Lydia Hopper, Ph.D.


Conservation & Science


Lester E. Fisher Center for the Study and Conservation of Apes


Assistant Director


Ph.D. – Psychology, University of St Andrews, UK
B.S. – Psychology & Zoology, University of Liverpool, UK


Areas of Expertise

  • Chimpanzee behavior
  • Primate social cognition
  • Comparative developmental psychology


Lydia joined the Fisher Center in 2012 and now directs the non-invasive behavioral and cognitive research conducted with primates living at Lincoln Park Zoo. Lydia’s research focuses on understanding how primates learn and innovate new skills, either through trial-and-error problem solving or by watching and copying others. Through her research, Lydia has highlighted many nuances of nonhuman primate behavior and has also shown how it compares and relates to our own.

Lydia is also passionate about applying what she discovers about primate cognition to enhance how we care for these animals in zoos and other captive settings. To measure and evaluate primate welfare, Lydia has used a number of established and innovative tools, from observational behavioral assessments to touchscreen tasks that measure mood.

At Lincoln Park Zoo, Lydia directs the Fisher Center’s long-term touchscreen research program and designs other novel tool-use and problem-solving tasks to study primate cognition. She also helps train the next generation of primatologists by promoting the professional development of Fisher Center research assistants and interns, and shares the Fisher Center’s research by working with the zoo’s Learning department to interpret daily touchscreen research sessions for zoo guests.


