Go to the shack of a veteran CW operator, or visit the CW station at a club Field Day operation. Watch people copy and send code at 30 to 35 wpm. You’ll notice they’re pretty relaxed about it; they’re not sweating each character as it comes out of the speaker and they’re not racking their brains to “figure out” what’s being sent. Code has become second nature to them.
That’s the key to code proficiency. Copying code must be a thought-free process. When you hear a character, you should know, without thinking, what it is. It should be a reflex. In fact, copying above about 10 wpm can only be done by reflex. Above that speed, thought processes are too slow to succeed.
That’s why slow code is a deadly trap, and why traditional amateur methods of code training are so painful and frustrating. Most hams are told to memorize all the characters, then start building their speed. When you do it this way, you build a “lookup table” in your brain, comparing each character you hear with those in the lookup table until you find a match. This process shuts down from overload at about 10 wpm. That’s why people experience a “plateau” at 10 wpm, and don’t see any progress for weeks or months.
Those who finally get over that “hump” and progress beyond 10 wpm do so because, through constant practice, they have begun to copy code by reflex instead of by thought. They are the lucky ones; this 10 wpm barrier is where many folks give up out of frustration.
Code training, then, should completely bypass the lookup-table phase and begin by building copying proficiency as a reflex. This was recognized in the 1930s by the German psychologist Ludwig Koch, who devised the most efficient method known for Morse training.
Extract from “So You Want To Learn Morse Code” by David Finley N1IRZ