Stephen Kaplan is a prominent psychologist known for his work in environmental psychology. He has contributed significantly to understanding how people interact with their surroundings, particularly in natural and urban settings. His research often focuses on the psychological benefits of nature and how environments can influence well-being. Kaplan is also recognized for developing the Attention Restoration Theory, which suggests that natural environments can help restore mental fatigue. This theory emphasizes the importance of nature in promoting cognitive function and emotional health, highlighting the need for green spaces in urban planning and design.