Another look upon stuttering

by Ingvar Bergman

Stuttering is known to bring about involuntary and repeated blockings of expressive speech. Unwelcome interference with speech is perceived, which lacks in obvious conscious reason. By will-power the individual attempts to force speech to combat the perceived obstacle. When such forced speech efforts are the main means to defy the unintended blockings, the stuttering will manifest itself. Stuttering will thus emerge as secondary to an underlying primary blocking of speech. There are other ways to view stuttering, but I believe that a notion of a primary blocking of speech readily can be recognised by many stutterers, and that it has important implications for the understanding of stuttering.

Stuttering behaviour occurs in certain social situations, but not in others. The stuttering is generally not constant or stable over time, but variable and dynamic to a high degree. It characteristically shows short and long time variations in its severity. However, the primary blocking of speech seems to be relatively more constant and stable over time, and even more resistant against treatment. Individuals suffering from blocking of speech and stuttering have in general though, despite their difficulties in certain situations and quite paradoxically, an apparent capacity to speak fluently and without speech disruption. It can be demonstrated in particular for more confident emotional expressions, such as curses, imitations, and singing. To explain this paradox it has been proposed a fragility in speech-motor mechanisms for competing activity in the brain, but this idea is far from confirmed in any way. Quite obvious though, as it is implied already in the nature of the paradox, stutterers seem to have a weakened ability to conjure up feelings of confidence in speech.

Research findings

Heredity and environment

There is consensus among the vast majority of biological and medical oriented researchers for a theoretical standpoint assuming that signs of behavioural concordance within identical (monozygotic) twins, as well as behaviours that run in families, give evidence for genetic predisposition. The validity of the theory is seldom questioned and alternative explanations are almost never discussed. That is unfortunate because there certainly are some alternative explanations to consider. One suggests the existence of a social heritage. Another suggests that it can be expected a greater concordance in environmental factors for monozygotic twins than for dizygotic. Scarr (1968, referred in a French study by Misés, Ferrarri and Roubertoux, 1987) has in fact presented evidence showing that parents treat their monozygotic twins alike while they treat their dizygotic twins different. She suggested that these differences in treatment come from an adjustment to the likeness between monozygotic and the difference between dizygotic twins. If this can be shown to be a consistent finding, environmental factors may count for most of the differences in concordance between groups of monozygotic and dizygotic twins, and it's even possible that twin studies in general may not reveal any genetic factors at all. At this moment we don't know, so until more research can clear things out, it is wise to be a little sceptical when authors claim to have found genetic predisposition.

For stuttering, as well as for most other behaviour disturbances, results have been presented that suggest a genetic/biologic predisposition. It has been shown to run in some families, and in a review by Pauls (1990) he found that for monozygotic twins both twins stuttered in 20 of 29 pairs (69%). For dizygotic twins (of the same sex) both twins stuttered in only 3 of 24 pairs (12%). This suggests, according to what has been discussed, that genetic factors may predispose for stuttering, but more doubtless though that environmental factors are responsible for the final release and expression of stuttering. There is no other way to account for the cases of discordance for the disorder in monozygotic twins.

Environmental theories from the first half of the 20th century proposed that stuttering may be caused by distressing environmental conditions:

1. Horrible living conditions. very poor diets.

2. Constant problems within the home.

3. Punitive attitudes and treatments towards the child, evoking fear of speaking because of uncertainty about the responses that may ensue.

Advocates of these, and related, theories generally regarded individuals, before they started to stutter, as having been constitutionally and psychologically no different from normally developing or developed speakers (Ainsworth, 1945, as referred in Hartman, 1994).

Environmental theories of this kind could neither be refuted nor supported since good environmental research in connection with stuttering, as for behavioural disorders in general, on the whole is missing. However, since the twin studies shows that environmental factors undoubtedly play a role in the expression of stuttering, the need for prospective studies of children at risk has been proposed (Pauls, 1990). By following children over time it should be possible to identify potential risk factors associated with the onset and expression of the disorder.

