Over the last century many individuals with exceptional memory have been studied and tested in the laboratory. This article studies Chao Lu, who set a Guinness World Record by memorizing 67,890 decimals of pi. Chao Lu’s superior self-paced memorization of digits is shown through analyses of study times and verbal reports to be mediated by mnemonic encoding and retrieval processes. Furthermore, Chao Lu’s development of his superior memory for decimals of pi is consistent with his engagement in thousands of hours of memorization. In contrast to most other studied memorists, who have digit spans over 15 digits, Chao Lu exhibited a digit span in only the normal range. Implications for different types of memorization skills and associated practice activities are discussed.

The ability to memorize poems and books verbatim and to memorize other lists has been the focus of fascination since the beginning of our culture. The first systematic studies of individuals with exceptional memory were conducted by Binet (1894) in his studies of mental calculation experts and mnemonists, followed by the studies of Müller (1911, 1913, 1917), Luria (1968), and several others (for reviews see Brown & Deffenbacher, 1975, 1988;