Tool assisted task on touchscreen: a case study on drawing behaviour in chimpanzees (Pan troglodytes)

Observations of drawing behaviour in chimpanzees have often focused on the completed drawings. Here, we compared drawing behaviour using fingers or tools on a touch-sensitive monitor between five chimpanzees from the Kumamoto Sanctuary (KS) and two from the Primate Research Institute (PRI), both located at Kyoto University, Japan. Regarding drawing duration, both PRI females drew relatively longer than the other, with the exception of one KS female. However, a long drawing duration did not correspond with a decrease in the number of pauses, which can be interpreted as a lack of concentration or interest. Therefore, to better understand the engagement of individuals, we recorded the time spent looking at the touchscreen. Pan, one of the two PRI females, had the longest drawing periods and spent the most time looking at the screen. We compared her with Ai, the other PRI female, to better understand their individual marking techniques and behaviours. By adapting to each one's specific behaviour and previous experience with tool-assisted drawing on paper, we offered the females appropriate tools for making marks on the touchscreen. Our results indicate that electronic devices are not limiting in the expression of drawing behaviour. The females did not have the same drawing technique and also showed different types of engagement as motivation, which could not have been detected by only studying the completed drawings. By focusing more on the process rather than on the drawings themselves, we try to show inter-individual differences in drawing behaviour of chimpanzees and the relevance to adapt to it as experimenters.