Walter Mischel was an Austrian-born American psychologist renowned for his pioneering research on personality theory and social psychology. He is best known for the "Marshmallow Test," a groundbreaking study on delayed gratification, which has profoundly impacted his understanding of self-control and its implications for life outcomes. Mischel held the esteemed position of Robert Johnston Niven Professor of Humane Letters in the Department of Psychology at Columbia University, and his work earned him a place among the most cited psychologists of the 20th century.

Born in Vienna in 1930, Mischel fled to the United States with his family following the Nazi occupation. He grew up in Brooklyn, New York, where he excelled academically, earning a scholarship to New York University. Initially pursuing premedical studies, he shifted his focus to psychology, obtaining his bachelor's degree in 1951 and later earning a Ph.D. in clinical psychology from Ohio State University in 1956. His academic journey included teaching positions at several prestigious institutions, such as Harvard University and Stanford University, before joining Columbia University in 1983.

Mischel's "Marshmallow Test" demonstrated that children's ability to delay gratification predicted significant long-term outcomes like academic success and better health. His research suggested that self-control could be learned and served as a protective buffer against various vulnerabilities later in life. This work advanced psychological science and influenced behavioural economics and education policy fields.

Mischel received numerous accolades throughout his career, including election to the American Academy of Arts and Sciences and the National Academy of Sciences. He was also awarded the University of Louisville Grawemeyer Award for Psychology in 2011. Beyond his professional achievements, Mischel enjoyed painting and traveling, often in Paris and Bend, Oregon. He resided in Manhattan until his passing in 2018.