think for yourself, do you have associations with what you have read or do you let yourself be distracted by something completely different in between? All of this happens on the stage of your very own personal consciousness.

Nothing in this world can be as certain as the fact that we are conscious the moment we think about it: “I think, therefore I am.” René Descartes built his entire philosophy on this famous foundation. Everything else we can initially doubt: All sensory impressions could be a delusion, our convictions errors, our whole environment a huge fraud - the film "Matrix" turns this consideration, which Descartes also made, into an opulent story. But awareness remains as a fact.

"One of the most puzzling characteristics of the universe"

For the contemporary American philosopher John Searle, consciousness is “the most important aspect of our life”, as he likes to explain in public lectures. His convincingly clear argument: Consciousness is a necessary prerequisite for us to be able to attach importance to things in our lives. But if without consciousness there wouldn't be anything important to us at all, nothing can be more important than consciousness itself.

As natural and common as awareness is for all of us, things get complicated on closer inspection. The neuroscientist Christof Koch, who has been researching this topic for a long time, calls consciousness "one of the most puzzling characteristics (features) of the universe". It is not for nothing that philosophers have been biting their teeth on it for centuries (the riddle of consciousness). There is still no recognized scientific definition, and even in normal use the term proves to be colorful. Neurophilosist Thomas Metzinger from the University of Mainz unfolds five different word meanings in the entry “Consciousness” in the “Encyclopedia Philosophy”.

The term can refer to whether someone is (fully) conscious or not - for example because he is sleeping (the night side of consciousness), is under general anesthesia (what happens during anesthesia?) Or is in a coma (playing tennis in Vegetative state). These states of consciousness can be defined objectively and at least partially explained neurobiologically. It becomes more difficult with the awareness that is focused on an object, another person, a fact or whatever object: If I am aware of a mistake or become aware that there is an unpleasant smell in the air, then that is yes, a highly subjective mental process. It takes place in my head alone, and other people can only hear about it if I communicate the matter - consciously or unconsciously, for example by grimacing.

Christof Koch: Do two physically identical brains have the same conscious state?

Dance on the stage of subjective experience

This awake awareness, this dance on the inner stage of subjective experience, begins in the morning when you wake up and continues uninterrupted until you fall asleep - at least it seems difficult to imagine that we are awake without a thought, a feeling, a sensory impression or an activity just consciously busy. On the other hand, this does not mean that all thoughts, feelings, sensory impressions and activities require consciousness. Rather, psychological and neurobiological research show that many such processes in our head can take place unconsciously - and thus in many cases more effectively and faster. (See also the articles If I were a zombie, How our unconscious mind decides for us, What are emotions?)

Further distinctions can be made: Awareness is not the same as attention (see box “Attention and Awareness”). Consciousness can be directed outwards, for example towards objects of perception or our own body, or it can be introspection, the perception of our own mental states. The latter case makes it clear why awareness is sometimes also described as a higher-level or metaprocess: While I am spontaneously annoyed and curse aloud at another road user, I can consciously observe and reflect on this process at the meta level - and come to the conclusion, for example that the swear phrase was rather unfavorable given the mother-in-law in the passenger seat.

From conscious reflection of a person about himself and his identity, self-consciousness and self-consciousness arise, as they have been investigated time and again by philosophers. This, in turn, has to be distinguished from self-confidence, as it is used in everyday language: the charisma of a person who is convinced of himself and his abilities.

Ned Block: For him, consciousness is like a stage in the spotlight. © Axel Cleeremans / Wikimedia Commons

The theory of the global workspace

The philosopher Ned Block from New York University also differentiates between consciousness as a phenomenal experience, i.e. our subjective experience while we look at a flower or enjoy a touch, for example, and "consciously" in the sense of "available for our thinking and behavior control" . He also calls the latter “access conscious”, and this concept is directly linked to a model of consciousness known as the global workspace theory. According to this “Global Workspace Theory”, consciousness is something like a stage in the spotlight: only what happens on the stage can be seen and heard by the audience sitting in the dark - the many unconscious processes in the brain - and therefore suits them However, from the point of view of some philosophers, the many differentiations make it questionable whether consciousness is a single, uniform phenomenon or not more of a collective term for different things. This is also indicated by the fact mentioned in Metzinger's encyclopedia article that there is no equivalent for this comprehensive term in many languages. Among other things, it could be that the awareness of natural scientists was not considered a proper research subject for a long time. There are still hundreds of pages of up-to-date neuroscience textbooks in which the term does not even appear in the index, and John Searle quotes a neuroscientist as saying: “You can do research on consciousness - but you should first have a permanent position. "

The immortal soul is a thing of the past - questions of faith remain

But even without a disreputable aftertaste it remains an extremely difficult field. In the question of consciousness the old "body-soul problem" crystallizes to a certain extent: How are the spiritual and material world connected? How much reality does the spiritual actually have from an objective point of view? The idea of ​​a soul that can exist independently of the body has probably not been represented in science since John Eccles (John Eccles - Across the Gap), who died in 1997. In addition, it can be considered proven that the physical-neural processes in the brain are a necessary prerequisite for everything spiritual.

But whether the spiritual is also sufficiently determined is a completely different question. Is consciousness ultimately just a purely biological process, like everything else that takes place in our body - particularly difficult to research because it is a subjective phenomenon, but can at least in principle be reduced to complex physical processes? For the time being, this question remains a question of faith, which the empirical scientist Christof Koch puts in a nutshell: "It is not at all clear whether two brains that are identical from a physical point of view would automatically have the same conscious state."