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

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

Dr. 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 Dr. Mischel’s deepening frustration with the predominant personality models of the mid-20th century.

One model, rooted in Freudian thinking, saw people as prisms of unconscious, often conflicting desires. The other, based on personality questionnaires, or “inventories,” 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, Dr. 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.