The Winter 2011 issue of the American Journal of Psychology includes a new translation of German psychologist Karl Marbe‘s work with the chimpanzee Basso (above). Marbe (right) began to work with Basso after the chimpanzee attracted great attention at the Frankfurt zoo for her apparent arithmetical skills. As Marbe describes in his autobiographical chapter in Carl Murchison’s series, History of Psychology in Autobiography,

This animal had brought thousands and hundreds of thousands of people into the Frankfort zoo to admire its arithmetical skill. Before her lay a pile of little tablets upon which the numbers from 1 to 10 had been written. Then the caretaker said, for example, “Basso, how much is 10 minus 8?” whereupon the chimpanzee took a tablet into her hand upon which stood the number 2. The caretaker thought that he had systematically instructed Basso in arithmetic, but then became convinced that, after all, her achievements were due not to instruction but rather to thought transference. The superintendent of the zoo was not able to account for the behavior of the chimpanzee. And when, while I was temporarily staying in Frankfort, I had occasion to see Basso at work, I too was completely at a loss.

Marbe came to undertake a number of systematic investigations with the chimpanzee in an effort to explain Basso’s arithmetic abilities. As in the earlier case of Clever Hans – the horse who could perform simple calculations – Marbe found that it was the subtle, unconscious movements of Basso’s keeper that were cuing the chimpanzee into the answers to the arithmetic questions being posed.

Read the English translation of Marbe’s account of his research on Basso in “Arithmetic in the Chimpanzee Basso in the Frankfurt Zoological Park Together With Remarks to Animal Psychology and an Open Letter to Herr Krall From Karl Marbe,” translated by Heidi L. Shaw and with an introduction by R. Allen Garner.