Research - Brenda de Groot

Research_

Social Interactions of Delacour’s Langurs (T. delacouri) and Hatinh Langurs (T. hatinhensis)

Keywords: Infant handling, allomothering, primate communication, social interaction

Delacour’s and Hatinh langurs are (critically) endangered leaf-eating monkeys that inhabit the limestone forests of northern Vietnam. They belong to the colobines, a diverse group of primates whose social behavior and cognition remains comparatively understudied relative to cercopithecines (macaques, baboons, guenons) and apes. One striking feature of these langurs is their bright orange infants, which attract considerable social attention from other group members. My research focuses on the interactions that emerge around and with these infants, including caregiving, infant handling, communication, and social coordination between individuals. By closely observing these everyday interactions, I aim to contribute to a broader understanding of social behavior and communication in primates, as well as the diversity of social life among the lesser-studied colobines.

Advisor: Dr. Ikki Matsuda

Delacour's langur (Trachypithecus delacouri) with orange infant.

The Moral Standing of Animals

The psychology of speciesism

How much moral concern do we have for different animals? And to what extend does their sentience, cognitive capacity and likability explain their respecitve places on the circle of moral concern? This study explores people’s evaluations of moral standing of a large range of animal species, and the cognitive and affective determinants that contribute to this evaluation.

Collaborators: Jacy Reese Anthis, Dr. Tom Wilderjans, Dr. Matti Wilks, Dr. Mariska Kret

Publications_

Journal articles

Straffon, L. M., de Groot, B., Gorr, N. D., Tsou, Y. T., & Kret, M. E. (2024). Developing drawing skill: Exploring the role of parental support and cultural learning. Cognitive Development, 70, 101444.
De Groot, B., Gorr, N.D., Kret, M.E., Rieffe, C., Tsou, Y.T., & Mendoza Straffon, L. (2023). Development and preliminary validation of a questionnaire to measure parental support for drawing. Journal of Thinking Skills and Creativity, 101228. https://doi.org/10.1016/j.tsc.2022.101228
De Groot, B., and Cheyne, S.M. (2016). Does mirror-enrichment improve primate well-being? Animal Welfare 25(2), 163 – 170. https://www.ufaw.org.uk/downloads/de-groot.pdf
De Groot, B., and Nekaris, K.A.I. (2016). Ecology of the Germain’s Langur (Trachypithecus germaini) in a pre-release environment and the implications for its conservation. Asian Primates Journal 6(1), 2 – 14. https://tinyurl.com/tgermaini

Presentations

De Groot, B. (2026, January 16). Allomothering in Delacour’s langurs and Hatinh langurs at the Endangered Primate Rescue Center [Invited talk]. CPNP Conference, 16 January, Cuc Phuong National Park, Vietnam.
De Groot, B. (2025, October 14). On the need and value of ethnography for understanding animals [Invited talk]. CIFAR workshop Multispecies Societies and Social Norms in Animals. 11–20 October, Valparai, India.
De Groot, B. Anthis, J.R., Wilks, M., Kret, M.E. (2025, May 22). Psychology for multispecies justice [Oral presentation]. The Politics of Not Eating Animals Conference. 22–23 May, Amsterdam, The Netherlands.
De Groot, B. (2023, July 20). Theory of Sentience: A concept for ascribing sentience to other beings. Diverse Intelligences Summit 2023. St. Andrews, Scotland.
De Groot, B. (2023, May 26). The animal revolution: Towards a post-anthropocentric paradigm shift in science and beyond. Social Sciences Honours Conference, Leiden University, The Netherlands.
De Groot, B. (2022, August 1). Animal ethnography: A cross-disciplinary approach for understanding animals. Diverse Intelligences Summit 2022, St. Andrews, Scotland.

