This bit from Michael Mauboussin’s recent piece, Are You an Expert?, caught my eye:

“Experts perceive patterns in their domain … Rather than focusing on the position of individual pieces, expert chess players perceive clusters of pieces, or chunks. Estimates suggest that chess masters store roughly 50,000 chunks in long-term memory. Notably, this pattern recognition does not represent superior perception ability. When chess pieces are placed randomly on the board, experts remember the positions about as well as novices. The difference amounts to a database of chunks, amassed through deliberate practice, from which experts can draw.”

I think that experienced day traders perceive and interpret intraday price patterns in chunks, at least I do. As the chart builds in real-time you suddenly recognize (unconsciously?) that a low-risk, high probability set-up is in place. Interesting, no?