Kim's research has demonstrated that the acquisition and retrieval of fear memories is different across childhood, adolescence, and adulthood, and that fear memories are able to be erased early in life. Kim's research uses rodent models that closely resemble human behaviors to understand the neurobiological basis of those behaviors. Specifically, her work investigates the role of memory and forgetting in the development and treatment of two major mental disorders across childhood and adolescence: anxiety disorder and substance use disorder.[citation needed]