Personality

Between two and five times more males than females stutter (West, 1958; Berry and Eisenson,1956; Van Riper and Emerick, 1984, as referred to in Hartman, 1994). There are no unambiguous empirical evidence for a stutter personality, but the impression is that stutterers are relatively less emotional expressive and more social withdrawn (Bender, 1938, as referred to in Hartman, 1994), they are most often very well adapted in society (Van Riper, 1973, as referred to in Hartman, 1994) and it seems like they are remarkably often engineers (Alm, 1995). The unconfirmed impression points towards a hidden self, where strong feelings tend to have no place: It causes discomfort to "stand out" and get the gazes of others. The self-image is unrealistically diminished, and the expression of the self more prepared for pleasing others than to please one self.

Cerebral activation of right hemisphere during stuttering

Several studies using different methods have reported evidence for what seems like a typical cognitive information processing during stuttering, with cerebral activation of right hemisphere:

Reduced alpha activity indicates increased cerebral activation in EEG measurements. Individuals that stutter have demonstrated reduced alpha activity in right hemisphere at language handling, while non-stutterers normally demonstrate this pattern in left hemisphere (Moore, Craven and Faber, 1982).

Wood, Stump, McKeehan, Sheldon and Proctor (1981) found that cerebral blood flow, another indicator of cerebral activation, increased for right frontal lobe during stuttering speech, and for left frontal lobe during normally articulated speech.

Three different studies suggest transition from right- to left-hemispheric activation along with improved speech fluency (Boberg, Yeudall, Schoplocher and Bo-Lassen, 1983; Moore, 1984; Wood, Stump, McKeehan, Sheldon and Proctor, 1980). Moore (1986) reported a significant correlation between the degree of right-hemispheric activation and the severity of stuttering, so that more severe stuttering shows more right-hemispheric activation.

The meaning of right-hemispheric activation

Right-hemispheric frontal activation as measured with EEG has been found to correlate with negative emotions (Ahern and Schwartz, 1985). Such emotions mean withdrawal and inhibition of emotional expressions and spontaneous behaviour. It can readily be stated then that the typical right-hemispheric activation during stuttering speech can be a consequence of stuttering, but it can also be an interfering activity that directly disturbs spontaneous speech.

Van Riper (1971) observed that the stuttering temporarily disappeared from two stutterers whose right hemisphere was anaesthetised in a so-called Wada test. In another case a man with epilepsy ceased to stutter after a major surgical operation in the right hemisphere (Alm, 1995). This suggests that right-hemispheric activation during stuttering is at least not exclusively a consequence of strong negative emotions caused by stuttering itself, but that it also has importance for the emergence of stuttering.

Right-hemispheric neural activation specifically in amygdala has been associated with unconscious emotional responses, learned on a subliminal (unconscious) level by classical conditioning to aversive stimuli (Morris, Ohman and Dolan, 1998). If the emotional responses were conscious on the other hand, left side of amygdala was activated instead. Moreover, Johnsen and Hugdahl (1993) reported that associative learning of aversive face expressions (by means of classical conditioning to a mild electrical shock), seems to be functionally connected to right cerebral hemisphere. The authors claimed that the result confirmed previous research that showed a right-hemispheric advantage for associative learning. This may in fact imply the possibility that the right-hemispheric activity during stuttering reflects an associative learning, unconscious by nature.

Slower initiation of motor responses

Webster (1993) found that people who stutter have difficulty not only with the initiation of their speech utterances but also with nonspeech sequential motor processes when tested with sequential finger tapping tasks. It is not that the person who stutters is generally slower and/or more poorly co-ordinated than the nonstutterer. The stutterers were in fact significantly slower than the nonstutterers to initiate their responding. Once performance had been initiated, tapping by stutterers was as fast as by nonstutterers. In a similar way stutterers had difficulties to initiate correct writing of sequences of letters. Webster concludes that stuttering is not a speech disorder as such. More specifically, the anomalies associated with stuttering appear to be related to response planning, organisation, and initiation, and possibly to attention mechanisms. Webster proposes the supplementary motor area (SMA) as a locus for interference. As already discussed, the right frontal hemisphere (including SMA) is also a likely locus for interference.

