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In Memoriam - David T. Lykken

David T. Lykken, whose studies of criminal behavior, polygraph testing, and especially the genetics of personality in twins helped undermine some of the most cherished notions of social science, died September 15.

David T. Lykken, whose studies of criminal behavior, polygraph testing, and especially the genetics of personality in twins helped undermine some of the most cherished notions of social science, died September 15 at his home in Minneapolis.

David Thoreson Lykken was born in Minneapolis on June 18, 1928. At 17, he joined the Navy, and he later entered the University of Minnesota on the G.I. Bill.

After graduate work, he became a professor in the department of psychology and psychiatry at the university, where he spent the remainder of his career.

Lykken's wife, Harriet Betts, died last year. He is survived by three sons, Joseph, Batavia, Ill., Jesse, of Minneapolis, and Matthew, of Chicago, and 10 grandchildren.

Lykken's wide-ranging, 50-year career at the University of Minnesota was from the beginning an effort to distinguish the real, fundamental underpinnings of behavior from assumed motives. His graduate dissertation was a study of convicted criminals, showing that those described as "psychopathic" were more impulsive and less fearful than other convicts or noncriminals. These observations, never before documented, laid the groundwork for what is now a flourishing study of psychopathic behavior and its foundations.

Lykken later scrutinized one of the justice system's most widely used measures of intent, the lie detector, or polygraph. In a series of papers analyzing the test, he showed that the machine registered not deception but arousal, which can be the result of many emotional states, including guilt and indignation. Before Congressional committees, and in sometimes sharp debate during court cases, he argued that the polygraph was a flawed instrument and often implicated innocent people. The shortcomings became widely known and led to changes in the laws governing admissible evidence.

Yet Lykken's career became most public in the 1980's, after he began studying adult twins who had been reared apart. He and two University of Minnesota colleagues, Thomas Bouchard and Auke Tellegen, tracked down and reunited more than 130 twins and documented striking similarities in the pairs' behavior and personal quirks. Some had been raised near each other in the same state but in different family environments; others had grown up in different countries. But their shared genetic inheritance trumped vast differences in their upbringing, the researchers found.

Lykken undertook the twin studies, he once said, because "any research one might think of doing with human subjects is likely to be more interesting if you do it with twins."

In a telephone interview on September 12, his co-author, Bouchard, said he had his own reasons for studying twins: "I was convinced some characteristics were heavily influenced by genes but that others were heavily influenced by environment," he said, and he wanted to prove it.

No such luck: the first pair of twins the research team recruited were known as the two Jims, very similar men given the same name by their adoptive families. They both owned a poodle with the same name. Another pair, middle-age women, both had a fear of water that they expressed by wading into an ocean or lake backward, up to their knees, before turning around to swim. A third pair, biological brothers, had grown up to be chiefs of their volunteer fire squads and unwittingly lived close to each other in the same state.

News accounts of the Minnesota Twin Study, as it came to be known, relished these tales of mirrored lives, but Lykken rarely trumpeted the anecdotes himself. He was as rigorous in public as he was in his writing and often turned away invitations to appear on television or to give speeches. He and his colleagues reminded interviewers that no one yet understood how genes could shape parallel lives in such different environments, and that the influence of genes could not be properly understood without further study.