A RANDOM gleanings from the American Psychological Association meeting:

If your package of jellybeans is more than 4 percent purple or white, you're out of luck.

If you live in Cincinnati, "threats" in mail surveys turn you off.

If you live in China you're probably as much of a "social loafer" as if you live in the United States.

And if you've been hanging around the Shoreham or the Sheraton Washington, or either the Capital or Washington Hilton or the Mayflower in the past few days, chances are you're a psychologist.

As a rule, psychologists look a lot like normal people, but you can tell the nearly 14,000 in town this week by drooping shoulders (from carrying the inch-thick program and literally pounds of papers, presentations, forms, brochures and polemics).

The 90th annual convention of the APA is off and running--at the rate of up to 70 seminars, symposia, paper readings, poster presentations and panels per hour from about 8 a.m. to just about 6 p.m. every day this week.

In five different hotels.

With no scheduled breaks for lunch, or for anything else. (Of course there are plenty of unofficial parties, lunches and hospitality rooms.)

One thousand sessions. Four thousand authors, speakers or panelists. Some 900 papers (including the ones on jellybeans, threatening surveys and social loafing . . .). Here it is, ladies and gentlemen, the biggest traveling show-and-tell on Earth. A different city every year. Hotelier's bonanza: 5,000 sleeping rooms reserved seven years ahead . . .

At the center of some of the world's most complicated convention logistics is Candy Won. Her title is Convention Manager. She's not a psychologist herself (and the way she says it suggests she's just as happy that way), but she does all the negotiating with hotels, public transportation systems, shuttle buses, public officials. She assigns rooms, coaxes forms and advance papers out of "the academics," puts together the 300-page program and oversees registration, payments, printing, parking, exhibits--well, actually, everything. She works the convention all year, year after year.

Dress: Anything goes. Laid-back, pony tails and shorts, for both men and women. Preppy Lacostes. Wall Street three-piecers.

High heels disappeared after the first day. (In this week's humidity, even the short walk form the Shoreham to the Sheraton can be a crusher.)

There is a paper entitled "Temperature, Humidity and Violent Crime," by John Cotton of Purdue University. "The data suggest," writes Cotton, "that violent crime does not drop off but increases as temperatures rise."

Most of the heat at the APA meeting was generated by a group of feminist members who distributed angrily worded leaflets attacking the presence of Surgeon General C. Everett Koop, who spoke Tuesday to about 500 delegates. The appointment of the longtime pediatric surgeon to the top public health post was strongly (but unsuccessfully) opposed by feminist, family planning and many other health groups because of his stance against abortion and his widely quoted and controversial worst-possible-scenerio remarks about the kind of world he saw stemming from legalized abortion.

During his speech Koop took time out to counterattack. Much opposition to him, he maintained, was based largely on a speech he delivered "as a satire and a fantasy" because "you get tired making the same speech over and over." He said his remarks had been quoted out of context so that their satirical import was lost. He did not mention his position on abortion but denied that he was anti-woman. During his 36 years of pediatric practice, he said, he trained "more women pediatricians than anyone on Earth."

As surgeon general, he has concentrated his attacks on smoking, drugs and alcohol and has emerged as a strong advocate of behavioral approaches to preventive medicine, although he is still philosophically bemused as to how these approaches can be translated into widespread practice. They require "having people change the way the live," Koop said, "but even the surgeon general knows life doesn't work that way. People have the right to defend themselves from what other people say is good for them."

In terms of public health behavioral projects he:

* Described success in getting TV and movie actors to stop smoking on screen. "It used to be an actor would walk into a room and light a cigarette. Now," Koop said wryly, "he goes over and takes a drink instead . . ."

* Outlined the financial benefit of two behavioral projects, one that would use biofeedback to control incontinence in nursing-home residents and another that would teach elderly women how to sit and stand to avoid broken hips. "People say, 'My mother fell and broke her hip,' " said Koop. "What really happened is his mother broke her hip and then fell." The cost of incontinence, he said, is some $24 billion a year. And the 300,000 broken hips each year could drop to half that "if a woman knew what to sit in and how."

In an earlier symposium a panel of seven psychologists, all women, discussed the "behavioral aspects of gynecology," a first for the APA. Studies and papers presented suggested that:

* Fears of mastectomy kept women from participating in cancer screening programs.

* Low salt diets did not appear to lessen premenstrual syndrome, and large does of Vitamin B-6 in a very small study appeared to have some alleviating affect on menstrual cramps.

Other studies:

* Indicated that "social loafing," the psychological term for the tendency to work harder when you're working alone than in a group, was true in China as well as here.

* Determined that homosexuality was no more abnormal than being left-handed.

