
Token-Exchange Studies

Studying How Apes Respond to Unequal Treatment
Like humans, chimpanzees respond negatively to inequity. So when a chimpanzee receives a less-preferred food reward than that of a groupmate, it often shows frustration by rejecting the lesser reward.
Such responses to inequity, although robust, appear to vary across individuals and social contexts. To understand why, scientists at the Fisher Center are running studies to determine the circumstances under which chimpanzees respond to inequity. By setting up a system where apes can exchange tokens for foods of varying desirability, the scientists can alter rewards and study responses in the group.
Unlike chimpanzees, scientists know very little about whether gorillas respond to inequity. A parallel project will enable some first comparisons between chimpanzees and gorillas on the subject. Through these comparative studies, we aim to explore many unanswered questions about gorillas’ understanding of behavioral economics.
Staff
![]() |
Steve Ross, Ph.D. |
![]() |
Lydia Hopper, Ph.D. |
![]() |
Laura Kurtycz |
![]() |
Kristin Bonnie, Ph.D. |
Conservation & Science
- Focuses
- Projects
- Gombe Field Research
- Serengeti Health Initiative
- Goualougo Triangle Ape Project
- Chimpanzee SSP
- Surveying Lincoln Park's Bird Species
- Eastern Massasauga Rattlesnake Recovery Efforts
- Black Rhinoceros Conservation in Addo Elephant National Park
- Restoring the Smooth Green Snake
- Lincoln Park Zoo's Project ChimpCARE
- Chimps Should Be Chimps
- ChimpDATA
- Protecting the Puerto Rican Parrot
- The Mind of the Chimpanzee
- Urban Wildlife Biodiversity Monitoring
- Rabbit Management Study at Lincoln Park Zoo
- Urban Black-tailed Prairie Dog Ecology
- ZooRisk
- Avian Reintroduction and Translocation Database
- Conserving the Black-Footed Ferret
- PMCTrack
- Predicting Capacity for African Ape Sanctuaries
- PopLink
- Ape Tool-Use Studies
- Ape Touch-Screen Studies
- Data Standards for Animal Records Databases
- Ethically Managing Free-Roaming Cat Populations
- Great Ape Blood Typing
- Modeling the Future of Zoo and Aquarium Populations
- Monitoring Ape Behavior
- Monitoring Bat Diversity in and Around Chicago
- Ornate Box Turtle Population Recovery in Illinois
- Tarangire Elephant Modeling
- The Outcomes of Wildlife Relocation
- Token-Exchange Studies
- Science Centers
- Resources












