What does it mean that expertise is efficient signal processing?

Experts do not process more information than novices. They process less — because they have learned which information to ignore. Expertise is not faster consumption. It is superior filtration.

Example: Two emergency physicians look at the same ECG strip. The junior resident reads it methodically — rate, rhythm, axis, intervals, segments, morphology — working through a mental checklist of twenty-plus features. It takes her ninety seconds to reach a tentative conclusion. The attending glances at the strip for under three seconds and says: 'Anterior STEMI. Activate the cath lab.' She did not process the strip faster. She processed less of it. Twenty years of pattern exposure taught her exactly which features matter for this class of abnormality and which are irrelevant. The resident sees data. The attending sees signal. They are looking at the same strip, but they are not seeing the same thing.

Try this: Choose a domain where you have genuine expertise — your profession, a deep hobby, a subject you have studied for years. Now choose a domain where you are a novice — something you started recently or know little about. For each domain, spend ten minutes consuming new information (an article, a video, a document). As you consume, notice and log: (1) how quickly you can identify what matters, (2) how much of the content you skip or skim without losing comprehension, (3) how many connections you make to things you already know, (4) how confident you feel about what to ignore. Compare the two experiences. The gap between them is the gap between having signal detectors and not having them. That gap is what this lesson explains.