Are chimpanzees and bonobos more attentive to familiar ingroup members or unfamiliar strangers? Intergroup interactions in bonobos seem to be significantly less hostile as compared to those of chimpanzees. In fact, bonobos have been shown to travel, copulate, play, rest with, and groom individuals from neighboring groups (Wrangham, 1999; Furuichi, 2011; Tan & Hare, 2013), while chimpanzees are known to engage in much more hostile, and sometimes lethal, interactions with neighboring groups. Using cutting-edge eye-tracking technology, our first study seeks to explore whether chimpanzees and bonobos demonstrate any differences in attention toward ingroup members as compared to outgroup members based on these disparities in their natural socioecology. In a second study, we use this same eye-tracking technology to test chimpanzee and bonobo long-term memory of social groupmates. After many years, do chimpanzees and bonobos treat past groupmates as unfamiliar strangers? To what extent do chimpanzees and bonobos remember their old groupmates? We will present preliminary data on these two comparative 

Are chimpanzees and bonobos more attentive to familiar ingroup members or unfamiliar strangers? Intergroup interactions in bonobos seem to be significantly less hostile as compared to those of chimpanzees. In fact, bonobos have been shown to travel, copulate, play, rest with, and groom individuals from neighboring groups (Wrangham, 1999; Furuichi, 2011; Tan & Hare, 2013), while chimpanzees are known to engage in much more hostile, and sometimes lethal, interactions with neighboring groups. Using cutting-edge eye-tracking technology, our first study seeks to explore whether chimpanzees and bonobos demonstrate any differences in attention toward ingroup members as compared to outgroup members based on these disparities in their natural socioecology. In a second study, we use this same eye-tracking technology to test chimpanzee and bonobo long-term memory of social groupmates. After many years, do chimpanzees and bonobos treat past groupmates as unfamiliar strangers? To what extent do chimpanzees and bonobos remember their old groupmates? We will present preliminary data on these two comparative studies, and discuss the implications of differences in cognitive processing of groupmates and strangers based on disparities in these species’ socio-ecologies.