The Effect of Spontaneous Hand Gestures on Stuttering in Children With Down Syndrome

This study wants to determine the influence of spontaneous hand gestures and gestural priming on stuttering in children with Down syndrome.

Children with Down syndrome have inherently a low IQ (20-60), language deficiencies that cannot be explained completely by the mental disability and pronounced facial features. One third of these children also has fluency problems. Fluency problems in children with Down syndrome are normally stuttering and/or cluttering. This study focuses primarily on stuttering.

There are many therapies for stuttering, but there are very few for children with Down syndrome. Many of these therapies request specific skills like self-reflection and self-judgment which are very difficult or impossible for people with intellectual disabilities. There is need for a new therapy that considers the strengths of children with Down syndrome. Therefore, this study will first observe what the impact of these strengths are on the stutter frequency and severity of children with Down syndrome.

Strengths of these children are: a strong visual short-term memory, a big receptive vocabulary, imitation, sense of rhythm, interests in other people and the ability to use spontaneous gestures to compensate for their language problems. Consequently, this study will see with the effect is of spontaneous gestures on their stuttering.

These gestures should not be confused with signs from a sign language or sign system. Signs are taught, while gestures appear spontaneously. In Belgium they often teach children with Down syndrome ' Speaking with Support of Signs'. This is a sign system where the children learn to support the key words of their sentence with a sign so that they are better intelligible.

This study is observational and has three research questions. The first question is: Do children with Down syndrome who stutter use more spontaneous hand gestures than children with Down syndrome who do not stutter? The hypothesis is that the children who stutter will indeed make more gestures because they have to compensate for not only language problems but also fluency problems. The kind of spontaneous hand gestures will also be considered and if herein is a difference between the groups.

Within this research question, the impact of the use of gestures on the stutter frequency will be investigated. The researchers believe that the more gestures they use, the lower their stutter frequency will be, because they follow the hypotheses that speech and gestures are controlled by the same brain areas. If the children know SMOG, they will also control for the effect of SMOG on the stutter frequency.

The second research question is: 'Does gestural priming have an influence on the fluency of children with Down syndrome? Gestural priming is a secondary speech signal that gives feedback to the first speech signal by simultaneously mimicking the first speech signal. In this research a hand puppet will imitate the mouth movements of the participants in several conditions based on earlier research from Snyder, Waddell and Blachet. The hypothesis is that due to the function of mirror neurons, the participants will become more fluent. Mirror neurons are neurons in the brain that help progress speech by activating the motoric regions of speech when an individual sees someone speak and they can produce a neural basis for fluency by the perception of the second speech signal.

The last research question is: Can gestural priming help someone through a stuttering moment? The researchers believe that gestures and speech are controlled by the same brain regions. Therefore, if someone makes movements while some else is in a stuttering moment, this might help the participant to break through the stuttering moment.

Before the start of the study, language tests are done to see if the participants have a high enough language level to participate. They also get a stutter test to get an idea about their attitude towards their stuttering.

The study itself is divided into three research questions. For the first research question, the frequency and kind of gestures are investigated. Next to that, the impact of these gestures on the stuttering frequency is measured. To collect this information, a spontaneous telling task and a retell task will be videotaped to be analysed.

All the participants get a spontaneous telling task, namely the RTOS. In this test they tell what they see on a picture. The investigator first gives an example without explicit hand gestures and then the children must tell stories with three pictures. The investigator can encourage the children to make real stories and to not just numerate all the items on the picture. This can be a challenge because of their intellectual disabilities. If there is not enough spontaneous speech collected during the RTOS, the researcher will start a conversation with the child about a topic of the child's interests.

In the retell task, the investigator tells a story and makes 'spontaneous gestures' while doing this. After that the participants need to repeat the story as well as they can. The length of the sentences will be adjusted to the language level of the participants. The story used is 'Pie for Bear' [Taart voor beer], a story that was adapted to people with intellectual disabilities by adding manual signs. For this study, the manual signs will be exchanged for spontaneous hand gestures. These spontaneous gestures will be decided in advance, so that it is the same for all the participants.

For the second research question, only the group of children who stutter is retained and divided into three groups. Each group does the same procedure four times, with each time a different condition, based on the procedure of Snyder, Waddell & Blachet. There are three experimental conditions and one control condition. In the control condition, the investigator gives a sentence and the participant must repeat it immediately after. The sentences will be at least three words long, depending on the language level of the contestant, and each session has 20 sentences. In the control condition no gestures or priming is used. The experimental conditions are the same, but priming is induced. In the first experimental condition, the participant gets a hand puppet that must make the same mouth movements as she does, but the puppet needs to start moving before the participant starts talking. In the second experimental condition, the participant does the same thing with the hand puppet, but she has to hold it behind a screen, so she cannot see it herself.

In the third condition, it is the investigator who simultaneously mimics the participant with the hand puppet. The groups do all the conditions, but in a different order, so there is control for a saturation effect.

For the last research question, the third condition will be retaken, but this time the investigator only moves the mouth of the puppet when the participant is in a stuttering moment.