Theory synthesis

Naturally a theory synthesis must include knowledge from development psychology as well as from neuropsychology, biology and genetics. For example, it has been suggested that the differences in sex hormones make boys more vulnerable than girls. An alternative suggestion to explain boys vulnerability can take starting-point in development psychology, where it has been observed that boys in periods relate more actively to their fathers than girls do. It could readily be understood as a developmental need or strategy to build up a masculine identity (Carlberg, 1989). It would be a highly unfavourable circumstance then if the father due to own unresolved difficulties is touchy and unbalanced in a way that may lead to unpredictable and even life-threatening attacks in response to the boy's development strategy. Such circumstances can very well be expected to give emotional memories that automatically slow motor initiation and block speech at slightest resemblance with the original situation. Emotional memories are, as defined by LeDoux (1998), unconscious in contrast to memories of emotions that are conscious, and they are mediated by other neural networks in the brain than conscious memories.

It remains to evaluate the significance for development hypothesis like this. It should be obvious that an understanding of stuttering implies better understanding of not only how the brain works, but also how it develops in interplay with the environment.

An inductive method for theory construction implies that a synthesis is formed on basis of empirical data. However, it is considered that it still lacks enough data to form such a synthesis. Over the years many authors have nevertheless, of course, presented theoretical propositions of their own. Among them a proposition by Hartman (1994) has to be considered of definite interest, as it is firmly rooted in consistency with existing data.

Hartman thinks like Webster that stuttering does not constitute a speech disorder as such. He rather prefers to look on stuttering as a conditioned behaviour problem than as a handicap. Stutterers normally show fluent speech, but as a consequence of disturbed neuropsychological processes, stutterers are prohibited to speak normally in certain situations. Despite extensive research compelling evidence is missing to support since long cherished notions of stuttering as primarily a consequence of innate or pathological deficiencies. Although the stuttering behaviour disturbs fluent speech it is unrelated both to the development of speech and its performance. Instead he states it is quite evident that stuttering is related to social interaction between a minimum of two people. Hartman thus sees as more realistic that stuttering can be a form of psychosocial behaviour disorder, primarily relating to the individuals traumatic speech related psychosocial experiences. Such a behaviour disturbance reflects a breakdown in the ongoing interaction between the individual and the socio-environment.

Treatment

As with theories, many different treatment programs has seen the light during the years, but I will delimit myself to Hartman's view on treatment since it stands out as having a qualified base in a consistent theory.

Hartman is very critical to current clinical treatment programs that usually hold on to self-administration of mechanistic manipulation techniques, such as controls, starters, avoidances, conditioners, desensitisation, distracters, relaxation measures, etc. He is nevertheless open to supplement his method with distraction- and masking techniques in his clinical work, but confine them to an initial phase. He states that all mechanistic manipulation techniques are ineffective in the long run. The reason is that they all address the symptom stuttering, and what the individual already can, instead of the underlying psychosocial behaviour disturbance. Central for this underlying disturbance is that, in situations where stuttering occurs, the individual systematically drops the confidence in his or her own positive emotional commitment.

The starting-point for a successful treatment must be then to promote a positive emotional commitment and encourage the individual's own interest in social situations. The boosting up of positive emotions with help of encouragement and support is quite a contrast to the usual referring to heavy self-administration. The clinical work should address practical motivation and practical situations that can facilitate and promote the necessary positive emotional commitment in social situations and thereby the access to fluent speech. The focus should be on motif, talents, professional interests, methods and available or potential opportunities to meaningful social activities. The idea is that stutterers who by means of their own positive emotional commitment can be successfully rewarded with immediate speech-gratification, can take advantage of this to motivate continued active social participation, and thereby genuinely strengthen the access to fluent speech. Hartman has practised this treatment method in his own clinical work and the interested reader can take part of a few case studies in his book "The neuropsychology of developmental stuttering" (Hartman,1994).