  • Fiore, A. M., Cronin, K. A., Ross, S. R., & Hopper, L. M. 2020. Food Cleaning by Japanese Macaques: Innate, Innovative or Cultural?. Folia Primatologica; International Journal of Primatology, 1–12.
  • Earl, S. C., Hopper, L. M., & Ross, S. R. 2020. Same Space, Different Species: The Influence of Exhibit Design on the Expression of Zoo-Housed Apes’ Species-Typical Retiring Behaviors. Animals, 10(5), 836.
  • Frankel, J. S., Mallott, E. K., Hopper, L. M., Ross, S. R., & Amato, K. R. 2019. The effect of captivity on the primate gut microbiome varies with host dietary niche. American Journal of Primatology 81(12), e23061.
  • Egelkamp, C. L., Jacobson, S. L., Cronin, K. A., Wagner, K. E., Ross, S. R., & Hopper, L. M. 2019. A Comparison of Sequential Learning Errors Made by Apes and Monkeys Reveals Individual but not Species Differences in Learning. International Journal of Comparative Psychology, 32. Retrieved from
  • Ross, S. R., Hansen, B. K., Hopper, L. M., & Fultz, A. 2019. A unique zoo-sanctuary collaboration for chimpanzees. American Journal of Primatology 81(5): e22941.
  • Hopper, L. M., Egelkamp, C. L., Fidino, M., & Ross, S.R. 2019. An assessment of touchscreens for testing primate food preferences and valuations. Behavior Research Methods, 51(2), 639–650.
  • ManyPrimates, Altschul, D.M., Beran, M.J., Bohn, M., Call, J., DeTroy, S., Duguid, S.J., Egelkamp, C.E., Fichtel, C., Fischer, J., Flessart, M., Hanus, D., Haun, D.B.M., Haux, L.M., Hernandez-Aguilar, R., Herrmann, E., Hopper, L.M., Joly, M., Kano, F., Keupp, S., Melis, A.P., Rodrigo, A.M., Ross, S.R., Sánchez-Amaro, A., Sato, Y., Schmitt, V., Schweinfurth, M.K., Seed, A.M., Taylor, D., Völter, C.J., Warren, E., & Watzek, J. 2019. Establishing an infrastructure for collaboration in primate cognition research. PLoS ONE, 14(10), e0223675.
  • Saiyed, S. T., Hopper, L. M., & Cronin, K. A. 2019. Evaluating the Behavior and Temperament of African Penguins in a Non-Contact Animal Encounter Program. Animals, 9(6), 326.
  • Bonnie, K. E., Bernstein-Kurtycz, L. M., Shender, M. A., Ross, S. R., & Hopper, L. M. 2019. Foraging in a social setting: a comparative analysis of captive gorillas and chimpanzees. Primates, 60(2), 125–131.
  • Jacobson, S.L., & Hopper, L.M. 2019. Hardly habitual: chimpanzees and gorillas show flexibility in their motor responses when presented with a causally-clear task. PeerJ, 7, e6195.
  • Hopper, L. M., Fernandez-Duque, E., & Williams, L. E. 2019. Testing the weekend effect hypothesis: Time of day and lunar phase better predict the timing of births in laboratory-housed primates than day of week. American Journal of Primatology, e23026.
  • Hopper, L. M., & Torrance, A. W.   2019. User innovation: A novel framework for studying animal innovation within a comparative context. Animal Cognition, 22(6), 1185-1190.
  • Hopper, L. M., Cronin, K. A., & Ross, S. R. 2018. A multi-institutional assessment of a short-form personality questionnaire for use with macaques. Zoo Biology, 37: 281-289.
  • Hansen, B., Fultz, A., Hopper, L., & Ross, S.  2018. An evaluation of video cameras for collecting observational data on sanctuary‐housed chimpanzees (Pan troglodytes). Zoo Biology, 37(3), 156–161.
  • Egelkamp, C.L., & Hopper, L.M. 2018. Behavioral and cognitive research. In W. Trevathan (Ed.). The International Encyclopedia of Biological Anthropology. John Wiley and Sons, Inc. (in press).
  • Hopper, L. M., van de Waal, E., & Caldwell, C. A. 2018. Celebrating the continued importance of “Machiavellian Intelligence” 30 years on. Journal of Comparative Psychology, 132(4), 427–431.
  • Watson, S. K., Vale, G. L., Hopper, L. M., Dean, L. G., Kendal, R. L., Price, E. E., … Whiten, A. 2018. Chimpanzees demonstrate individual differences in social information use. Animal Cognition, (Early View).
