To answer that, I went to articles and textbooks on Neurobiology, neurology, and psychology. In the search I found much evidence showing that kata have a great potential in aiding a fighter based on patterns seen in fighting as well as interpreting how someone may move.
The kata, learning, and reading your opponent:
In, ‘Essence of Okinawan Karate-do’ Shoshin Nagamine describes a kata as “…a systematically organized series of defensive and offensive techniques performed in a sequence against one or more imaginary opponents…” He goes on to say that “The movements of a kata are divided into basic and intermediate…intermediate movements serve to connect basic movements…and are frequently used in pre-arranged kumite… the intermediate and basic movements combine to produce the vital power of karate.”
By looking scientifically at Kata, the mind, and how we learn, we see how they help in Kumite and in practical self-defense and understand its value in a grander way.
Found in any neurology or psychology text book we know that in 1909 Brodmann mapped the brain by determining what areas are responsible for the functions. Area 6, he determined, was involved in learning complex coordinated movements. More recently, (1992) Di Pellegrino’s article showed that a group of cells exist in this area called mirror neurons (neuron is a nerve cell) and they are activated when an action is either seen or performed. These cells learn to determine intent based on the similar actions used previously.
This mirror neuron system is vital in human learning. It is the premise of why we learn from doing. Many articles state that these neurons help us determine a person’s intent based on pre-learned movements. So as we practice kata, the learned patterns can lead us to “know” what an opponent will do next. Besides interpreting intent, these cells are needed for learning behavior. (It has also been hinted that autism may be linked damage to these cells which may explain why some cases of autism have improved with traditional karate-do).
Most new research confirmed that body movements are learned and watching learned patterns will re-enforce these movements almost as if physically doing them, as a beginner watches a more advanced person to a kata it improves it within the mind. The modern ideas of learning show that repetition of patterns is how we learn to move. Every time a pattern is repeated, the brain begins to form physical connections in the frontal lobe of the cerebrum to make this a permanent memory. The repetition is the key to learning.
The patterns practiced are stored and can be retrieved when needed either to interpret what an attacker is going to do and what we should do to counter. In essence, the attacker’s intent is gained by their previous actions based on kata we practiced.
Our brains don’t always need the entire pattern but if kata are practiced, they give the body a sense of “not thinking” about the fight. It may feel like movements just flow, this may give the feeling of no mind activity.
The above may seem to contradict the idea of each movement of a kata being “unitary” but not for our minds, they incorporate the kata as a pattern, one movement leads to another. With repetitive practice of each Kata, our brains form long-term memories adding new pathways between brain cells to increase the ability of reaching the patterns when needed. This process is sometimes referred to as “Hard-wiring” the memory as physical connection made. There is more to the learned movements of the katas. For one, it will teach the practitioner movements from what seem like unnatural positions. If one looks closely, each position of the body is a potential intermediate position such as one might find in going from standing to sitting (as in Naihanshi (Tekki) kata, a squatting position in kata). Thus kata help in practicing from positions where an attack may come in reality rather than from a ready position.
Kata also teach the student distance. With each turn or block you learn where best to be to avoid getting hit or how much ground.
One must remember that your mind uses patterns all the time and can start or finish them where and as needed. It allows your body to modify what is known for the situation. Mostly, it is important to know that the patterns are important as a “what next” it is not a “set in stone” condition.