References

Ahern, G. L. and Schwartz, G. E. (1985). Differential lateralization for positive and negative emotion in the human brain: EEG spectral analysis. Neuropsychologia, 23, 745-755.

Ainsworth, S. (1945). Integrating theories of stuttering. Journal of Speech Disorders, 10, 205-210.

Alm, P. (1995). Stamning. Om stamningens orsaker och behandling, och om hur man själv kan arbeta med sin stamning. Natur och kultur.

Bender, J.F. (1938). The personality structure of stuttering. New York: Pitman Publishing Corp.

Berry, M.F. and Eisenson, J. (1956). Speech Disorders. New York: Appleton-Century-Crofts.

Boberg, E, Yeudall, L, Schopplocher, D. and Bo.Lassen, P. (1983). The effects of an intensive behavioral program on the distribution of EEG alpha power in stutterers during the processing of verbal and visuospatial information. Journal of Fluency Disorders, 8, 245-263.

Carlberg, G. 1989. Dynamisk utvecklingspsykologi. Natur och kultur.

Hartman, B-T. (1994). The neuropsychology of developmental stuttering. London: Wurr Publishers Ltd.

Johnsen, B. H. and Hugdahl, K. 1993. Right hemisphere representation of autonomic conditioning to facial emotional expressions. Psychophysiology. May; 30(3); 274-8.

LeDoux, J. 1998. The emotional brain. The mysterious underpinnings of emotional life. New York: Touchstone.

Misès, R, Ferrari, P. and Roubertoux, P. (1987). Genetique et autisme infantile: Remarques méthodologiques a propos des études sur les jumeaux: La monozygotie facteur de risque? Neuropsychiatrie de l'Enfance; Vol 35, 187-195.

Moore, W.H, Craven, D.C. and Faber, M. (1982). Hemispheric alpha asymmetries of words with positive, negative, and neutral arousal values preceding tasks of recall and recognition: Electrophysiological and behavioral results from stuttering males and nonstuttering males and females. Brain and Language, 17: 211-24.

Moore, W. H. (1984). Hemisperic alpha asymmetries during an electromyographic biofeedback procedure for stuttering: A single-subject experimental design. Journal of Fluency Disorders, 17, 143-162.

Moore, W. H. (1986). Hemispheric alpha asymmetries of stutterers and non-stutterers for the recall and recognition of words and connected reading passages: Some relationships to severity of stuttering. Journal of Fluency Disorders, 11, 71-89.

Morris, J. S, Ohman, A, Dolan, R. J. 1998. Conscious and unconscious emotional learning in the human amygdala. Nature. Jun 4; 393(6684); 467-70

Pauls, D.L. (1990). A review of the evidence for genetic factors in stuttering. Research needs in sturring: Roadblocks and future directions. ASHA Reports No 18, s34-38.

Scarr, S. (1968). Environmental bias in twin studies. Eugenics Quarterly; Vol 15, 34-40.

Van Riper, C. (1971). The nature of stuttering. Prentice-Hall.

Van Riper, C. (1973). The treatment of stuttering. Eaglewood Cliffs, NJ: Prentice-Hall

Van Riper, C. and Emerick, L. (1984). Speech correction: An introduction to speech pathology and audiology. 7th edn. Eaglewood Cliffs, NJ: Prentice-Hall.

Webster, W. G. (1993). Hurried hands and tangled tongues: Implications of current research for the management of stuttering. I Boberg, E (Editor). Neuropsychology of stuttering. Canada: The University of Alberta Press, 73-111.

West, R. (1958). An agnostic's speculation about stuttering. In J. Eisenson (ed.), Stuttering: A Symposium. New York: Harper & Row.

Wood, F, Stump, D, McKeehan, A, Sheldon, S and Proctor, J. (1980). Patterns of regional cerebral blood flow during attempted reading aloud by stutterers both on and off haloperidol medication: Evidence for inadequate left frontal activation during stuttering. Brain and Language, 9: 141-144.

Email to the author: i[dot]b[at]home[dot]se
updated 2001-07-20