Boris Berman advice

[piazzo23]

This is an excerpt of Boris Berman´s book:

"...Should one practice slowly? I think that one should practice as fast as one's ear can acknowledge every detail and the mind can control every motion . Slow practice is intended not just to train the fingers to move faster but to teach the mind to react faster to what the ear hears. "With sufficient repetition we need less and less time to exercise ... control," wrote Sandor.2 If the ear cannot keep pace, the playing will be muddled, even if the desired speed is achieved. Many students avoid dealing with this problem by mentally switching off for a part of a virtuoso passage. It is as if they tell their fingers, "See you in the next bar," and allow the hands to finish the rest ofthe bar automatically. These mentally skipped parts are easily recognizable by the unmusical, mechanical way in which they are played. The remedy is- you guessed it-listen tirelessly to every note you play. In the chapter "Matters of Time" I discussed how perception of musical pulse affects the the understanding and performance of a composition. It plays a similarly helpful role in overcoming the technical challenges of a of a work. Suppose a student is learning Chopin's "black keys" Etude in G-flat Major, op. 1o, no. 5 (Ex . 6.15). Having studied each hand's part separately, he then combines them. Most likely, at this early stage he feels the eighth note pulse (four beats to a bar). He starts appropriately with a slow tempo, gradually increasing the speed as his mind and his fingers become more familiar with the music. He may ultimately reach a point when, in spite of his efforts, he cannot move to a faster tempo. He should then change to a quarter-note pulse (two beats to a bar). Very often this mental switch opens a new reservoir of velocity, and the pianist can progressively increase the speed. After some time, however, he may encounter the same obstacle again: he cannot play any faster. Switching to thinking in whole bars may allow him to conquer the faster tempo. Finally, the student is able to play the étude very fast indeed. If now he tries to enlarge the unit of musical pulse once again, feeling it once every two bars, he may gain a truly virtuoso lightness of playing while feeling much less preoccupied and more in command. This final perception of the musical beat underscores the inseparability of technical and musical considerations, because it coincides with the harmonic rhythm of this piece: two bars of predominantly tonic harmony are followed by two bars governed largely by the dominant. (The effectiveness of switching to progressively larger units of musical pulse depends on appropriate timing of the changes. Delaying the switch stalls the pianist's technical progress. On the other hand, by making the change prematurely, before his technical and musical familiarity with the piece justifies the step, he will cultivate sloppy performance habits.) In rapid passages, enlarging units of pulse means, in fact, that the pianist decreases the frequency of "will impulses" sent by brain to fingers. In other words, the brain sends the fingers "orders" not for every note but for groups of notes that progressively increase in number as the perception of pulse changes. The unfortunate "side effect" of this is that the pianist's ear may stop listening to every note, hearing them in blocks instead; perfunctory playing may result, the see-you-in-the-next-bar phenomenon as described above. The pianist must therefore combine progressively infrequent commands to the fingers with attentive listening to every note. This is just one of many examples of different functions carried simultaneously in the pianist 's brain..."

Amazing. 

Kind of what Kochevitsky scientific approach said.

[BoliverAllmon]

that is interesting. What does everyone else think?

[stringoverstrung]

I agree. I have already experienced this see-you-in-a-bar thing myself (in op25/2).

I also think that mr Berman has a point from a neurological point of view: there is definitely a limit to the speed at which we think/act and it's not so fast as one might imagine. Therefore grouping notes - changing the "imaginary" muscular pulse is an "easy" way to go faster.
Not specifically related to this problem but very helpful in general to understand how the brain works are the excellent books by mr. Damasio:

https://www.uihealthcare.com/depts/med/neurology/neurologymds/damasioa.html

Damasio AR: Descartes' Error: Emotion, Reason and the Human Brain, Grosset/Putnam, New York, 1994; (hardcover); Hayrer Collins, New York, 1995; (paperback).

and even less related:

Damasio AR: The Feeling of What Happens: Body and Emotion in the Making of Consciousness, Harcourt Brace, New York, 1999, 2000.