DES MOINES, JULY 2 -- Richard A. Gephardt, Paul Simon and Michael S. Dukakis scored well with a group of Iowa Democratic activists who gave a computer their instantaneous reactions as they watched the first televised "debate" among their party's presidential candidates Wednesday night.

The clear loser here in this group -- and among top political consultants interviewed by The Washington Post -- was former Arizona governor Bruce Babbitt, who has pinned almost all his hopes on the Iowa caucuses with which the nomination battle will start next February.

Several consultants in both parties said they were impressed with Sens. Albert Gore Jr. and Joseph R. Biden Jr., but the two got middling ratings from the 85 Iowans who participated in the computer-aided laboratory experiment here. Jesse L. Jackson, the seventh candidate in the round-table session televised from Houston on Public Broadcasting System stations, drew mixed reviews from the experts and lost some ground with the Iowans.

Before-and-after judgments of the all-Democratic "jury" here showed strongly positive reactions to three men: Gephardt, who has campaigned tirelessly in Iowa, strengthened his first-place status. A predebate sampling of the group showed him the choice of 19 percent. After the debate, he had 27 percent.

Simon, the Illinois senator, made the biggest gains in personal ratings, and his presidential support doubled. Dukakis, the governor of Massachusetts, received the best marks for the debate and had 14 percent of the presidential support, with Simon, Biden and Gore tied at 12 percent each.

The unprecedentedly early Houston forum, less a debate than a two-hour quiz program in which the seven Democrats responded to generally antagonistic questions from commentator William F. Buckley Jr. and soft queries from former Democratic national chairman Robert S. Strauss, drew little blood.

But Republican strategists who watched generally said that the Democratic field, dismissed by some as "the seven dwarfs," included several contenders who could cause the Republicans problems.

Democratic pollster Peter D. Hart said, "I tried to imagine them face to face with George Bush or {Senate Minority Leader} Bob Dole, and I thought, 'Almost any of them would do just fine.' "

Hart said he was "worried" that on foreign policy, the Democrats were so eager to condemn President Reagan's policies that they neglected to emphasize "what Democrats believe in and would defend."

But the partisan audience here, equipped with computerized hand levers with which they could register their approval or disapproval of what they were seeing and hearing from Houston, electronically cheered every time one of the contenders took a tough poke at Reagan's economic policies, the "Star Wars" Strategic Defense Initiative or aid to the contra forces fighting in Nicaragua.

Among the reactions from consultants and Iowans:Babbitt: He lost seven of the eight Iowans who said before the debate he was their presidential choice, and he had by far the worst ratio of positive to negative comments on his performance during the debate.

His head-bobbing drew criticism from most of the consultants, with Republican John P. Sears saying, "He just didn't look right. He moved around a lot and he had a sour look on his face." Biden: The Delaware senator did not register strongly with the Iowa audience and left few minds changed. Several of the consultants, however, were impressed with his potential. Republican media adviser John Deardourff called him "the most telegenic . . . relaxed, reasonably warm, friendly and intelligent."

But Richard Wirthlin, who polls for Reagan, said Biden appeared "almost too laid-back, as if he were trying to wipe out the picture of the table-pounding he did at those televised Senate hearings." Dukakis: While well behind Gephardt in presidential preference, late-starter Dukakis was rated tops by the Iowans as being a strong leader, having good ideas and being persuasive, and was tied with Simon for tops in intelligence.

Many of the consultants liked what they saw of him, too. Wirthlin rated Dukakis the highest, saying he showed "a good mix of fire and ice." Republican Vince Breglio said, "He showed the toughness people demand in a president, and his talk about his family embodying the American dream carries a powerful message of hope for the future."

Deardourff, on the other hand, said Dukakis "appeared anything but warm, and his attempts at humor were pretty pathetic." Gephardt: The debate reinforced already positive feelings among the Iowans about Gephardt, especially his persuasiveness. He drew more mixed reviews from the consultants. Deardourff found him "well-organized, crisp and always aware of the camera." William Sweeney, a Democratic consultant, said, "He was well-prepared and made no mistakes." On the other hand, Breglio said the Missouri lawmaker was "too intense, too slashing" and Sears said, "He has no off-speed pitch." Gore: The young senator from Tennessee impressed some of the consultants more than he impressed the Iowans, who rated him sixth in almost all respects, including his debate performance.

Texas Democratic consultant George Christian said Gore looked "young and vigorous and may have gained more than any of the others." Texas Republican pollster V. Lance Tarrance was impressed not only by his "Christopher Reeves good looks" but by the impression that Gore "was the only one who tried to show he's a centrist."

Sears rated Gore the best, citing "a good combination of sincerity and common sense. He clearly showed he can play in this league, despite his youth."

Wirthlin said that "if looks elect a president, he'll win," but said his manner was "too wooden, too prepared." Eddie Williams, director of the Joint Center for Political Studies, and Breglio commented independently that Gore needed only a pair of glasses to make himself a Clark Kent clone. Jackson: The only black and the only one in the field with previous presidential campaign experience lost ground with the overwhelmingly white Iowans, dropping from 9 to 5 percent in the presidential preference poll. Williams said Jackson "seemed subdued, as if he were trying to be political, not emotional." Deardourff said, "He was out of his best atmosphere. He deliberately went into a shell." Simon: The Illinoisan's populism was a big hit here, with quantum jumps and high ratings for experience, qualifications, intelligence and being "close to you on the issues." He also leapt to the top of the list in "understanding Iowa's problems." Among the outside observers, Williams commented on "the sincerity and strength of convictions . . . the sense of decency" Simon conveyed. Republican Breglio said, "It was like watching 'The Revenge of the Nerds,' " but warned that those who judged Simon solely by his appearance would probably "be turned off."

Republican Paul Wilson said Simon came across as "a country teacher, not really engaged or aggressive." Tarrance said, "He may have the highest IQ, but he's never going to photograph well . . . . His earlobes are unbelievable." And Democrat Christian said Simon "does not project the vigor and youthfulness" of the rest of the members of the Democratic field.

The panel interview here was arranged by Washington pollsters Harrison Hickman and Paul Maslin, using technology supplied by the Seattle firm of Wheeler and Associates. The cost of the project -- which the sponsors would not disclose -- was raised by William W. Batoff, a Philadelphia businessman and Democratic donor who is without a candidate since Gary Hart's withdrawal.

Batoff said he was impressed, as Maslin was, by the response to Simon but said he would not be influenced by it. The pollsters cautioned that other forums and face-to-face campaigning would eventually be much more important in Iowa Democrats' decision.Staff writer Thomas B. Edsall contributed to this report.