Vocabulary Intervention for Late Talkers

Most studies regarding word learning have focused on understanding when and how infants learn words. At 24 months, typically developing infants know between 200 and 300 words and add new words to their vocabularies at a rapid rate. It is also during the first years of life that some principles that promote vocabulary learning are developed. The shape bias, which is a tendency to infer that objects that share the same shape will also share the same name, is the one that has been studied the most. At 24 months, typically developing infants use this principle as a strategy to learn novel words. In contrast, Late Talkers (children with a language delay in the absence of a physiological, cognitive or genetic disorder that may account for this delay) do not exhibit this preference. It has been found that teaching typically developing infants a shape bias prior to the end of the second year of life can boosts their word learning. Despite this, the possibility of teaching Late Talkers this principle and its effect on their vocabulary and language development has not been explored. Over a series of 9 weekly sessions, Late Talkers (diagnosed by Language Therapists from the Birmingham Community Healthcare National Health Services Foundation Trust, United Kingdom) will be introduced to one of two possible interventions: a shape bias intervention and a more conventional intervention called "specific word intervention". Both interventions will be compared after 9 weeks. One year later, a follow up study will be conducted to assess the long-term effects each intervention has in word learning. Participants will be referred by a Speech and Language Therapists from the Birmingham Community Healthcare National Health Services Foundation Trust, United Kingdom, and all assessments and interventions will take place at the Infant and Child Lab at the University of Birmingham, United Kingdom.

The objectives of the present study are: A. To investigate whether it is possible to teach Late Talkers to attend to objects' shapes as a useful property for learning and generalizing novel object labels. B. To assess the benefits that this intervention programme has on Late Talkers' short-term vocabulary development compared to an intervention where infants will be taught specific words ('specific word' intervention). C. Assess whether the success of teaching Late Talkers a shape bias for noun extension is related to their sensitivity to object shape similarities. D. Assess whether the success of teaching Late Talkers a shape bias for noun extension is related to their ability of sustain their attention to novel objects that are presented to them. E. To assess the benefits of the intervention programme on language and cognitive development one year after the intervention compared to the 'specific word' intervention

Over a series of 9 weekly sessions, children diagnosed as Late Talkers will be assessed in different tasks that can be divided into 5 phases: Vocabulary and developmental assessments, initial cognitive assessments, training sessions, word learning test 1, and word learning test 2. Each group (shape training group and specific word training group) will receive a different training programme, however the other assessments will be identical across the groups. In the shape training group, participants will be taught to attend to shape when learning and extending novel labels. In the specific word training group, participants will be taught specific words that they do not know. Before and after the intervention, participants vocabulary will be assessed to compare which intervention enhances word learning. One year later, all participants will be assessed with a language test and a cognitive test. The same assessments will be used in both groups.

Participants will be randomly assigned to one of two posible groups. In both groups, they will receive an intervention, however participants and their parents will not know which one. At the end of the study, participants and their parents will be informed about which group they were in and a document containing a detailed description of each intervention will be provided to them.

This training programme will be similar to a typical word learning intervention. Infants will be introduced to 28 real objects and their names (e.g. biscuit, trousers). These objects will be divided into 7 sets of four words, and during each session, infants will be presented with one of this sets. Each session will consist of a 15 min play session in which each object will be presented at least 10 times and each object name will be mentioned at least 10 times. Additionally, techniques such as focused stimulation and modelling target words, which have proved to be useful for word learning, will be used.

In the shape training intervention, infants will be presented with four novel words paired with four novel sets of objects. Each set consists of two exemplars with the same shape but with different colors and textures, and a contrasting object. Each set will be presented in a play session, and the name of the objects will be mentioned at least 10 times. The other three sets of exemplars will be presented in the same way. Each session will last 15 minutes. This intervention is based on a study conducted by Smith and colleagues (2002), where they found that typically developing infants that are taught to attend to shape at 17 months old, can enhance significantly their word learning.

This intervention is based on on a study conducted by Smith and colleagues (2002), where they found that teaching typically developing infants to attend to shape by the end of the second year of life significantly enhances their word learning. Participants will be taught that the significant property they should focus in when learning and extending novel labels is shape. This will be done through play-like sessions.

In this intervention, participants will be taught the names of 28 real objects. The target words have been selected from the "Wordbank database", which is an open database that lists the proportion of children that know a specific word at a specific age. Twenty-eight words that are understood by 80% of the total child population at 25 months were randomly selected as target words. Techniques such as focused stimulation and modelling target words, which have proved to be useful for word learning, will be used.

Will be assessed by means of a noun extension test with novel names and objects never heard and seen before by the infants at the end of the intervention programme.

In order to assess the benefits of each intervention programme in the infants' general vocabulary development, parents/guardians will fill in a vocabulary checklist filled in before and an intervention (for both types). We will compare the vocabulary growth in the group of children that took part in the shape bias intervention programme with that of the group of children that took part in the 'specific word' intervention. A significant larger increase in the shape bias intervention compared to the 'specific word' intervention will provide information regarding the success or efficacy of the shape bias intervention.

This will be done by assessing infants before (week 1) and after (week 9 ) the intervention programmes.

This will be assessed with a receptive language test. The results will be compared to a standardized mean of the United Kingdom population and will be used to assess if the child caught up in their language development or not.

Each child will be assessed with a standardized test and their results will be used to know if there is an effect of each intervention programme in visual spatial skills.

Each child will be assessed with a standard test and their results will be used to know if there is an effect of each intervention programme in working memory.

Whether children are more receptive to the shape bias intervention if they are sensitive to shape similarities.

Will be assessed by relating children's ability to sort objects by shape before the intervention and their ability to extend object labels by shape after the intervention.

Whether children' are more receptive to the shape bias intervention if they can sustain their attention to novel objects,

Will be assessed by relating children's sustained attention during the presentation of a video showing a person presenting and moving novel objects before the intervention, their attention to the novel objects during the intervention, and their ability to extend object labels by shape after the intervention.

Inclusion Criteria: Children (boys and girls) between 24 and 48 months. Children from Birmingham (United Kingdom) and its surrounding areas. Monolingual English native speakers Children with a moderate or severe language delay, as diagnosed by a Speech and Language Therapist of the Birmingham Community Healthcare National Health Service Foundation Trust, United Kingdom. Exclusion Criteria: Children with a developmental, physiological, neurological or cognitive disorder that could explain their language delay. Children with a mild language delay, as diagnosed by a Speech and Language Therapist of the Birmingham Community Healthcare National Health Service Foundation Trust, United Kingdom. Children that speak or know another language different than English, either as first or additional language.