The interior monologue
It is a verbal expression of a psychic phenomenon and it is immediate; this distinguishes it from both the soliloquy and the dramatic monologue, where conventional syntax is respected. It is from introductory expressions like "he thought, he remebered, he said". There are two levels of narration: one external to the character's mind, the other internal. It lacks chronological order and the presence of subjective time. It disregards the rules of punctuation and it lacks formal logical order. It is used in a novel to represent the unspoken activity of the mind before it is ordered in speech. Sometimes interior monologue is confused with the stream of consciousness, but they are different.
Stream of consciousness technique
American psychologist William James coined the phrase "Stream of consciousness" to define the continuous flow of thoughts and sensations that chracterize the human mind. As a consequence, the present doesn't exist and the only reality is the individual consciousness where past and future flow into each other. Sigmund Freud discovered the power of the unconcious and led to analyse consciousness more deeply. The French philosopher Henri Bergson distinguished between the mathematical time of science (each minute equals the other) and the time of the mind which changes from one person to another. For example, the time necessary to boil some water is the scientific time, but the time that person waits for the water to boil is the time of spiritual experience; he called this second time "duration". The writers who used this technique were Henry James, James Joyce, William Faulkner, John Dos Passos, J. D. Salinger, Joseph Conrad and Robert Louis Stevenson; the novelist who used this technique were Marcel Proust, Dorothy Richardson and Virginia Woolf.