The psychologist who famously demonstrated the importance of being able to delay gratification to achieving later success in life died on September 12 in New York City. Walter Mischel, emeritus professor of psychology at Columbia University and self-proclaimed "Marshmallow Man," was 88.

Per Columbia University's announcement:

"Professor Mischel is revered for his work in self-regulation. He is the author of the popular book The Marshmallow Test: Mastering Self-Control. In it, he describes his groundbreaking studies of young children in the 1960s and 1970s, during which they were given the choice between receiving one immediate treat and receiving two treats 15 minutes later. The tactics used by the youngsters to distract themselves had implications for delayed gratification in adults. For example, when faced with the urge to smoke or a choice between arguing versus compromise, Mischel recommended keeping a goal in mind and focusing on the consequences of losing self-control."

Mischel's landmark behavioral study involved 600 kids between the ages of four and six, all culled from Stanford University's Bing Nursery School. He would give each child a marshmallow and gave them the option of eating it immediately if they chose. But if they could wait 15 minutes, they would get a second marshmallow as a reward. Then Mischel would leave the room and a hidden video camera would tape what happened next.

Some kids just ate the marshmallow right away. Others found a handy distraction: covering their eyes, kicking the desk, or poking at the marshmallow with their fingers. Some smelled it, licked it, or took tiny nibbles around the edges, hoping the examiner wouldn't notice. Roughly one-third of the kids held out long enough to earn a second marshmallow. Several years later, Mischel noticed a strong correlation between the success of some of those kids later in life (better grades, higher self confidence) and their ability to delay gratification in nursery school. Mischel's follow-up study confirmed the correlation.

"The capacity to hold out for a second marshmallow is shaped in large part by a child's social and economic background."

Earlier this year, a study published in the journal Psychological Science that replicated the marshmallow test with preschoolers concluded the picture is a bit more nuanced. It found the same correlation between later achievement and the ability to resist temptation in preschool, but it was much less significant after the researchers factored in such aspects as family background, home environment, and so forth. "The capacity to hold out for a second marshmallow is shaped in large part by a child's social and economic background—and, in turn, that that background, not the ability to delay gratification, is what's behind kids' long-term success," co-author Jessica McCrory Calarco of Indiana University wrote in The Atlantic in July.

Mischel himself advised caution when interpreting his original findings. “The idea that your child is doomed if she chooses not to wait for her marshmallows is really a serious misinterpretation,” he told PBS in 2015.

Mischel was born in Vienna, Austria, in 1930; his family fled the Nazi occupation in 1938 and moved to the United States. He went on to earn his PhD in clinical psychology from Ohio State University, teaching at the University of Colorado, Harvard, and Stanford (where he conducted his famous Marshmallow Test) before moving to Columbia in 1983. He is among the most cited psychologists of the 20th century. Part of his interest in delayed gratification stemmed from his own three-pack-a-day smoking habit; he kept trying, and failing, to quit.

Mischel is survived by his wife, Michele Tolela Myers, three daughters, and several grandchildren. "Walter was a living legend in psychology yet a humble mentor and colleague. We will miss him dearly." said Carl Hart, chair of Columbia's Department of Psychology and the Ziff Professor of Psychology.