Lexical-semantic deficits in developmental language disorder: The role of statistical learning

Children with developmental language disorder (DLD) have severe difficulty with the acquisition of language. One hypothesis states that these children have a deficit in the ability of statistical learning, a domain-general learning mechanism that is important for extracting patterns and regularities from input implicitly. This dissertation focuses on the potential link between such a deficit in statistical learning and the lexical-semantic difficulties that are experienced by children with DLD. The following research questions are addressed: 1) do children with DLD have a deficit in various statistical learning abilities (word segmentation; cross-situational word learning and semantic categorization) compared to typically developing children and 2) are these statistical learning abilities related to lexical-semantic knowledge in children with DLD? Another research aim was to investigate ways of measuring statistical learning on-line in children with and without DLD. This dissertation covers four empirical studies. We found evidence for a deficit in cross-situational word learning in children with DLD, indicating that they have more difficulty than typically developing children with learning to couple words to their referents in situations with referential ambiguity. We did not find evidence for or against a deficit in the other types of statistical learning ability in children with DLD, nor did we find evidence for or against a relationship between statistical learning and lexical-semantic knowledge. Concerning our on-line measures of statistical learning, using eye-gaze data as an index of cross-situational word learning shows promise

DATA ANALYSIS - Implicit cross-situational word learning in children with and without developmental language disorder and its relation to lexical-semantic knowledge

This collection includes the data files, R scripts, html fies and graphs that belong to the collection 'Implicit cross-situational word learning in children with and without developmental language disorder and its relation to lexical-semantic knowledge'.  -CSL_Test is the accuracy data from the test phase -CSL_ET_clean is the eye-tracking data from the familiarization phase -CSL_regression_DLD is the data that i used in the regression analysis on the relationship between cross-situational word learning and lexical-semantic knowledge in children with DLD. These data files are used in the RMD files for data analysis. One RMD file and one html file is provided for each of the three different analyses (test phase, eye-tracking, regression).</p

Cross-situational word learning in children with and without DLD and its relation to lexical-semantic knowledge

   Research indicates that statistical learning plays a role in word learning by enabling the learner to track the co-occurrences between words and their visual referents, a process that is named cross-situational word learning. Word learning is difficult for children with developmental language disorder (DLD). A deficit in statistical learning has been suggested to contribute to the language difficulties in these children. In the current study we investigate whether children with DLD have more difficulty than TD children with learning novel word–referent pairs based on cross-situational statistics in an implicit task, and whether this ability is related to their lexical-semantic skills. Moreover, we look at the role of variability of the learning environment. In our implicit cross-situational word learning task, each trial in the exposure phase was in itself ambiguous: two pictures of unknown objects were shown at the same time and two novel words were played consecutively, without indicating which word referred to which object. However, as every word occurred with its correct referent consistently, the children could learn the word–referent pairs across trials. The children were not explicitly instructed to learn the names of new objects. As an on-line measure of learning, eye-movements were recorded during the exposure phase. After exposure, word–referent knowledge was also tested using multiple choice questions. Different measures of lexical-semantic knowledge were administered to the children with DLD, as well as tasks measuring non-verbal intelligence and phonological processing. Contextual variability (the number of different distractors with which a particular word–referent pair occurs across trials) was manipulated between subjects by constructing two types of exposure conditions: low contextual diversity vs. high contextual diversity. Both groups of children performed significantly above chance level on the test phase, but the TD children significantly outperformed the children with DLD. This indicates that children with DLD have more difficulty with implicit cross-situational word learning. We found no significant effect of contextual diversity. The eye-tracking data revealed some evidence of online learning, but no differences between groups. The regression analyses did not reveal any significant predictors of off-line or on-line cross-situational word learning ability.</p

Cross-situational word learning in children with and without DLD and its relation to lexical-semantic knowledge

   Research indicates that statistical learning plays a role in word learning by enabling the learner to track the co-occurrences between words and their visual referents, a process that is named cross-situational word learning. Word learning is difficult for children with developmental language disorder (DLD). A deficit in statistical learning has been suggested to contribute to the language difficulties in these children. In the current study we investigate whether children with DLD have more difficulty than TD children with learning novel word–referent pairs based on cross-situational statistics in an implicit task, and whether this ability is related to their lexical-semantic skills. Moreover, we look at the role of variability of the learning environment. In our implicit cross-situational word learning task, each trial in the exposure phase was in itself ambiguous: two pictures of unknown objects were shown at the same time and two novel words were played consecutively, without indicating which word referred to which object. However, as every word occurred with its correct referent consistently, the children could learn the word–referent pairs across trials. The children were not explicitly instructed to learn the names of new objects. As an on-line measure of learning, eye-movements were recorded during the exposure phase. After exposure, word–referent knowledge was also tested using multiple choice questions. Different measures of lexical-semantic knowledge were administered to the children with DLD, as well as tasks measuring non-verbal intelligence and phonological processing. Contextual variability (the number of different distractors with which a particular word–referent pair occurs across trials) was manipulated between subjects by constructing two types of exposure conditions: low contextual diversity vs. high contextual diversity. Both groups of children performed significantly above chance level on the test phase, but the TD children significantly outperformed the children with DLD. This indicates that children with DLD have more difficulty with implicit cross-situational word learning. We found no significant effect of contextual diversity. The eye-tracking data revealed some evidence of online learning, but no differences between groups. The regression analyses did not reveal any significant predictors of off-line or on-line cross-situational word learning ability.</p

DATA ANALYSIS - Implicit cross-situational word learning in children with and without developmental language disorder and its relation to lexical-semantic knowledge

This collection includes the data files, R scripts, html fies and graphs that belong to the collection 'Implicit cross-situational word learning in children with and without developmental language disorder and its relation to lexical-semantic knowledge'.  -CSL_Test is the accuracy data from the test phase -CSL_ET_clean is the eye-tracking data from the familiarization phase -CSL_regression_DLD is the data that i used in the regression analysis on the relationship between cross-situational word learning and lexical-semantic knowledge in children with DLD. These data files are used in the RMD files for data analysis. One RMD file and one html file is provided for each of the three different analyses (test phase, eye-tracking, regression).</p