Recoding can increase chunk size

Human channel capacity increases with bits-per-chunk. But we don’t need to rely on the “intrinsic” chunk size of a stimulus. It’s possible to increase the effective chunk size of stimuli by recoding them—that is, mentally regrouping them into chunks representing larger patterns. These chunk schemas are also called Mental representations, after Ericsson and Pool.

For example, when trying to memorize a sequence of binary digits, one can instead memorize them as octets (e.g. 010 = 2, 101 = 5, etc), which will roughly triple your capacity (Miller, 1956). Chase and Ericsson (1982) used this technique to build a student’s digit span to 80 digits, via hierarchical recoding into 4-decimal-digit chunks.

This process is important not just because it helps us remember useful information, but because it’s likely the key to how anyone processes any kind of complex material (in particular, Expertise requires building sophisticated chunk recoding schemes). A pianist initially reads individual notes (C, E, G—ah, a C chord!) but later sees that shape as a single chord (ah, a C major triad). It’s not possible to sight-read music of any real complexity with the former-approach.

These patterns (e.g. the shape of a major triad) can only be used as “chunks” once they’re stored in long-term memory.

Chase and Simon - Perception in chess record experimental data suggesting that chess masters use larger chunk sizes (and possibly hierarchical chunk configurations).

Related: Complex ideas may be hard to learn in part because their components overflow working memory


Chase, W. G., & Ericsson, K. A. (1982). Skill and Working Memory. In G. H. Bower (Ed.), Psychology of Learning and Motivation (Vol. 16, pp. 1–58). Academic Press.

Miller, G. A. (1956). The magical number seven, plus or minus two: Some limits on our capacity for processing information. Psychological Review, 63(2), 81–97. Miller - The magical number seven, plus or minus two

Last updated 2023-07-13.