  • Cronin, K. A., Bethell, E. J., Jacobson, S. L., Egelkamp, C., Hopper, L. M., & Ross, S. R. 2018. Evaluating mood changes in response to anthropogenic noise with a response-slowing task in three species of zoo-housed primates. Animal Behavior and Cognition, 5(2), 209­–221.
  • Hopper, L. M., & Cronin, K. A.   2018. What Did You Get? What Social Learning, Collaboration, Prosocial Behaviour, and Inequity Aversion Tell Us About Primate Social Cognition. In L. D. Di Paolo, F. Di Vincenzo, & F. De Petrillo (Eds.), Evolution of Primate Social Cognition (pp. 13–26). Cham: Springer International Publishing.
  • Cronin, K.A. & Hopper, L.M. 2017. A comparative perspective on helping and fairness. In J. Sommerville & J. Decety (Eds.), Frontiers in Developmental Science Series: Social Cognition. (pp. 26-45). Psychology Press, Taylor & Francis Group, London.
  • Hopper, L.M. 2017. Andrew Whiten. In J. Vonk & T. Shackelford (Eds.), Encyclopedia of Animal Cognition and Behavior (pp. 1-5). Cham: Springer International Publishing.
  • Hopper, L. M. 2017. Cognitive research in zoos. Current Opinion in Behavioral Sciences, 16, 100–110.
  • Howard, L. H., Wagner, K. E., Woodward, A. L., Ross, S. R., & Hopper, L. M. 2017. Social Models Enhance Apes’ Memory for Novel Events. Scientific Reports, 7, 40926.
  • Cronin, K. A., Jacobson, S. L., Bonnie, K. E., & Hopper, L. M. 2017. Studying primate cognition in a social setting to improve validity and welfare: a literature review highlighting successful approaches. PeerJ, 5, e3649.
  • Vale, G., Flynn, E., Kendal, J., Rawlings, B., Hopper, L., Schapiro, S., Lambeth, S., Kendal, R.  2017. Testing differential use of payoff-biased social learning strategies in children and chimpanzees. Proceedings of the Royal Society: Biological Sciences.
  • Jacobson, SL, Hopper, LM, Shender, MA, Ross, SR, Leahy, M & McNernie, J. 2017. Zoo visitors’ perceptions of chimpanzee welfare are not affected by the provision of artificial environmental enrichment devices in a naturalistic exhibit. Journal of Zoo and Aquarium Research, 5(1), 56–61.
  • Wagner, K.E., Hopper, L.M., & Ross, S.R. 2016. Asymmetries in the production of self-directed behaviour by chimpanzees and gorillas during a computerized cognitive test. Animal Cognition. 19(2), 343-350.
  • Hopper, L.M., Shender, M.A., & Ross, S.R. 2016. Behavioral research as physical enrichment for captive chimpanzees. Zoo Biology 35(4), 293-297.
  • Beran, M.J., Hopper, L.M., de Waal, F.B.M., Sayers, K., Brosnan, S.F. 2016. Chimpanzee food preferences, associative learning, and the origins of cooking. Learning & Behavior: 44, 103-108.
  • Beran, M.J., Hopper, L.M., de Waal, F.B.M., Brosnan, S.F., & Sayers, K. 2016. Chimpanzees, cooking, and a more comparative psychology. Learning & Behavior 44, 118-121.
  • Hopper, L.M., Freeman, H.D., & Ross, S.R. 2016. Reconsidering coprophagy as an indicator of negative welfare for captive chimpanzees. Applied Animal Behaviour Science. 176, 112-119.
  • Ross, S.R., & Hopper, L.M. 2016. Seeking a deeper understanding of welfare-related behaviors. Connect. May 2016 Issue, 8-9.
  • Hopper, L.M. 2016. The individual and social drivers of primate innovation. PeerJ Preprints 4, e2276v1.
  • Hopper, L.M., Kurtycz, L.M., Ross, S.R., & Bonnie, K.E. 2015. Captive chimpanzee foraging in a social setting: a test of problem solving, flexibility, and spatial discounting. PeerJ 3, e833.
  • Kendal, R.L., Hopper, L.M., Whiten, A., Brosnan, S.F., Lambeth, S.P., Schapiro, S.J., & Hoppitt, W. 2015. Chimpanzees copy dominant and knowledgeable individuals: implications for cultural diversity. Evolution & Human Behavior. 36, 65-72.
  • Hopper, L.M., Tennie, C., Ross, S.R. & Lonsdorf, E.V. 2015. Chimpanzees create and modify probe-tools functionally: A study with zoo-housed chimpanzees. American Journal of Primatology 77(2), 162-170.
