What is the most influential word of all?

Language makes people

The ability to generate and understand language makes people unique. But not only humans, monkeys and dogs can learn words too. So where is it, the crucial difference to our human language? And how is this medium actually developing, in which we speak and write, think and write?

By Angela Friederici, Michael Skeide and Verena Müller

Language is what defines a person. Some would reply at this point that other living beings also communicate with one another. Right. In fact, the different species can exchange information with one another in a variety of ways. You can even learn individual symbols or words as labels for different things and objects. Dogs and great apes in particular show impressive skills here. What they learn, however, is an association between a certain abstract symbol or an acoustic word form and an object, for example the term “car” and a real car. So you appropriate each “word” individually through associations.

So learning words is not what defines human language. What is it then? It is the gift of combining words according to certain rules. Because loosely strung together words do not result in a language. Only when they are joined together according to a set of rules do they have a meaning. Great apes, on the other hand, are unable to learn grammatical rules that correspond to those of a language.

Take, for example, a list of words. Sleeping, green, colorless, angry, idea. Combined according to the rules of German grammar, we might get the sentence "Colorless green ideas sleep angrily". This sentence is grammatically correct and can be processed because it follows the rules of language. However, it doesn't make sense. Because it is not only important in which order we string the words together. It is also crucial how we interpret this. The sentence structure, the syntax, is only one aspect of the language. The meaning of the individual words, the semantics, is just as important. With a few small changes, we can also give this sentence a meaning: "Some colorless green ideas sleep angrily in my head", for example. How everyone interprets this sentence for himself depends in turn on his individual knowledge of the meaning of words, which he has stored in his so-called mental lexicon of the brain.

From babbling to complex sentences

Despite the apparent limits given to our language by this set of rules, the abundance of possibilities to conjure up language from words is inexhaustible. As impressive as this infinity is, the path that our language system in the brain traverses in order to reach full maturity also seems long. Because as ecstatic as parents are when their little one speaks the first few words - whether "Ma-Ma" or "Pa-Pa" - it becomes clear at that moment which quantum leaps they have to master in order to later understand and interpret complex sentences to be able to. Some of these leaps are achieved in no time at all, others take many years.

Three-year-olds already have an extensive pool of vocabulary and can understand simple sentences without any problems. “The fox chases the hedgehog”, for example. However, the little ones reach a real hurdle when the sentence deviates from its simplest structure. For example, if you want to emphasize that it is the hedgehog and not a bird that the fox is chasing, you change the statement accordingly: "The fox chases the hedgehog". Misunderstandings are then inevitable. Because young speakers still unconsciously rely on the assumption that the subject, the hunting fox, is in front of the object, the hunted hedgehog, in the sentence. On the other hand, children already unconsciously register that the article "the" somehow does not fit the subject and does not belong at the beginning of the sentence. Only the adult brain can process the changed order of the sentence components with ease.

Why is that? Why can we on the one hand distinguish vowels from one another in the womb, but on the other hand understand grammatically more demanding sentences at the age of seven at the earliest, even if they are composed of simple words?

The brain has to mature too

In short: good things take time. The brain and its individual brain areas responsible for language mature at different speeds. Some areas only gradually consolidate their network to form other regions, so that they can then exchange information faster and more effectively.

One area that is bursting with activity from the start, even before birth, is the so-called Wernicke region in the left temporal lobe of the cerebrum, which matures very early in its development. Very early on, this brain region not only helps us to differentiate between sounds like “Ma” and “Pa” at top speeds of 0.2 to 0.5 seconds. It also decides for us whether a sequence of syllables represents a word at all and is therefore worthwhile to devote further to it. Even simple sentences consisting of a few words can already be processed here. Until around the age of three, the Wernicke region is the epicenter of our language.

It is only from this age that a second central linguistic region gradually joins: the Broca region in the forehead area of ​​our cerebrum, which is primarily dedicated to processing more complex language. It receives the pre-sorted information from the temporal lobe and gives the individually strung together words an overall meaning. Meaningful sentences are built from separate raw information. Because the neurons are wired up more and more, more complicated formulations become easier for us with increasing age.

We can therefore increasingly compensate for the increased difficulty of complex sentences by activating our Broca area more strongly than with simple sentences. But not only because of this: the connection between the two main actors in language processing, the Wernicke and Broca regions, also plays a decisive role. This bundle of nerve fibers, the arcuate fasciculus, takes a particularly long time to be fully functional. The reason: It slowly forms a thick layer of myelin around each of its fibers. This takes many years, but is then all the more effective. Similar to the plastic around the copper wire of a power cable, the myelin ensures that the electrical signals are transmitted with as few losses as possible and at high speed. The latest research has shown that the thicker the myelin layer around these high-speed cables, the faster the difficult sentences are processed. This means that more complicated formulations can only be processed just as quickly as simple formulations around the end of puberty - regardless of whether the hedgehog is the object in the first or last position in the sentence.

Watch the brain speak

We owe these findings in large part to one thing in particular: the new technical innovations of recent years, especially functional magnetic resonance imaging (fMRI). Through them we can almost watch the brain speak. By making use of the different magnetic properties of oxygen-poor and oxygen-rich blood, it shows us activated areas of the brain that are flooded with oxygen. That was a big step, because up to this point one could draw conclusions about the functioning of our thinking organ mainly using the example of patients with specific failures - and the examination of their brain after their death.

And even after these new methods have been developed, until recently they have been limited almost entirely to adult studies. Because it is crucial for meaningful recordings that the test persons do not move their head during the speech test in the tomograph. Something that is known to be particularly difficult for children. We at the Max Planck Institute for Human Cognitive and Brain Sciences have nevertheless succeeded in further developing methods that allow us - even in three-year-olds - to look into the child's brain while it is processing language. Our idea: combine the pleasant with the useful. We practice keeping still with the little ones, for example by showing them a cartoon in advance that they can watch without interruption if they keep their head still. And if the cartoon is exciting, it works.

Language development - a universal program

How universal this biological program is - from the screaming phase and the babbling phase to the acquisition of the first words and syntactic rules to the processing of complex sentence structures - is particularly marvelous in children: every child can effortlessly learn every language in the world into which it was born becomes. After the birth, it is initially open to any language, but then specializes in accordance with the respective linguistic environment. In the first few months of life, all children around the world recognize phonetic differences to the same extent, regardless of whether they are important in their respective mother tongue or not. Later they can only tell apart those who are relevant in their own mother tongue. A famous example is the difference between the speech sounds “r” and “l”, which is decisive in German to separate “Rast” from “Last”, but not in Japanese. Therefore, the Japanese lose the ability to distinguish between these speech sounds. In other languages, other sounds are irrelevant, so that they too are lost.

The medium in which we speak, read and write, think and write poetry, email and tweet, is ultimately a specifically human natural and cultural product of complexly interconnected bundles of neurons. A bundle that develops according to a given biological program, but is clearly influenced by the cultural environment in which we grow up and live. A deeper understanding of language is only possible if we consider both the scientific and the humanities aspects.

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