A latent trait approach to the development of persistent stuttering.
The premise that stuttering disorders develop according to the orthogenetic principle, preceding in a continuous, unilinear fashion from a state of relative lack of differentiation to a state of increasing differentiation and hierarchic integration, was examined. Responses to Woolf's Perceptions of Stuttering Inventory of 87 individuals who stutter were analyzed using a Rasch 1980 latent trait model for dichotomously scored data. Analyses of responses indicated struggle, avoidance, and expectation through the development of stuttering that became increasingly articulated, integrated, stable, and yet responsive to environmental changes. Four stages of development were noted: Stage I was characterized by the expectation of interruptions in the flow of speech, the addition of unnecessary sounds, and general body tension. Stage II was typified by distinctions between troublesome and not so troublesome words and sounds and between the speaker and various audiences and contexts for speaking. In Stage III, speech control decreased despite more focused and complex efforts to control the environment and the speech apparatus. Stage IV was characterized by automatic scanning of all speech, increasingly uncontrolled body movements, and attempts to produce fluent speech by way of comprehensive changes to sound, rhythm, and pitch. Follow-up of 29 respondents suggested the latent struggle was generally stable over time.