Memory and Social Cognition in Chimpanzees and Bonobos: Eye-Tracking Reveals Long-Term Group-Mate Recognition

In Speaking of Psychology, Dr. Laura Simone Lewis explains how chimpanzees and bonobos recognize former groupmates after years apart using noninvasive eye-tracking to reveal long-term social memory. She describes experiments showing apes spend more time looking at images of past groupmates than strangers, with stronger attention when previous relationships were positive. The discussion covers fieldwork at the Ngaba Island Chimpanzee Sanctuary in Uganda, semi-wild populations, and cross-species parallels to human memory and social cognition. The episode also touches on memory in other animals and a curious study where children and chimps watch videos of social interactions, highlighting how social information shapes attention and curiosity. Lewis outlines future directions for her BO Lab.

Overview and evolutionary context

Dr. Laura Simone Lewis, an assistant professor at UC Santa Barbara, studies social cognition in chimpanzees and bonobos to understand what makes humans unique and what we share with our closest relatives. She explains that humans and these primates last shared a common ancestor roughly 5 to 9 million years ago, and that we share about 99% of our DNA. This close relationship yields numerous similarities in social psychology, including how individuals identify and remember others within large, fission–fusion groups that resemble human social networks. The conversation emphasizes that memory for others is not merely about recognition, but about the content and quality of social relationships that shape how memories are organized over years.