Nature and Causes of Stuttering

There is no single cause of stuttering to date. Many researchers have come out with varied results—some psychological basis and others neurological causes. There is another field that says stuttering is a homogenous disorder but this is yet to be disputed. It says that stutterers suffer from one underlying problem. Nevertheless, popular theories are based on heterogeneity of the disorder.

One theorist has argued that since there no measurement and causes of fluency, it is harder to define the causes of abnormality. For a long time, theorists believed that the concept of stuttering was an outgrowth or exacerbation of normal disfuency. Yet, these premises and models are still subjected to further experiments and studies.

To further aid in the study of stuttering, theorists tried to categorize and make a sub-group of people who stutters. First is the severity as a grouping variable. Many studies used this sub-grouping with so far mixed results of analyses. Meanwhile, the intriguing sub-grouping of Van Riper described four tracks in the development of shuttering.

The model of fluent speech production presents two important points in understanding the categories of stuttering. First, stuttering shows a failure in temporal processing. Second, stuttering shows an imbalance between the capacities of the fluency generating system and demands of the environment.

Following the model of fluent speech production, hypothetical types or sub groups in stuttering are formulated. First, the speech motor control sub-groups which have two distinct groups called dyspraxic stuttering and respiratory control stuttering. The first is characterized by phonological and fluency problems thus causing delays in the appearances of intelligible words and sentences, articulation problems, and slow speech rates.

For example, some adults have the difficulty of pronouncing longer words and have inconsistent articulation errors. Thus, stuttering occurs on longer and unfamiliar words.

The second one is directly linked to difficulties in voluntary control of muscles of respiration. That is why children who stutter most likely have asthma, allergies, and upper respiratory distress. This disorder is characterized by blocks and unvoiced prolongations. 

Some theorists also consider the linguistic processing problems as main etiologic factor. Many children show delayed language development. This general category is called linguistic stuttering. There are three sub-types of group. The first one involves the developmental delays in aspects of linguistic processing. The second one is associated with problems in word finding or retrieval. The third is associated with problems in generation of complex grammatical forms and the last involves problems with auditory processing.

Another sub-group involves the cognitive processes. Problems in this area lead to disfluent speech production. However, one theorist says most likely a person who stutter has cognitive abilities that are superior to their linguistic and speech motor abilities.

Psychologically related factors cannot be eliminated in the sub-groupings of the causes stuttering. Anxiety is an important factor in stuttering. This is a critical factor with respect to severity of stuttering.

Theorists have based these groupings mainly on present results of studies. The sub-groupings of stuttering are yet to be tested and experimented.
