There was such a mix of right brain and left brain in David Joyce Ingle's pursuits that it's fair to say he was of two minds about his accomplishments.
''The duality of the brain becomes a metaphor for my divided life," Dr. Ingle wrote last year for his Harvard class of 1955 record book.
He was a scientist and a storyteller who embraced equally the loneliness of the lab and the limelight of the stage.
''I was somewhat in awe of his perseverance and his singlemindedness -- in more than one direction," said Michael Greenebaum, who was Dr. Ingle's roommate for two years at Harvard.
Dr. Ingle died Jan. 14 at MetroWest Medical Center in Framingham of complications from coronary artery disease and an autoimmune neurological illness. He was 71 and had spent the past year engaged in the arts and his most recent scientific research.
Some friends knew Dr. Ingle as a college professor and researcher in the psychology of vision. Others met Dr. Ingle after his declining motor abilities made laboratory work too difficult, prompting him to focus instead on storytelling, songs, and poetry -- often in performances with his longtime companion, Libby Franck of Framingham.
And many followed him on the bridge he traversed between left brain and right brain. Science friends attended his storytelling performances. When Dr. Ingle began a new vision research project late in life, he recruited volunteers from the artistic community.
Dr. Ingle was born in Rochester, Minn., and exhibited a strong aptitude for science while growing up. He graduated from Harvard with a biochemistry degree.
After college, Dr. Ingle was drafted and took conscientious objector status, according to his sister Jane of Lincoln, R.I. Instead of military service, she said, he worked with a settlement house group in Washington, D.C., helping neighborhood children better their lives, in part by putting on plays. Then he earned a doctorate in biopsychology from the University of Chicago.
In the entry for the 50th reunion of his Harvard class, Dr. Ingle wrote that he was torn ''between completing my Ph.D. in neuroscience or exploring the realm of 'world theater.' However, when I directed a pair of short plays from India and the Philippines, a man from the Voice of America . . . remarked to me in a somber voice, 'You have done more tonight to set back relations between the US and Southeast Asia than anything else this entire year.' Thus reproved, I returned to long days of slicing the brains of small animals."
Dr. Ingle was a National Science Foundation postdoctoral fellow in psychology at the Massachusetts Institute of Technology for two years, then spent 12 years teaching and doing research at Harvard Medical School. He published dozens of articles and chapters on animal behavior and brain functions, edited five books, and organized seven international conferences. He was also a visiting professor at Boston College and Brandeis and Northeastern universities, retiring from full-time work in scientific research in 1992 for health reasons.
His sister said an initial diagnosis was multiple sclerosis, but ''later he used the term autoimmune disease."
''First I learned London music hall songs from Derek Lamb," Dr. Ingle wrote, ''and then I bonded with actress-folklorist Libby Franck, who helped me take my historical and musical interests onto the stage. We spent 10 adventuresome years producing shows for colleges, libraries, historical societies, and a pub or two."
Among the shows were ''Drinking: The Musical," ''The Wit and Woes of Dorothy Parker," and ''Women of the Roaring Twenties."
Dr. Ingle, who was known for performing Scottish folk songs and stories, met Franck in 1994 when he was performing at a Tuesday evening storytelling venue at the former Bookseller Cafe in Cambridge. ''I was just pulled in," she said. ''I was amazed at his depth of knowledge of folklore and ballads."
Ellen Schmidt, a musician and producer of shows, saw the scientist in the storyteller before she knew Dr. Ingle's background. ''I was not familiar with his day job, if you will," Schmidt said.
Still, she was ''always struck by his scholarly approach to whatever it was he was going to present. He would do extremely careful research. Even if he as just coming to an open mike to perform, you knew he was going to bring a tremendous amount of background."
His sister said that ''he's always been a highly focused individual who delves tremendously deeply into anything he delves into."
Gerald E. Schneider, a neuroscience professor at MIT, called Dr. Ingle ''one of the most creative and thoughtful scientists I've ever known."
The two, who met when Dr. Ingle was a postdoctoral fellow at MIT about 40 years ago, collaborated on Dr. Ingle's final research project. Schneider said Dr. Ingle had chanced upon ''a kind of visual short-term memory," in which people look at an image and continue to see it for a few moments after the eyes close. This phenomenon appears rarely, perhaps in 5 percent of the population.
After having set aside scientific research in deference to growing physical limitations, Dr. Ingle was back at it -- albeit in a form he could do sitting down. While on trips for a performance, he would interview people who manifested this characteristic, friends said.
''It does seem to be a window on the brain that we didn't have before," Schneider said of Dr. Ingle's discovery. ''We can say that David opened a new window on the human brain."
In addition to his sister and Franck, Mr. Ingle leaves his mother, Geneva (McGarvey) of Lincoln, R.I.; and another sister, Anne Blandin of Eugene, Ore.
A memorial service will be held in the spring.