This paper introduces the republished version of selected parts of an article written in 1897 by the Italian psychologists and psychiatrists Giuseppe Guicciardi and Giulio Cesare Ferrari on the ‘mental calculator’ Ugo Zaneboni. The paper highlights how the two Italian scholars were inspired mostly by French experimental psychology and, in particular, by the research of Alfred Binet. Furthermore, extracts of two unpublished letters written to the authors by Cesare Lombroso and Nicolae Vaschide are also presented.