Is Congress suffering from collective tension? What motivates political terrorists? are other cults heading for Jonestown-type suicides?

Reams of quickly-written government reports and press accounts have been written about these questions. But now an emerging group of scholars - they call themselves political psychologist - are searching for scientific answers.

The group, the International Society of Political Psychology, tonight ends a three-day conference at the Washington Hilton. More than 500 government officials and scholars-psychologists, psychiatrists, political scientists, sociologists and anthropologists-attended.

Founder Jeanne N. Knutson, holder of doctorates in psychology and political science, said she organized the group two years ago because she and "a lot of other people were frustrated with the work being done in political psychology."

The result so far is an international membership of more than 1,000, two conference and a forthcoming journal.

Now, says Knutson, it's time to make a dent in the hard psychological questions affecting public policy.

And many of them are personal. Former representative Charles W. Whalen Jr. of Ohio who spoke at a panel on congressional tension, told of the pressures of family, job, tenure and health which add up to a heavy burden for congressmen. Heavier than those faced by businessmen or doctors? Yes, Whalen asserted, because of the constant round of social obligations.

"This means I would leave home at 7:15 in the morning and many times not get back until 10 o'clock at night," said Whalen, who served in Congress from 1966 to 1979. "There'd be many days I wouldn't see my children."

Whalen said there were many times he failed to meet his wife for theater or dinner engagements because of congressional commitments.

"I've changed clothes in the back seat of my car many times just so that I could go on and make another appointment," he said. "And the pressure is growing. The roll calls in Congress have jumped from 177 in 1969 to 942 in 1978." (Two current congressman canceled their talks before the same panel to attend a roll call.)

Congressmen, Whalen says, suffer the tension of making 800 decisions every year, of constantly pitting their political ideas directly against an opponent's and worrying about re-election every two years.

"Why did I stay six terms," he asked rhetorically. "It's a good job. And we're hams. Most of us were like the cast of 'Aida' - you get a solo occasionally."

But at some point, Whalen said, diminishing utility set in and "the emotional costs outweigh the benefits." Congress, he contended, is out of control because its members are under too much pressure.

At a panel on 20th-century leaders and assassins, political scientist James W. Clarke listed five basic personality types for assassins: psychotics, neurotics, zealots and ideologues, nihilists and contract killers. James Earl Ray, the convicted murderer of Martin Luther King Jr., he said, did not fit into any of these categories.

But Ray's biographer, George McMillan, Retorted that Ray indeed manifested strong political passions and a hatred for blacks. "He would've killed King sooner if he'd been out of jail," contended McMillan.

As a youth, McMillan said, Ray admired Hitler and took the loner's course as the only republican among his friends in rural eastern Missouri. He read Ayn Rand, once talked of killing President Eisenhower and was deeply interest in the McCarthy hearing of the 1950s.

In an address on cults, psychologist Margaret Singer said that in interviews with 30 survivors of the Jonestown mass suicide, the cultists said People's Temple leader Jim Jones would gather information on people after they visited the temple and filled out a card giving their home address.

Temple members, said Singer, a professor at the University of California, would rifle garbage cans to find out what foods people ate or what personal effects they were discarding. Temple emissaries would also visit prospective members, make an excuse to go to the bathroom and search the medicine cabinet.

Jones would then get up during a service, the psychologist explained, "and say, 'I feel the presence of someone in the congregation who had diabetes and she is under the care of Dr. Johnson.' Of course there'd be a great shaking and ruffling in the area where that person sat."

After tonight the academic group will begin gearing up for the next year's meeting in Boston. There'll be more papers and panel discussions.

But will their activites affect public policy? Knutson says maybe, in a ripple effect. "We're not an advocacy group, she explains. "Our primary aim is to understand these problems as scholars. We're trying to look at problems that haven't been examined scientifically." CAPTION: Picture, Jeanne N. Knutson; By Harry Naltchayan - The Washington Post