Definition reprinted with permission from Hood, Stephen B. (editor) available from Stuttering Foundation of America: Stuttering Words (Publication No 2: Speech Foundation of America)
Most researchers and clinicians differentiate between the core featuresof stuttering and the accessory (secondary) features that develop as a means of avoiding and/or escaping from the core features. Core features are generally thought to include the repetition of sounds, syllables and single-syllable words; the vocalized and nonvocalized sound prolongation, and complete stoppages due to tense pauses, hard contacts and silent blocks. In the early developmental stages of stuttering these "core features" are easy, effortless and relaxed: later, however, they coexist with accessory behaviors when they are accompanied by effort, tension, and struggle.