Decision/Making/Information Inc., a political research and polling firm, has appointed Thomas B. Hughes president and William K. Tripp vice president of its marketing research division. Hughes joined the firm in 1983 as senior vice president. Tripp was with Opinion Research Corp. of Princeton, N.J.

The Interface Group Ltd., an executive placement firm, has appointed Eliza M. Goodhart a research associate. She was previously a trainee at the Irving Trust Co. in New York.

McManis Associates Inc., an international management and research consulting firm based in Washington, has appointed four new vice presidents: Loretta Glaze Elliott, a former executive with the Arkansas Department of Finance and Administration; Susan V. Nelle, previously financial management advisor for E. F. Hutton & Co.; Louis Pavia Jr., a senior associate of McManis since 1978, and Jerrie A. Stewart, a senior associate since 1974.

Projection Inc., an audio visual equipment rental firm in Arlington, has named Joe Loftus a director of sales with responsibility for national accounts. He was formerly sales director for McCune Audio Visual in San Francisco.

Raymond E. Lovett, a psychotherapist and freelance writer for Sports Illustrated, The Smithsonian and The Washington Post, has opened a psychotherapy practice on Pennsylvania Avenue NW.

William R. Hamilton & Staff, a political polling and market research firm in Chevy Chase, has named two new senior partners: Greg Schneiders, a former deputy assistant to President Jimmy Carter, and Keith Frederick, a Hamilton vice president.

The law firm of Arter & Hadden has named James A. Laurenson, formerly chairman of the Nuclear Regulatory Commission's Atomic Safety and Licensing Board, as a partner in its Washington office. Janice F. Hill, a former associate chief counsel at the National Telecommunications and Information Administration, has joined the firm as a counsel.