If you read much of Dan Wegner’s writings on psychology, pretty soon you cannot stop thinking about Dan Wegner, particularly if you try to forget him.

He could have told you that would happen. After all, he wrote a book about the difficulty of suppressing thoughts, and his research showed that the more we try to not think about something, the more likely we are to talk about what we are trying not to think about.

Those studies are detailed in “White Bears and Other Unwanted Thoughts,” his 1989 book on suppression and obsession that would have been a capstone of some careers. For Dr. Wegner, it was simply the tip of the ice floe. Though he taught social psychology at Harvard University, his work had wide application as he examined topics such as conscious will, how torture affects the perception of guilt, and the ways couples and groups decide who has to remember which details.

“Dan Wegner was surely one of the most and maybe the most original psychologist of his generation,” said Daniel Gilbert, the Edgar Pierce professor of psychology at Harvard and a longtime friend of Dr. Wegner.

“Most people in our field try to pick the lock on nature’s door; nature has secrets and we’re trying to get to them,” Gilbert said. “Dan Wegner saw doors where everyone else saw walls. Then he opened them up and showed us the beautiful rooms behind them. He didn’t just give us answers. He gave us questions and then answered them. It was really just remarkable.”

Dr. Wegner, who also was a musician and adept cook, and kept an expansive Groucho Marx nose-and-glasses collection in a display case, died last Friday in his Winchester home of amyotrophic lateral sclerosis. He was 65.

About two decades ago, while teaching at the University of Virginia, he devised an experiment to study secrecy and obsessions. Enlisting college students to play card games at a table, he instructed some to play footsie under the table and tell everyone they were doing so. Others had to keep their footplay secret. One result? “The subjects who made secret contact with their partner were significantly more attracted to their partners,” Dr. Wegner told the Globe in 1994, a finding that, among other things, shed light on the allure of affairs outside relationships.

More recently, he was senior author of a study that examined the impact of search engines, computers, and smartphones on how people retain information.

“Our memories are changing,” he told the Globe in 2011. “So we remember fewer facts and we remember more sources, which website you saw it on or whose e-mail to look in to find that. . . . It’s like having information at our fingertips makes us always go to our fingertips.”

Dr. Wegner “made magic,” Gilbert said. “It would be hard to overestimate the grandeur and impact of his insights. There’s just not another like him.”

The impact of his presence could be as difficult to gauge.

“He was, I would say, a brilliant, extraordinarily creative, and hysterically funny guy,” said his wife, Toni. “He had just the best sense of humor. One of his core values was to be interesting and to say things in clever ways. Really, every day was fun.”

After their first daughter was born, Dr. Wegner had the three of them pose for a birth announcement photo with each wearing a Groucho Marx nose-and-glasses. For their second daughter’s announcement, the Wegners all donned fake arrows through their heads.

Less stodgy than many in Harvard’s professor ranks, Dr. Wegner was 6-foot-3 with the heft of a football lineman. His CD collection seemed beyond counting, and his university webpage included a route, under “useless links,” to electronic music he had created. He was also partial to Hawaiian shirts and only bought a suit three years ago when he received an honorary doctorate from the University of Aberdeen in Scotland.

In conversation he improvised like a musician, taking phrases others spoke and turning them into Robin Williams-caliber riffs that left everyone gasping with laughter.

“Dan was truly the funniest human being I’ve ever known,” Gilbert said. “What John Coltrane was to jazz, Dan Wegner was to conversation. He was deeply, profoundly, truly funny.”

Born in Calgary, Alberta, Daniel M. Wegner was an only child. His father, a Baptist minister, died when Dr. Wegner was a boy. Moving to East Lansing, Mich., he grew up in a home with his mother and maternal grandmother. His mother taught piano, which Dr. Wegner learned to play when he was not up in the attic with his science experiments.

“He got into Yale, but his mom said, ‘Please, please stay here,’ ” his wife said.Continued...