Richard B. Wirthlin, President Reagan's personal pollster in the 1980 and 1984 campaigns, has said he will become chairman and chief executive officer of Decision/Making/Information Inc., the polling firm he cofounded in 1969. Replacing Wirthlin as president of the McLean firm is cofounder Vincent J. Breglio, who had served as the firm's executive vice president until 1981. Breglio, who has a PhD in social psychology from Brigham Young University, left the firm to be executive director of the National Republican Senatorial Committee, and later founded another firm, Research/Strategy/Management Inc. Wirthlin holds a PhD in economics from the University of California at Berkeley and taught at several universities before founding D/M/I.

Barry Wright, founder and president of Temporaries Inc., has named D. Geoffrey John to succeed him as president of the Washington-based temporary help company. John spent 19 years with International Business Machines Corp. before joining TI in 1981 as vice president for marketing. Wright, who becomes chairman and chief executive officer, will continue to represent the company in Washington. RETAIL, WHOLESALE TRADE

Dart Group Corp. has appointed two vice presidents with management responsibilities for the drugstore chain and its two affiliate companies, Crown Books Corp. and Trak Auto Corp. Robert F. Ampula, formerly director of data processing for Giant Foods Inc., has joined the firm as vice president for information services. And William E. Bolton, previously vice president at Dart Drug, has been named vice president for loss prevention at the Landover-based corporation. Also, Carol Schofield and Taner Kiranbay, both former managers of Trak Auto Corp., have been promoted to directors of advertising and distribution, respectively.

The Computer Store Inc. has named Jack Barse, formerly manager of its McLean outlet, to southern regional manager of the East Coast computer retail chain. Barse, who will be based in Washington, replaces Marc Gevinson, who has been appointed vice president for corporate development at the firm's Sudbury, Mass., headquarters. Bill Dobson has been named the new manager of the McLean store. And Bruce Burroughs will head the newest outlet, slated to open this month in Alexandria. The region's commercial sales force will be managed by Bud Beal.

Earthworks Inc. has appointed William T. White III vice president for retail operations at the Washington tobacco and pipe retailer. White joined the store three years ago as a salesman.