"Why must you dwell on all that bad stuff? Why not print (or broadcast) more good news - news about people who do good, happy, constructive things?"

Every journalist has heard those questions and variations on them many times. There are answers, and they are given, but the exchange seldom ends in a meeting of minds. The journalist leaves it feeling that he and his work are hopelessly misunderstood. Members of the public leave it still convinced that news people are hooked on the sensational, the unpleasant and the destructive.

Now a pair of social psychologists have come up with evidence that the people pushing good news may have something. In a series of ingenious experiments, they have found that good news can cause you to feel and act kindly toward your fellow humans and bad news can turn you off so completely that you may become, at least briefly, "socially irresponsible."

The psychologist, Stephen M. Holloway and Harvey A. Hornstein, both college professors, have reported their findings in an article in Psychology Today. (It was reprinted in part in The Post's Jan. 9 Outlook Section.)

Most of their experiments involved exposing subjects to phony radio newscasts, as if by accident. Some subjects heard broadcasts conveying "good" news - a donor responds to an emergency call in behalf of a patient in need, of a kidney transplant, for example. Others heard "bad" news - an aged artist beloved by all is strangled by an aberrant neighbor, for example.

After being exposed to the newscasts the subjects were tested to determine their feelings about other people. The psychologists found that those who had heard good news felt generally favorable toward other people and were willing to cooperate with them. Those who were exposed to bad news took a negative, suspicious view of others and were more inclined to compete with them.

Invariably, they said "the good news produces more favorable views of humanity's general moral disposition than bad news does - despite the fact that the news deals only with the certain special cases and not all with human nature on the grand scale."

One of the most striking evidences of the social effects of news cited by Holloway and Hornstein was this:

In 1968, researchers conducted an esperiment in which wallets were dropped on the street to see how many were returned. Testing had established reliably that about 45 per cent of the wallets would be returned within a few days.

But not a single wallet dropped on June 4, 1968, was returned. Why? Late that night Sirhan Sirhan assassinated Robert F. Kennedy.

Sirhan's bullelt, concluded the psychologists, not only killed a man but "a damaged whatever social bonds had caused people to return those lost wallets. It demoralized people and made them socially irresponsible."

The Holloway-Hornstein findings should not be surprising. We all have felt the despair and discouragements brought on by news of man's inhumanity to man, and most of us would agred that we affect each other by our behavior, good and bad. Nevertheless, is is interesting and useful to have the effects of good and bad news demonstrated.

What does all this mean to the news business? Nobody would suggest that it means all calamitous news should be suppressed. But there may be some who would use the Holloway-Hornstein findings to justify sugar-coating the news - repressing the bad, inflating the good.

Others would say that the press should not repress of inflate but should try to give a more balanced picture of society than it does, with everything - the good and the bad and the in-between - in proper balance.

Both these approaches run contrary to the true role of the press. It is not to paint the world in rosier hues than the facts warrant, although an occasional spot of brightness never does any harm. Nor is it to accurately reflect all the day's happenings that would be impossible. It is, rather, to give the public what it needs to know in order to participate in and help shape society.

The judgments made in fulfilling that role and often less than pure. They are tainted by desires to shock and to entertain, to satisfy an audience, to achieve commercial success. Nevertheless, the basic role is clear.

Holloway and Hornstein decided on the basis of their experiments that "certain news stories can demoralize and estrange us from one another."

They didn't say exactly what that responsibility is. It is certainly is not to tailor the national news diet in order to spread sweetness and light. And suggestion that the media can, or should, create a society of caring, socially responsible citizens is to distort the news function and life itself.

But there is a responsibility, although not a new one. It is the responsibility to recognize that the news business does not operate in a vacuum. News is not only about people, but it affects people.

If the Holloway-Hornstein findings are taken to heart as proof of that, they will be tremendously useful.