LIKE EISENHOWER or a kid in the Haight-Ashbury, Didion is achingly inarticulate. She is, she says, suspicious of the spoken word. "You interview somebody who is a public figure, and the answers you get, they're set answers. You've heard them before. You've read them before," Didion says. "And when you're interviewing somebody who isn't a public figure, they don't know what they think that much. I mean, I think, people reveal themselves in other ways."

Right. Joan Didion paints her toe-nails red. Small, slight, a native Californian - the palest southern Californian I have ever met - she speaks tonelessly, too softly, in fragmentary sentences. It has become a family joke: "John said yesterday" - that's her husband John Gregory Dunne who is writing a movie in the room next door - "John said yesterday that I should have a brain scan, I finish so few sentences." But the Chekhovian detail is her jacket. A raw silk jacket. Costly and exquisitely cut. She bought it a couple of years ago in Honolulu, and one of the darts has come loose, she says; she meant to have it repaired. She loves this jacket.

In The Book of Common Prayer - which clung to the 1977 best-seller list for 15 weeks and got the critics' imprimatur - Didion refers more than once to her heroine's $600 handbag, which has a broken clasp. The handbag becomes an emblem of character, its "just perceptible disrepair" betraying "some equivalent disrepair of the morale, some vulnerability, or abandon."

Home in Los Angeles, Didion drives a yellow Corvette, a 1968. In Play It As It Lays , Maria roams the highways in a Corvette. That year, 1968, Didion regards as something of a national nadir. It is also the year she came of age professionally. Slouching Towards Bethlehem , her first collection of magazine pieces, the direct progenitor of The White Album appeared. Sixty-eight was also the year of the Beatles' "white album," in which they opted out of the "revolution." Didion hates that record a lot. "Maybe it was because it got all mixed up with the Manson trial. But it seems to me that I thought it was ugly before that. Ugly songs you know, just sort of ugly songs. The music and the lyrics."

Unromantic?

"Just ugly. Harsh. It gives me a headache." The record, as Didion sees it, represents the decade - and the word "album" suited a collection. "In a way the long piece" - the title piece of The White Album - "is about this period of time when the narrative seemed to break down."

Things stopped making sense, morally, psychologically.Mothers left their five-year-olds in the middle of the freeway to die. Joan Didion picked out the dress Linda Kasabian would wear on the first day of her testimony about the murders at Sharon Tate's house.

"And after that, I never looked for the narrative," Didion says slowly, so softly it is hard to hear. "I mean I really haven't since the '60s been looking for narrative. If the narrative's not there, if it doesn't present itself, it doesn't bother me as much as it used to."

What does bother her?

"I try not to analyze," Didion says. "I don't analyze. I'm so nervous about not being able to work, about losing interest." In 1966, when her adopted daughter was born, Didion had a writing block for nearly a year - "I try to keep as much under water as I can."

Except when she's writing, which she does every day, all day. But no thinking beforehand. Part of what Mark Schorer, with whom she studied at Berkeley a quarter of a century ago, meant by "technique as discovery." Commando tactics. She writes consciously - she's obsessed by technique. But she thinks intuitively. I works or it doesn't.

"I think I'm probably deeply conservative. I don't mean I vote conservative," Didion says. "It is a philosophical conviction. I do not necessarily think that change is for the better. Culturally, I am conservative."

Startlingly, for someone who was the prime chronicler of the 1960s, Didion is not really interested in politics. "I believe in a totally laissez-faire world," she says. "Parties, candidates, don't interest me." Indeed, talking politics, she sounds like a child parroting the opinions she has overheard at supper. The opinions of her Sacramento forbears, who came West early enough to speculate in ranch land.

What she is obsessed by is technique, and her prose is swift, sharp, scalpellike - everything her presence is not. She's very interested in the novel she is going to write this year - it will be set in the Pacific, but she can say no more because she doesn't know much more yet. She'll be doing a column for New West , objective pieces, not polemics. "I'm not partisan," she says. "I stand aside from movements" - but it could be said she stands with the main one, the status quo.

California is supposed to be a seismograph of the future. "But I never was a California Golden Girl." Personally, she's worked out a simple narrative: "It's John. It's my child. It's working." The Freudian ideals of love and work.

Didion views the 1960s as a failure. She repudiates the feminist movement, feeling that it has become clogged with trivialities. She has spent much of the '70s writing for movies. Hollywood, Didion says, "is a closed world. That's one of the wonderful things about living there.It's entirely hermetic." As for what is going on now in America - "nothing interesting at all," she says. "It's been very, very quiet. In fact, it's been kind of a quiet time altogether." CAPTION: Picture, Joan Didion by Mary Lloyd Estrin