Posters

De Groot, B. (2025, December 6-7). Patterns and dynamics of infant transfers in Hatinh langurs (Trachypithecus hatinhensis) and Delacour’s langurs (T. delacouri). Biodiversity and Wildlife 2025 Symposium, Kasetsart University, Bangkok, Thailand.
De Groot, B. (2025, November 17-18). Patterns and dynamics of infant transfers in Hatinh langurs (Trachypithecus hatinhensis) and Delacour’s langurs (T. delacouri). International Primatology and Wildlife Science Symposium (2025), Kyoto University, Kyoto, Japan.
De Groot, B., Anthis, J.R., Wilks, M., Kret, M.E. (2023, June 22-24). Mapping the moral standing of animals. PHAIR Society Animal Advocacy Conference, Canterbury, UK.
De Groot, B., Gorr, N.D., Kret, M.E., Rieffe, C., Tsou, Y., & Mendoza-Straffon L. (2021, September 10). Preliminary development and validation of a questionnaire to measure parental support for drawing. [Poster presentation]. EADP Summer Tour, Poland (online). https://www.eadp.info View poster
De Groot, B. and Nekaris, K. A. I. (2018, November 28-30). Humble mysteries: Studying the unknown lives of leaf-eating monkeys. [Poster presentation]. NVG 26th annual meeting, Egmond aan Zee, The Netherlands. https://www.gedragsbiologie.nl/meetings/ View poster
De Groot, B. and Ploeger, A. (2015, April 16-17). Primate empathy: Review of the evidence in two taxa. [Poster presentation]. Evolutionary Psychology & Primatology in the Low Countries, Conference organised by CBEN, Amsterdam, The Netherlands. http://www.cognitionbehaviorevolution.nl

Other

De Groot, B. (2019). Conserving livelihoods and the Chamba Sacred Langur. Zoo’s Print, 34(8), 8 – 9. View issue

Grants, Fellowships and Awards_

Research grants

International Primatological Society — Small Research Grant (2026)
Stichting het Kronendak — PhD Thesis Grant (2026)
Australasian Animal Studies Association (AASA) — Activity Fund for pilot study on langur social behavior in Vietnam (2024)
Mohamed Bin Zayed Species Conservation Fund — Conservation grant for creating educational magazines for the Himalayan Langur Project (2015)
Mohamed Bin Zayed Species Conservation Fund — Conservation grant for MSc thesis project (2014)
Primate Society of Great Britain — Conservation Grant Award for MSc thesis project (2014)
Born Free Foundation — Small Grant for MSc thesis project(2014)

Scholarships & Fellowships

Monbukagakusho (MEXT) Scholarship — Doctoral Scholarship, Kyoto University (2025–2028)
UCLA Asia Pacific Center — Hiroshi Wagatsuma Memorial Fellowship for study on Japanese primatology (2024)
Prins Bernhard Cultuurfonds — PhD Scholarship (2023–2024)
Dr Hendrik Muller’s Vaderlandsch Fonds — PhD Scholarship (2023–2024)
UCLA Department of Anthropology — Predoctoral Fellowship, UCLA (2023)
Diverse Intelligences Summer Institute — Alumni fellowship (2022)
Diverse Intelligences Summer Institute Fellowship — Fellowship (2021)

Awards

Outstanding Poster Award — Biodiversity and Wildlife Symposium, Kasetsart University (2025)
Excellent Poster Award — The 20th Primatology and Wildlife Science Symposium, Kyoto University (2025)

Media_

Interview for Study International about my research and experience as an international scholar in Japan

Interview for 60 second scientist by Kristyn Sommer about what adults can learn from children if it comes to seeing and respecting animals.

Primate behaviour advisor for AAPa children’s series broadcasted on Dutch public television. I advised Yannik Josefzoon as he played the main character, a gorilla. (Fun fact: the director named the gorilla Benedict de Groot. I said I’d put it on my CV.)

Podcast guest at Helden en Hordes on veganism, speciesism, cognitive dissonance reduction, biophilia and sentientism