Fauna Foundation Chimpanzee Tatu

Sign Language Studies with Chimpanzees

During my internship at Fauna in 2018, I was introduced to sign language studies with chimpanzees. I looked at some of the past and present research related to the use of American Sign Language (ASL) as a mode of communication for Tatu and Loulis. Tatu and Loulis learned ASL as infants and continue to use signs in their daily lives. They use ASL to navigate social interactions, express their thoughts or desires, or make comments on the world around them. They use signs during interactions with signing and non-signing caregivers and other chimpanzees. Fauna caregivers record and archive sign logs, which are detailed documentation of Tatu and Loulis’ signed and non-signed behaviour.

Analyzing sign logs to assess communicative function

As part of the research component of my Fauna Internship in 2018, with Dr. Mary Lee Jensvold as contributor and co-author, I was given the opportunity to analyze some of the more recent sign logs, with the goal of assessing the communicative function of the utterances. To clarify, an utterance can be considered the basic unit of communication, and communicative function is the intent underlying an utterance. A previous publication by Leeds and Jensvold in 2013 entitled The Communicative Functions of Five Signing Chimpanzees (Pan troglodytes)1 studied patterns of communicative function for Tatu, Loulis, Washoe, Moja and Dar while they were living at the Chimpanzee and Human Communication Institute (CHCI) in Ellensburg, Washington. This publication inspired my project, entitled Communicative Function in The Utterances of Two Signing Chimpanzees2.

Sign Language Studies with Chimpanzees - Dr. Mary Lee Jensvold with Tatu

Most frequent utterances by category

I analyzed a total of 103 utterances and categorized the communicative functions into one or more of seven categories: Request, Response, Description, Performative, Statement, Conversational Device, or Uninterpretable. I also looked at the different category frequencies between Chimpanzee-to-Human interactions (CH) and Chimpanzee-to-Chimpanzee interactions (CC), as well as comparing my results with those in Leeds and Jensvold (2013). In CH interactions, the most frequent categories were Response (37%), Request (27%), and Description (21%). In CC interactions, the most frequent categories were Conversational Device (39%), Performative (22%), and Uninterpretable (19%). My results showed that the distribution of categories was significantly different between the two types of interactions, CC vs. CH, and the distribution of categories in the current study period was significantly different than Leeds; although, Request was the most frequent category in the CH interactions across both studies.

In December 2020, I presented a poster of my main findings from the sign language studies with chimpanzees at the Société Québecoise pour l’Étude Biologique du Comportement Virtual Conference, as part of the Animal Cognition section hosted by Université de Montréal. This was a great opportunity to showcase some of the ongoing research happening at Fauna, as well as a chance to highlight some of our findings on ASL communication in signing chimpanzees. To learn more about my results and findings, you can view the full presentation (French) or download the poster (English).

By Emily Collins, Fauna Intern

1Leeds, CA and Jensvold, ML. The Communicative Functions of Five Signing Chimpanzees (Pan troglodytes). Pragmat. Cogn. 2013; 21(1):224–247. https://doi.org/10.1075/pc.21.1.10lee.

2 Collins, E. & Jensvold, M.L. Communicative Function of Utterances in Two Signing Chimpanzees. Poster and Presentation at Conférence Virtuelle SQEBC 2020 (Société Québecoise pour l’Étude Biologique du Comportement). December 10, 2020.