Do the imagemakers distort democracy?

As another American presidential campaign winds down, the time may be right for a bit of historical perspective on the perplexing process by which we've come to choose our chief executives. Katherine Hall Jamieson, a professor of communication at the University of Maryland, is primed to provide it.

Dr. Jamieson's just-published book, ''Packaging the Presidency: a History and Criticism of Presidential Campaign Advertising'' (Oxford University Press), is a varied, sometimes fascinating mass of historical anecdote arranged to provide a chronology of presidential campaigning in the television age.

Over breakfast at a downtown Boston hotel recently, she shared some observations on the evolution of presidential campaigning generally and on the Reagan-Mondale campaign in particular. Discussion revolved around the central question: To what extent is advertising distorting the political process, giving us candidates who are more the creations of their ''media men'' than of their own thoughtful wrestling with issues?

In doing research for her book, Jamieson looked for presidential campaign ads that, in her words, ''demonstrate advertising's fundamental distortion of the political system.'' Her finding? ''They're just not there.''

That doesn't mean distortion has been wholly absent. She did come across such highly suspect items as the 1960 John Kennedy ads that used clips from his debates with Richard Nixon. The ads showed Nixon nodding as if in agreement with what his opponent was saying, an effect created by editing the film excerpts together out of sequence from what actually transpired in the debate, says Jamieson. Hardly a gross distortion, but damaging to Nixon. The Republicans raised a fuss, but the press didn't bother to compare the ads to the debate itself - a journalistic lapse that wouldn't have occurred a decade later, Jamieson contends.

What spurred journalistic interest? Most important, she says, Joe McGinniss wrote ''The Selling of the President.'' That 1969 book, based on McGinniss's firsthand observation of Nixon campaign strategy sessions in 1968, was the ''turning point in press awareness of campaign advertising,'' says Dr. Jamieson.

But McGinniss's central point - that campaign advertising can grossly distort the public's perception of a presidential candidate - is false, according to Jamieson. ''Ads just build on and digest material already in the campaign,'' she argues. And the inclusion of professional advertising techniques in political campaigns - so shocking to McGinniss - was something that predated his book by nearly two decades, she says, going back to Eisenhower's 1952 campaign.

Political imagemaking itself goes back much farther. In her book, Dr. Jamieson at one point sketches William Henry Harrison's 1840 run for the White House. His imagemakers successfully put across their wealthy and ailing candidate as a rough and ready frontiersman, a true man of the people.

A fundamental thing to remember about political imagemaking, says the very straight-talking Jamieson, is that ''it's an art, not a science.'' The consultants who sign on to perform media magic for politicians are eminently fallible, she points out. ''More often than not, these people shoot their candidates in the foot.''

Any wounded feet this political year? Plenty on both sides, she says. Reagan's ''feeling good about America'' ads have left him ''vulnerable to the charge that it's a Pollyanna-ish approach that denies there are problems yet to be addressed.'' Such rosy repetitions might work for Pepsi-Cola, she says, but they can undermine credibility in a political campaign.

And the challenger? ''It could have been a close campaign had Mondale played it right,'' says Jamieson. In her analysis, the Democrats made ''an immense advertising blunder'' by not following up quickly on Mondale's well-received acceptance speech in San Francisco. That speech should have spawned a series of hard-hitting ads, she says. Instead, says Jamieson, the Mondale ad team languished in organizational chaos, missing opportunities to seize the offensive - the late-summer release of an Urban Institute study pointing to increased poverty in the US, for example.

But beyond strategic errors and the rare intentional distortion, Jamieson sees an overall problem with TV ads in a campaign. ''The forms are too short,'' she says. ''What you get is telegraph communication, with little in the way of genuine evidence....'' That failing, she feels, is only partially remedied by debates.

It's true that televised debates raise a whole new set of image issues - who looks good on the screen and who doesn't - but democracy is served nonetheless, she says. ''Viewers have a chance to see tendencies, see habits of mind - what you have to worry about, what you don't have to worry about.''

One last point: While Dr. Jamieson feels gross distortion through misuse of advertising is unlikely in a presidential campaign, she sees little to avert it in local and state politics. At that level, she says, the two main checks on distortion are often missing: tough-minded, persistent press coverage, and built-in restraints on campaign spending.