  • Brosnan, S.F., Hopper, L.M., Richey, S., Freeman, H.D., Talbot, C.F., Gosling, S., Lambeth, S.P. & Schapiro, S.J. 2015. Personality influences responses to inequity and contrast in chimpanzees. Animal Behaviour 101, 75-87.
  • Claidière, N., Whiten, A., Mareno, M.C., Messer, E., Brosnan, S.F., Hopper, L.M., Lambeth, S.P., Schapiro, S.J., & McGuigan, N. 2015. Selective and contagious prosocial resource donation in capuchin monkeys, chimpanzees and humans. Scientific Reports 5, 7631.
  • Hopper, L.M., Lambeth, S.P., Schapiro, S.J. & Whiten, A. 2015. The importance of witnessed agency in chimpanzee social learning of tool use. Behavioural Processes 112, 120-129.
  • Finestone, E., Bonnie, K.E., Hopper, L.M., Vreeman, V.M., Lonsdorf, E.V., & Ross, S.R. 2014. The interplay between individual, social, and environmental influences on chimpanzee food choices. Behavioural Processes. 105, 71-78.
  • Hopper, L.M. 2014. Do chimpanzees (Pan troglodytes) choose to exert control over their environment to maximize personal gain in comparison to their peers?. American Society of Primatologists Bulletin, Spring/Summer 2014, 43-52.
  • Hopper, L.M., Price, S.A., Freeman, H.D., Lambeth, S.P., Schapiro, S.J. & Kendal, R.L. 2014. Influence of personality, age, sex, and estrous state on chimpanzee problem-solving success. Animal Cognition. 17(4), 835-847.
  • Brosnan, S.F. & Hopper, L.M. 2014. Psychological limits on animal innovation. Animal Behaviour. 92, 325-332.
  • Hopper, L.M., Lambeth, S.P., Schapiro, S.J., & Brosnan, S.F. 2014. Social comparison mediates chimpanzees’ responses to loss, not frustration. Animal Cognition. 17(6), 1303-1311.
  • Pasquaretta, C., Levé, M., Claidière, N., van de Waal, E., Whiten, A., Macintosh, A., Pelé, M., Bergstrom, M., Borgeaud, C., Brosnan, F., Crofoot, M., Fedigan, L., Fichtel, C., Hopper, L.M., Mareno, M., Petit, O., Schnoell, A.V., Polizzi di Sorrentino, E., Thierry, B., Tiddi, B. & Sueur, C. 2014. Social networks in primates: smart and tolerant species have more efficient networks. Scientific Reports 4, 7600.
  • Hopper, L.M., Morgan, D.B., & Ross, S.R. 2014. The next direction for primatology? A commentary on Setchell (2013). International Journal of Primatology. 35(2), 341-348.
  • Hopper, L.M., Lambeth, S.P., Schapiro, S.J., & Brosnan, S.F. 2013. Chimpanzees (Pan troglodytes) attempt to maximize returns, not ‘level the playing field’. American Journal of Primatology. 75(S1), 43.
  • Brosnan, S.F. & Hopper, L.M. 2013. Cooperation, behavioral diversity and inequity responses. In M. Banaji & S. Gelman (Eds.) Navigating the Social World: What Infants, Children, and Other Species Can Teach Us. Oxford University Press: New York, NY.
  • Freeman, H.D., Brosnan, S.F., Hopper, L.M., Lambeth, S.P., Schapiro, S.J. & Gosling, S.D. 2013. Developing a comprehensive and comparative questionnaire for measuring personality in chimpanzees using a simultaneous top-down/bottom-up design. American Journal of Primatology, 75: 1042-1053.
  • Freeman, H.D., Sullivan, J., Hopper, L.M., Talbot, C.F., Holmes, A.N., Schultz-Darken, N., Williams, L.E. & Brosnan, S.F. 2013. Different responses to reward comparisons by three primate species. PLoS ONE 8(10): e76287.
  • Ross, M.R., Gillespie, K.L., Hopper, L. M., Bloomsmith, M.A., & Maple, T.L. 2013. Differential preference for ultraviolet light among captive birds from three ecological habitats. Applied Animal Behaviour Science 147: 278-285.
  • Hopper, L.M., Holmes, A.N., Williams, L.E., & Brosnan, S.F. 2013. Dissecting the mechanisms of squirrel monkey (Saimiri boliviensis) social learning. PeerJ 1:e13. DOI: 10.7717/peerj.13.
  • Talbot, C.F., Parrish, A.E., Freeman, H.D., Hopper, L.M., Leverett, K., Holmes, A.N., Williams, L.E., & Brosnan, S.F. 2013. Social and individual comparisons are influenced by context. American Journal of Primatology. 75(S1), 98.
  • L. M. Hopper, K. E. Bonnie, L. M. Kurtycz, S. R. Ross 2013. Testing for chimpanzee innovation and social learning in a zoo setting. American Journal of Primatology. 75(S1), 56.