*Found that noise in schools from over-flying airplanes could be correlated to lower reading abilities and suggested that too little attention was paid to soundproofing classrooms.

* Discovered that age and attractiveness played the most prominent role in choosing partners at a California videodating firm.

* Made a preliminary determination (from three separate but extremely small studies) that old Mr. Coffee nerves may be a straw man. Moderate amounts of caffeine consumed by pregnant women appeared to produce smaller babies with some abnormal reflexes, but babies who were less irritable than others. Extra caffeine appeared to have a calming, rather than irritating effect on moderate caffeine consumers but irritated those who do not ingest caffeine on a regular basis. And caffeine taken before tests did not appear to impair memory. All preliminary results from minuscule samples.

Jellybeans. E. Mazak Bard, an Akron, Ohio PhD school psychologist, authored the jellybean study. Bard, who "never uses" her first name, writes, "media impact upon consumer food choice may be noted by the unusual amount of interest directed toward the confectionery preference of the President of the United States . . . because of the rising popularity of the jellybean confection, it was felt consumer choice of most preferred and least preferred jellybean might indicate certain variables within the individual's personality structure and perhaps offer insight or future marketing and advertising direction.

"In addition . . . the jellybean preference study was felt to be a unique way of looking at adult personality because of the spontaneous choice and jovial feeling that frequently accompany candy consumption . . ."

Bard emphasizes that jellybeans should not be used alone in diagnoses, but the study nevertheless made these correlations (among others):

Men who choose orange first: Powerful drive toward sensuousness . . . wish to guard against loss of position and status.

Women who choose orange first: High need for security . . . Desire for a relaxed environment in which physical stress is limited.

Men who choose red first: "Eager to enter a relationship stressing satisfaction and attention . . . currently involved in frustrating relationship . . ."

Women who choose red first: ". . . Great personal charm when dealing with others . . ."

Men who choose black first: "Great personal charm when dealing with others . . . Seek to avoid harsh criticism . . ."

Women who choose black first: "Desire recognition and control . . . socially skillful . . . considered persistent."

Men who choose yellow first: want "more power and control over personal future . . . success oriented . . . controlled and analytic."

Women who choose yellow first: want to be regarded as charming individuals . . .considered popular yet overimaginative.

Women who choose purple first tend to be "too trusting."

Well, you get the idea. Astrologers, eat your hearts out.

Oh yes, red and black were the most popular first choices, purple and white the least. As a result, Bard has a serious recommendation to candy makers: purple and white jellybeans should not account for more than 4 percent of each package.

Although the jellybeans in her test were the "Easter basket fat kind," rather than the "Jelly Bellies preferred by the President," Bard said she sent a copy of the study to Reagan and was thanked on his behalf by his secretary. His preferences were "classified." As for Bard, she likes red best.

A few titles:

* Psychological Paradoxes of Strategic Deterrence.

*Stylistic Evolution in Italian Paintings.

* Sado-Masochism Relatedness to the Body and Anorexia Nervosa.

* Women, Borscht, Gays, Laboratory Animals and Nuclear Extinction.

Threatening Surveys: In a study entitled, "Experimentation on Threatening Cover Letter Appeals in a Mail Survey," it was postulated that people who forget to return survey questionnaires they receive in the mail, or who just don't want to, might respond to mild "threats." The letter "threatened" that unless the questionnaire was returned, the person would be bothered by an attempted telephone or personal interview. The result: Threats don't work, at least in Cincinnati, where they were tried. In fact, some people called up and threatened the threateners--that they'd pull out of the survey.

Throughout the week, there was an emphasis on the threat of nuclear holocaust and planetary destruction. The subject was addressed formally through speeches, symposia, films and papers.

The venerable behavioral scientist B.F. Skinner, before an overflow audience in his second major address to the convention, spoke on "Why Are We Not Acting to Save the World?"

He is not optimistic.

He said, " . . . As a general rule, the more remote the future, the less reliable the advice, and, in turn, the less likely we are to follow it and the fewer those who will follow it at all. As to the possible destruction of our world, the brute fact is that, left to advice, only a very few people will act."

Skinner led his colleagues through a series of techniques designed to produce certain behaviors. He described them as insufficient to protect the planet.

"Our only hope," he said, quoting from a paper he prepared two years ago, "is to change the behavior of those, mainly in government, religion or industry and trade, who control the contingencies under which people live . . . The task is difficult because we are offering a kind of advice called a warning . . . People most often respond to warnings simply by disengaging themselves from those who warn them and turning to other things . . . The argument that we have always solved our problems in the past and shall therefore solve this one is like reassuring a dying man by pointing out that he has always recovered from his illnesses. The world may be fatally ill."