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Project

The interaction between stuttering and gestures, and its influence on the intelligibility of individuals with Down syndrome

Stuttering, a multicomponent fluency disorder wherein speech is disrupted by involuntary part-word repetitions, prolongations and blocks, frequently occurs in individuals with Down syndrome. Down syndrome (DS), the result of an extra copy of chromosome 21, is characterized by specific weaknesses and strengths in the functioning of individuals with this diagnosis. Weaknesses in their language and speech abilities often result in diminished speech intelligibility and stuttering can exacerbate this. Unfortunately, weaknesses in their cognitive abilities, such as the severity of their intellectual disability and deficits in their working memory, often impede the use of traditional stuttering therapies in these individuals. However, a strength in gesture use appears to aid their language production. Until now, it remains unexplored if gestures can also aid speech production in case of stuttering.

 

            The main purpose of this project was to determine if gestures are suitable to reduce stuttering and improve speech intelligibility and comprehensibility in individuals with DS. One advantage of gestures would be that they could affect the stuttering events without making the individual with DS aware of the stuttering. Awareness might be absent and inducing awareness by directly addressing stuttering in therapy could have an adverse affect on their emotional wellbeing and increase stuttering severity. Gesture use might evade this effect. Another advantage is that gestures are part of daily communication. Learning new behaviours is particularly difficult for individuals with DS and gestures aid the therapists to build upon behaviours they already possess to improve their speech production.

 

            This main goal resulted in four research objectives, addressed in four different studies. The first objective was to investigate the awareness of stuttering in individuals with DS and to compare it to typically developing (TD) individuals. Awareness was tested with a novel instrument adapted to the abilities of this population. The second objective was to discover the natural interaction between gestures and stuttering in individuals with DS and TD individuals. This interaction was observed in spontaneous speech samples of these participants. The third objective was to learn the effect of gestures on the intelligibility and comprehensibility of utterances with stuttering events of individuals with DS. Naïve adult TD listeners judged the intelligibility/comprehensibility. The fourth and final objective was to examine the effect of deliberate gesture use on the stuttering frequency of individuals with DS via an experimental set up.

 

            The first study indicated that developmental age might play an important role in the growth of awareness of stuttering in both individuals with DS and TD individuals. However, the study showed that the novel instrument needs significant adaptations before it could be used clinically. The other three studies could not conclude that gestures could be used in stuttering therapy but there were some promising results in that direction. The second study showed that individuals with DS spontaneously use more gestures during stuttering events than during fluent speech, which might indicate a subconscious motivation to compensate for the interruption of speech. Notably, these results were different from those of the TD individuals, who showed no difference in gesture use during stuttered or fluent speech. Unfortunately, in the DS group, only approximately 30% of the stuttering events was accompanied by a gesture and while it was shown that a gesture could occur during a stuttering event, the exact interaction with the stuttering event remains unclear. The third study, however, did show that these gestures improved the intelligibility and comprehensibility of the utterances with stuttering events. The last study showed that at group level the deliberate use of gestures indirectly reduced stuttering frequency through reduction of the articulation rate. However, individual analyses showed that gesture use did not lead to a reduced articulation rate in all participants and that a reduced articulation rate did not cause a positive effect on everybody’s fluency. It appeared that different characteristics of the individuals influenced the ability of gestures to reduce stuttering.

 

            These results provide a starting point for several future research directions. One direction could work on refining the awareness test to make it available for clinical use. Additionally, the attitude of individuals with DS towards stuttering should be investigated because both awareness and attitude are important aspects to consider during the choice of therapy. Another direction is further research into the possible implementation of gestures in stuttering therapies. Future research needs to discover what triggers the occurrence of gestures during stuttering events and elucidate the exact temporal interaction between gestures and stuttering events. Furthermore, it is important to examine which characteristics bolster the positive effect of gesture use on fluency in individuals with DS. The first research direction will further aid speech-language pathologists in deciding on the best therapy approach and the second research direction will possibly lead to the development of stuttering therapies wielding the gesture strength of individuals with DS.

Date:1 Sep 2018 →  11 Oct 2022
Keywords:Stuttering, Down Syndrome, Gestures
Disciplines:Neurosciences, Biological and physiological psychology, Cognitive science and intelligent systems, Developmental psychology and ageing
Project type:PhD project