Expertise requires building sophisticated chunk recoding schemes

In many fields, experts become experts mostly by developing more sophisticated mental representations (Mental representations, after Ericsson and Pool), which amounts to increasing the size of their mental chunks (“Chunks” in human cognition). This increases their information processing capacity (Human channel capacity increases with bits-per-chunk, Recoding can increase chunk size). This happens through practice: Good practice encodes more effective chunk recoding schemes

What sets expert performers apart from everyone else is the quality and quantity of their mental representations.
(Ericsson and Pool, 2016, p. 62, not well-cited)

For example, the model developed by Simon and Gilmartin (1973) suggests that chess masters have encoded order tens of thousands of chunks. (See also Chase and Simon - Perception in chess)

Knowledge work often requires solving search problems. Ericsson and Pool suggest that expert search performance comes from more complex chunk schemas (2016, p. 70-72). The argument’s not made very strongly, but because Human channel capacity increases with bits-per-chunk, this would seem to explain superior culling and feedback-uptake performance.


Simon, H. A., & Gilmartin, K. (1973). A simulation of memory for chess positions. Cognitive Psychology, 5(1), 29–46.

Ericsson, A., & Pool, R. (2016). Peak: Secrets from the New Science of Expertise (1 edition). Eamon Dolan/Houghton Mifflin Harcourt. Peak - Ericsson and Pool