Walter Mischel was the inventor of the famous marshmallow test

Walter Mischel, whose studies of delayed gratification in children clarified the importance of self-control in human development, and whose work led to a broad reconsideration of how personality is understood, died Wednesday at his home in New York. He was 88.

The cause was pancreatic cancer, his daughter Linda Mischel Eisner said.

Mr. Mischel was probably best known for the marshmallow test, which challenged children to wait before eating a treat. That test and others like it grew in part out of his deepening frustration with the predominant personality models of the mid-20th century.

One model was rooted in Freudian thinking and saw people as prisms of unconscious, often conflicting desires. The other was based on personality questionnaires, or “inventories,” and categorized people as having certain traits, like recklessness or restraint, at levels that were fairly stable over time.

Neither model was particularly predictive of what people actually did in experiments, Mr. Mischel concluded, in part because the models ignored context: the specifics of a given situation, who is there, what a person’s goals are, the rewards and risks of acting on impulse.

In a series of experiments at Stanford University beginning in the 1960s, he led a research team that presented preschool-age children with treats – pretzels, cookies, a marshmallow – and instructed them to wait before indulging themselves. Some of the children received strategies from the researchers, such as covering their eyes or re-imagining the treat as something else; others were left to their own devices.

The studies found that in all conditions, some youngsters were far better than others at deploying the strategies – or devising their own – and that this ability seemed to persist at later ages. And context mattered: Children given reason to distrust the researchers tended to grab the treats earlier.

The experiments did not seem seminal at the time, at least on their own. But in a 1973 paper, Mr. Mischel assembled them with a raft of other evidence to level a sharp critique of standard, trait-based personality psychology.

“The proposed approach to personality psychology,” he concluded, “recognizes that a person’s behavior changes the situations of his life as well as being changed by them.”

In other words, categorizing people as a collection of traits was too crude to reliably predict behaviour, or capture who they are. Mr. Mischel proposed an “If ... then” approach to assessing personality, in which a person’s instincts and makeup interact with what’s happening moment to moment, as in: ‘If that waiter ignores me one more time, I’m talking to the manager' or: ‘If I can make my case in a small group, I’ll do it then, rather than in front of the whole class.’ "

In an era when traditional ideas were on trial across the culture, the paper had the impact of a manifesto. Many in the trait-psychology camp reacted with anger, accusing Mr. Mischel of trying to tear down the field. On the other side, many scholars were delighted: Social psychology, the study of how situations shape behaviour, had a new champion.

“For us in the field, that paper was perhaps his biggest contribution,” Brent Roberts, a professor of psychology at the University of Illinois, said.

For the wider public, it would be the marshmallow test. In the late 1980s, decades after the first experiments were done, Mr. Mischel and two co-authors followed up with about 100 parents whose children had participated in the original studies. They found a striking, if preliminary, correlation: The preschoolers who could put off eating the treat tended to have higher SAT scores, and were better adjusted emotionally on some measures, than those who had given in quickly to temptation.

The paper was cautious in its conclusions, and acknowledged numerous flaws, including a small sample size. No matter. It was widely reported, and a staple of popular psychology writing was born: If Junior can hold off eating a marshmallow for 15 minutes in preschool, then he or she is headed for the dean’s list.

“It had a life of its own and grew into an urban myth of sorts,” Yuichi Shoda, a professor of psychology at the University of Washington and a co-author of the paper, said. “It’s like surveying 50 people and saying you can predict a national election based on that.”

In 2014, Mr. Mischel published his own account of the experiment and its reception, The Marshmallow Test: Mastering Self-Control.

In at least one serious replication attempt, scientists failed to find the same results. Still, there is general agreement that self-discipline, persistence, grit – call it what you like – is a good predictor of success in many areas of life.

“Dr. Mischel was one of the central pillars of the entire personality field for the last 50 years,” Mr. Roberts said.

Walter Mischel was born on Feb. 22, 1930, in Vienna, the second of two sons of Salomon Mischel, a businessman, and Lola Lea (Schreck) Mischel, who ran the household. The family fled the Nazis in 1938 and, after stops in London and Los Angeles, settled in Brooklyn in 1940.

After graduating from New Utrecht High School as valedictorian, Mr. Mischel completed a bachelor’s degree in psychology at New York University and, in 1956, a PhD from Ohio State University.

He joined the Harvard faculty in 1962, at a time of growing political and intellectual dissent.

Moving to Palo Alto, Calif., in 1977, he joined Albert Bandura, Gordon Bower, Ellen Markman, Philip Zimbardo and many other psychologists in what became a golden era at Stanford University, in which the unstated goal was to shake up the field of psychology.

Mr. Mischel joined the Columbia University faculty in 1983. He became the chairman of the psychology department and continued to collaborate widely with other researchers, many of them former students. He eventually achieved emeritus status.

“I am glad that at the choice point at 18 I resisted going into my uncle’s umbrella business,” he wrote in the autobiographical essay. “The route I did choose, or stumbled into, still leaves me eager early each morning to get to work in directions I could not have imagined at the start, wishing only for more time, and not wanting to spend too much of it looking back.”

In addition to Ms. Eisner, Mr. Mischel leaves two other daughters, Judith and Rebecca Mischel; six grandchildren; and his partner, Michele Myers.