His daughter Julie Morrisett confirmed his death but did not cite a cause.
Millions of children have grown up watching “Sesame Street” since it debuted on public television Nov. 10, 1969, making international celebrities in the years that followed of the Muppets that puppeteer Jim Henson created for the show. “Sesame Street” also featured a racially diverse cast of live actors who interacted with the puppets, talking through matters from shoe-tying technique to the meaning of death.
Compared with the colossal yellow Big Bird, the ravenously hungry Cookie Monster or the trash-can denizen Oscar the Grouch, Dr. Morrisett kept a low profile. A Yale-trained psychologist who served as vice president of the philanthropic Carnegie Corp., Dr. Morrisett was — at least to the children who watched “Sesame Street” — an unseen but central force in the show.
In a statement posted on Facebook by the Sesame Workshop, the organization Dr. Morrisett founded in 1968 with Cooney as the Children’s Television Workshop, Cooney said that “without Lloyd Morrisett, there would be no Sesame Street.” He was the one, she said, who “came up with the notion of using television to teach preschoolers basic skills, such as letters and numbers.”
Dr. Morrisett recounted that the idea came to him early one Sunday in 1965, when he awoke to discover his 3-year-old daughter Sarah in front of the television set, eagerly awaiting the start of the morning cartoons. She was entranced, even hypnotized, by the test signal filling the air before her show began.
“It struck me there was something fascinating to Sarah about television,” the author Michael Davis quoted Dr. Morrisett as saying in the book “Street Gang: The Complete History of Sesame Street.” “What is a child doing watching the station identification signal? What does this mean?”
Not long after, Dr. Morrisett attended a dinner party at the home of Cooney, a producer of educational television. “Do you think television could be used to teach young children?” he asked her, according to Davis’s account.
“I don’t know,” Cooney said, “but I’d like to talk about it.”
They made a formidable pair. While Cooney prepared a report for the Carnegie Corp. — “The Potential Uses of Television in Preschool Education” — that would form the philosophical foundation of their show, Dr. Morrisett went about securing grants from his own organization, as well as the federal government, the Corporation for Public Broadcasting and the Ford Foundation.
Cooney’s report noted that “more households have televisions than bathtubs, telephones, vacuum cleaners, toasters, or a regular daily newspaper.” By harnessing the medium of television, she and Dr. Morrisett argued, an educational program could help millions of children across the United States who were entering school with little or no preparation.
Of particular concern were disadvantaged children in urban areas and other marginalized communities who, Dr. Morrisett had seen through his work at the Carnegie Corp., were particularly difficult to reach.
“We found that those children would enter school three months behind and by the end of first grade, be a year behind,” Dr. Morrisett told NPR years later. “I wondered whether television could be used to help children with school.”
The show was rigorously research-based, with psychologists and other experts on staff to help shape the show’s material and the manner in which it was presented. The show was replete with jingles and rhymes, stories and fun, all to teach children in such a way that they hardly noticed they were learning.
“Sesame Street” became a mainstay of public television and, over the last 53 years, the longest-running children’s program on U.S. television. Dr. Morrisett served as chairman of the workshop from 1968 until 2000.
“The goal,” he said, “was to have children entering school prepared to succeed.”
Lloyd N. Morrisett — the middle initial stood for nothing — was born in Oklahoma City on Nov. 2, 1929. He grew up in Yonkers, N.Y., where his father was an assistant superintendent of schools, and later in Los Angeles, where he became a professor at UCLA. Dr. Morrisett’s mother was a homemaker.
Dr. Morrisett received a bachelor’s degree in philosophy from Oberlin College in Ohio in 1951 and a PhD in psychology from Yale University in 1956. He taught at the University of California at Berkeley before moving to New York to work at the Social Science Research Council and then the Carnegie Corp.
From 1969 to 1998, Dr. Morrisett was president of the nonprofit Markle Foundation, where he used its endowment to support educational uses of television and other media. He was a past board chairman of the Rand Corp.
Dr. Morrisett’s survivors include his wife of 70 years, the former Mary Pierre, of San Diego; two daughters, Sarah Morrisett Otley of Farmington, Maine, and Julie Morrisett of Oakland, Calif.; and two grandchildren.
In 2019, “Sesame Street” became the first television program to receive the Kennedy Center Honors. Along with Cooney, Dr. Morrisett accepted the recognition, in the company of a Muppet retinue of Elmo, Abby Cadabby and, of course, Big Bird.
