All was quiet inside Marc D. Hauser’s Cognitive Evolution Laboratory, perched 10 floors above ground level in Williams James Hall.

The lab, which had been abuzz with activity in past academic years, was dominated by a silence pregnant with lingering uncertainties. On an afternoon late last month, two researchers manned the empty floor as a video camera pointed at a blank wall and an antiquated television set displayed the uneventful scene in black and white. Uneaten dog treats sat on disposable plates scattered throughout the lab.

The place was so quiet, in fact, that it betrayed little of the national frenzy currently surrounding the lab’s steward. Hauser is away.

On Aug. 10, the Boston Globe reported the psychology professor was taking a one-year leave of absence after a three-year internal investigation found evidence of scientific misconduct in his lab. Days later, Faculty of Arts and Sciences Dean Michael D. Smith confirmed that a committee found Hauser “solely responsible” for eight instances of misconduct—three of which were published studies that needed to be retracted or corrected to remove unsupported findings.

The University, Smith said, is cooperating with the Public Health Service Office of Research Integrity, the National Science Foundation Office of Inspector General, and the U.S. Attorney’s Office for the District of Massachusetts.

As Hauser faces federal inquiry, many of his former co-authors, graduate students, and undergraduate advisees struggle to comprehend how the man they knew as a prolific researcher, skilled communicator, and heavyweight in the field of cognitive psychology became enmeshed in scandal. Interviews with these former co-workers paint a picture of a professor who pushed himself and his lab to publish his research at a pace that was impressive—even by Harvard’s standards.

RISE TO THE TOP

When the investigation began in 2007, Hauser had maintained, by all accounts, a hands-on presence in the lab.

Even now, Hauser continues to work on his latest book “Evilicious: Why We Evolved a Taste for Being Bad,” which traces the origins of the human desire to do evil. Even while based in Cape Cod this summer, he managed his lab, and he will continue to lead his lab this year as he spends some time away from campus, researchers say.

When discussing his research, Hauser does not keep his excitement hidden: the man with the thinning gray hair and carefully trimmed goatee bobs his head, furrows his brows, and gestures with his hands to emphasize his points.

He was a distinct presence in the classroom, winning multiple awards for his teaching and gaining the recognition as one of Harvard’s most popular teachers by the senior class in 2001 and 2008. Last year, students gave Hauser a CUE score of 4.93 out of 5 for his ability to “generate enthusiasm” in his 15-person class “Psychology 2381: Hot Topics in Cognitive Science and Neuroscience.” One student said the class was the best at Harvard. Another wrote, “It’s awesome!!!!”

Passionate is one word colleagues use to describe Hauser, who started as an assistant professor in 1992 and rose to the post of associate professor in 1995 and full faculty member in 1998.

Ambitious is another word—but the trait is not necessarily pejorative, according to Psychology Department Chair Susan Carey.

“I would not think there is not a single professor at Harvard who is not ambitious, in the sense of intellectually ambitious,” Carey says. “I would describe myself as ambitious. I am working hard to describe age-old problems, and I think I can make progress.”

Noam Chomsky, an emeritus professor of linguistics at MIT and Hauser’s mentor of more than 15 years, agrees.