  • Hopper, L.M., Bonnie, K.E., Kurtycz, L.M., & Ross, S.R. 2013. Testing for chimpanzee innovation and social learning in a zoo setting. American Journal of Primatology. 75(S1), 56.
  • Hopper, L.M., Lambeth, S.P., Schapiro S.J., Bernacky, B.J., & Brosnan, S.F. 2013. The ontogeny of social comparisons in rhesus macaques (Macaca mulatta). Journal of Primatology, 2:109.
  • Hopper, L.M., Lambeth, S.P., Schapiro, S.J. & Brosnan S.F. 2013. When given the opportunity, chimpanzees maximize personal gain rather than ‘level the playing field’. PeerJ. 1: e165.
  • Hopper, L.M., Lambeth, S.P. & Schapiro, S.J. 2012. An evaluation of the efficacy of video displays for use with chimpanzees (Pan troglodytes). American Journal of Primatology. 74, 442-449.
  • Caldwell. C.A., Schillinger, K., Evans, C.L., & Hopper, L.M. 2012. End state copying by humans (Homo sapiens): Implications for a comparative perspective on cumulative culture. Journal of Comparative Psychology. 126, 161-169.
  • Hopper, L.M. & Brosnan, S.F. 2012. Primate cognition. Nature Education Knowledge 3(6):1.
  • Hopper, L.M., Marshall-Pescini, S. & Whiten, A. 2012. Social learning and culture in child and chimpanzee. In F.B.M. de Waal & P.F. Ferrari (Eds.) The Primate Mind: Built to Connect with Other Minds. (pp. 99-118). Harvard University Press: Cambridge, MA.
  • Hopper, L.M. & Whiten, A. 2012. The evolutionary and comparative psychology of social learning and culture. In J. Vonk & T. K. Shackelford (Eds.) The Oxford Handbook of Comparative Evolutionary Psychology. (pp.451-473). Oxford University Press: New York, NY.
  • Brosnan, S.F., Hopper, L.M., Lambeth, S.P. Schapiro, S.J., & Bernacky, B.J. 2012. The ontogeny of social comparisons by rhesus macaques (Macaca mulatta). American Journal of Primatology. 74(S1), 57.
  • Jacobsen, K.R., Hopper, L.M., McAdams, T., Merino, R., Sherenco, K., Lambeth, S.P., & Schapiro, S.J. 2011. Characterization of alopecia in four species of non-human primates. American Journal of Primatology. 73(S1), 81.
  • Hopper, L.M., Lambeth, S.P., Schapiro, S.J., & Brosnan, S.F. 2011. Chimpanzees’ (Pan troglodytes) learning indicates both conformity and conservatism. American Journal of Primatology. 73(S1), 77.
  • Hopper, L.M., Schapiro, S.J., Lambeth, S.P. & Brosnan, S.F. 2011. Chimpanzees’ socially maintained food preferences indicate both conservatism and conformity. Animal Behaviour. 81, 1195-1202.
  • Price, S.A., Hopper, L.M., Schapiro, S.J., Lambeth, S.P., & Kendal, R. 2011. Influences of personal and social information on chimpanzees (Pan troglodytes) using a foraging task. American Journal of Primatology. 73(S1), 62.
  • Hopper, L.M. 2010. ‘Ghost’ experiments and the dissection of social learning in humans and animals. Biological Reviews. 85, 685-701.
  • Hopper, L.M. 2010. Deferred imitation in children and apes. Children imitate after a delay, but can apes ape in a similar fashion?. The Psychologist. 23, 294-297.
  • Hopper, L.M., Flynn, E., Wood, L.A.N. & Whiten, A. 2010. Observational learning of tool use in children: Investigating cultural spread through diffusion chains and learning mechanisms through ghost displays. Journal of Experimental Child Psychology. 106, 82-97.
  • Whiten, A., McGuigan, N., Marshall-Pescini, S. & Hopper, L.M. 2009. Emulation, imitation, over-imitation and the scope of culture for child and chimpanzee. Philosophical Transactions of the Royal Society B. 364, 2417-2428.
  • Hopper, L.M., Lambeth, S.P., Schapiro, S.J. & Whiten, A. 2008. Observational learning in chimpanzees and children studied through ‘ghost’ conditions. Proceedings of the Royal Society B. 275, 835’840.
  • Hopper, L.M., Spiteri, A., Lambeth, S.P., Schapiro, S.J., Horner, V. & Whiten, A. 2007. Experimental studies of traditions and underlying transmission processes in chimpanzees. Animal Behaviour.73, 1021-1032.