Reading is an extremely complex activity involving many different brain functions.
In order to read a text fluently, the eyes must adhere to a sequence of resting phases and gaze jumps precisely controlled by the brain. During rest periods, the eyes are fixed on a place (the fixation point) within a word. Here, what we want to read is fixed. The choice of the location of the fixation point has physiological reasons: Only in the area of the fixation point is there a sufficiently high visual acuity to see letters of a normal print or handwriting sufficiently clearly. Since this area of highest visual acuity on the retina only has a diameter of about 1.5 mm, what one wants to see must lie in the area of sufficiently high visual acuity. The exact position of this fixation point depends on how many letters the word or word segment to be read contains. For normal readers, the fixation point is slightly to the left of the center of the word segment or word to be read.
Holistic capture of a word (segment)
During the fixation phase, the word segment/word to be read is not captured letter by letter, but holistically. Similar to how we do not recognize a face by looking at the nose, mouth, eyes and ears one after the other, then putting them together to form a face and only then judging which person it is, but seeing and recognizing it as a whole, we also see and recognize a word/word segment as a whole.
Individual segment sizes
In each fixation phase it must be decided how large the word segment to be read may be. This, in turn, depends on the reader’s ability to recognize letter combinations holistically, as there are considerable differences. It is not sufficient to see the graphic form of a word segment exactly and to recognize the letters occurring in it in all details. In order to read a word, the word segment/word must be associated with a sequence of sounds. We must be able to store sounds and sound sequences belonging to letters and letter combinations in our memory and, at the moment of reading, to retrieve what is stored in our memory quickly and without error. In addition, the meaning of words and sentences must also be retrieved or recognized from memory.
The gaze jump
Each fixation phase is ended by a leap of vision. Within each fixation phase it is therefore not only necessary to determine how long the fixation must be maintained in order to correctly recognize the word segment/word to be read. The size of the impending eye jump and the place to which the eyes should jump must also be determined correctly. During the jump, the eyes glide at high speed over word segments. In order to avoid a blurred, moving image during the eye jump, the visual performance must be suppressed during the eye jump. Once the new eye target has been reached, they must recover sufficiently quickly for the new word segment/word to be read. Fluent reading thus consists of a sequence of fixation phases and gaze jumps during which visual performances are continuously switched on and off.
Literature and training
The book on the subject: „Legasthenie und andere Lesestörungen – wie man sie erkennt und behandelt“ (Dyslexia and other reading disorders – how to recognize and treat them – German) by Prof. Dr. Dr. Reinhard Werth (clinical neuropsychologist from the LMU Munich). Current lectures and advanced training can be found under training courses and lectures.