The weight of words: childhood memories of a literary innovator; Childhood, by Nathalid Sarraute. Translated from the French by Barbara Wright. New York: George Braziller Inc.256 pp. $14.95.

What is it like inside the mind of an acutely intelligent, sensitive, and unhappy eight-year-old? In 1908, Nathalie Sarraute, who would later become one of this century's most influential French novelists, was such a child. In her newest work, ''Childhood,'' translated by Barbara Wright in consultaton with the author, Sarraute recalls the indelible moments, thoughts, and feelings of her earliest awareness.

Nathalie Sarraute was born in Ivanovo, Russia, in 1900 to members of the well-to-do Russian-Jewish intelligentsia. When she was 2, her parents were divorced. After a few years of being shunted between her mother in St. Petersburg and her father in Paris, she was sent at 7 or 8 to live permanently with her father and stepmother in the French capital.

Since ''Tropismes'' (her collection of ''prose poems'') made literary waves in 1939, Nathalie Sarraute has been at the forefront of a movement known in France as Le Nouveau Roman, the New Novel. This form can be regarded as a younger cousin of the stream-of-consciousness works of Marcel Proust and the contemplative dissections of experience of Jean-Paul Sartre. Unlike linear fiction, the nouveau roman does not concern itself with plot, character development, or psychologically descriptive narrative. Rather, it seeks to probe , distill, and understand experience through minutely described but fragmentary incidents, objects, or sensations.

Although far more frankly personal than her other works, ''Childhood'' clearly belongs with its siblings in the nouveau roman genre. Like many of them, it is written as one long conversation, this time between Sarraute and another, more critical, distanced, yet searching self, who urges her on to explore the intense, painful, and revelatory inner life of the child she once was.

It is not so much the quantity of the incidents she recalls that is extraordinary, but rather their quality, in the graphic explicitness of her own dissected emotions.

One of the most fascinating insights of this book, and one that was to characterize her whole life, is Sarraute's relationship to what she calls ''the weight of words.'' Living in St. Petersburg with her mother and stepfather at ages 6 and 7, she matter-of-factly describes herself as the terrified, helpless victim of the ''ideas'' that would occur to her, and against whose mysterious power she received no loving, motherly protection whatever.

The ''idea'' might be that her doll was more beautiful than her mother, that her mother's skin looked like a monkey's, or that her mother was tightfisted with the servants. When Natasha, out of a passionate sense of loyalty, confided these ''ideas'' to her mother, the scorn and coldness with which they were received left her utterly alone and incapable of dealing with the pain and confusion she felt.

Then, having undergone the wrenching separation from her mother on being sent to Paris to live with her father at about age 8, Sarraute describes the impact on her of a servant's passing remark: ''What a tragedy, though, to have no mother.''

'' 'What a tragedy!' ... the word strikes you, it strikes you like a whiplash. ... I remain motionless for some time, hunched up on the edge of my bed. ... And then, everything in me revolts, rises up, with all my strength I reject it, I smash it, I tear off this yoke, this carapace. I won't stay in this thing in which this woman has imprisoned me....''

With almost no external aid, Natasha is beginning to emerge from the childish helplessness that had held her in its grip. With exhilaration she expresses the freedom she is gaining over the power of the frightening ''ideas'' that used to occur to her: ''How clear my mind seems now, how clean, flexible, healthy. ... Ideas ... not 'my' ideas ... ideas, like everyone else has, occur to me as they do to everyone else. I can think of anything whatsoever without being afraid.''

Natasha's triumph over her emotional imprisonment is truly realized when she starts to go to school and her lifelong love affair with words can get under way. Although she still has painful encounters with her stepmother and experiences a final proof of her mother's lack of love for her, she is becoming a person with a life of her own, passionately driven by her desire to learn, to excel, to write.

In describing the joy she was discovering in her new school life, she reveals the independent thinker Nathalie Sarraute would become, even though she is speaking as a nine-year-old writing a dictation in class: ''I am nothing other than what I have written. ... Here, I am in security. ... Everything that happens to me here can only depend on me.''

As devastating as are many of the incidents in this book, its ultimate effect is one of exhilaration and triumph. Even for those who have never read, or will never read, Nathalie Sarraute's nouveaux romans, this is a fascinating and profound exploration of childhood.