Abstract
Children with developmental language disorder (DLD) frequently have difficulties with word learning and understanding vocabulary. This can significantly impact social interactions, daily activities, and academic progress. Although there is literature providing a rationale for targeting word learning in such children, there is little evidence for the effectiveness of specific interventions in this area for children with identified DLD and particularly for older children. The purpose of this study was to establish whether direct one-to-one intervention for children with DLD over 9 years of age leads to improved abilities to identify, comprehend, define, and use nouns and verbs targeted in intervention compared with non-targeted control items and whether the participants’ rating of their own knowledge of the words changes with intervention.
Procedures
Participants were 25 students with language disorder ages 9 to 16 years (the majority with DLD; some with autism spectrum disorder [ASD]). Words were taken from Bauman and Culligan’s (1995) General Service List (GSL) of a total of 2,000 words deemed most used by people speaking and learning English. Two lists of words were used: higher level (less frequent) and lower level (more frequent). Words were selected by judgment on their functionality, but words directly related to curriculum subjects were omitted. Each participant’s speech-language pathologist (SLP) judged which level would be most appropriate for them based on standardized assessment results and observation. The hypothesis was that children with limited vocabulary would benefit from learning and consolidating more frequently used vocabulary due to the functionality of the words, whereas those who were able to use and understand the lower level words in context would benefit from focusing on higher level vocabulary rather than relearning words they already know. Each list had 20 nouns and 20 verbs. There was a preassessment and then 30-min sessions for 7 weeks.
Assessments
Four assessment tasks of varying levels of difficulty were used to obtain an understanding of each participant’s word knowledge and to measure change in participants’ word knowledge:
Task 1: Lexical decision. The evaluator read a list of 40 words and 40 non-words aloud. Participants were asked to say whether each was a real word or not. The 40 non-words were derived from the real words by changing a vowel or consonant in each syllable of the word.
Task 2: Multiple choice. Participants were presented with a word and a choice of three possible definitions (verbally and in writing). They were allowed repetitions of each question and were asked to say “a,” “b,” or “c” or point to one of these as their response.
Task 3: Definition production. The evaluator was provided with a recording sheet that consisted of three columns: the target word, the child-friendly definition, and a blank column to record students’ responses. Students were asked to give the meaning of each word. Words were presented verbally and in written form. The following scoring system was used: 1 point—all key concepts of word definition; 0.5 points—partial knowledge of word; 0 points—incorrect or no response.
Task 4: Sentence production. Students were asked to use each word within a sentence. Words were presented verbally and in written form. Responses were scored in the following way: 1 point—semantically and syntactically correct sentence; 0.5 points—partially correct or semantically correct but syntactically incorrect; 0 points—completely incorrect or no response.
Self-evaluation of word knowledge. Prior to giving a definition, participants rated their knowledge of each word using a symbolized traffic light system that required participants to rate their own knowledge of each word as red, amber, or green. These were converted to a score of 1, 2, or 3 for each word. These scores were used to assess the participant’s perception of their word knowledge and to monitor change in this for treated and control words after intervention.
Intervention Methods
Sessions 1–5
Two target words were introduced in each of the sessions. The SLP presented the word in isolation in spoken and written forms. The student predicted whether the word was a noun (naming word) or a verb (doing word) and used any prior knowledge of it to predict its meaning. The SLP gave its definition in verbal and written forms, discussed these with the student, and reviewed their prediction of word class and definition. The student then recorded the word meaning on the new word poster. The phonological features of the word were reinforced by:
The student and SLP repeating the word together;
Identifying each phoneme in the word;
Clapping out the word and counting the syllables;
The student completing the “what does it sound like?” section of the poster (i.e., number of syllables, first sound, last sound, and rhyming words).
The meaning of the word and examples of when it may be used were discussed. The student recorded the definition on the word poster. The student then made two cue cards: on one they wrote the target word and on the other they drew a picture to help them remember the word and its meaning. This process was repeated with the second target word.
During the final 10 min of the session, a game activity was used to reinforce the phonological, orthographic, semantic, and syntactic features of each word. The cue cards with the written words were displayed and labeled as Word 1 and Word 2. The picture cards were placed face down on the table. A set of instruction cards were introduced and the student selected a card and followed the instruction, for example:
Definition cards (with two definitions for each word to avoid rote learning of definitions): The student matched the definitions to the appropriate word.
Definition production: The student was asked to produce a definition for one of the words.
Sentence starters: The card showed the beginning of a sentence containing one of the target words, and the student participant was asked to complete the sentence.
Sentence production: The student was asked to generate their own sentence containing one of the words.
Spelling: The student was asked to spell one of the words.
At the end of the session, the SLP asked the participant to recall the two new words and their meanings and summarized what they had achieved. A 5-min revision session was carried out with each student between intervention sessions. This consisted of a game of matching pairs using the student’s cue cards of all the words they had learned to date. All of the cue cards were placed face down on a table; the student and SLP took turns in selecting a card and would then try to find the picture or word card that matched to make a pair. For each card selected, the student was asked to recall the word and its meaning.
Sessions 6 and 7
The two final sessions were used to review the 10 target words. The matching pairs game was carried out with all 10 words (20 cue cards—one written card and one picture card for each word). This was followed by a game where a participant’s picture cards were placed face down on the table. The student selected a card and carried out an instruction or question. This process was repeated until they had completed the activity for all target words. The instructions/questions used for this activity were the following:
Try to spell the word.
Can you make a sentence using your word?
Can you explain the meaning of your word?
Is the word a noun or a verb?
How many syllables are in the word?
What sounds are in the word?
If your word is a noun, what does it look like?
If your word is a verb, when might someone do this?
Results
Students in the intervention group improved on all assessment tasks. Scores of students on the intervention words improved by 19% compared with 8% for control words.
The assessment tasks differed in difficulty. Student performance was best on lexical decision, followed by multiple choice and then sentence production and definition.
The percentage accuracy of students assigned to the higher level of difficulty was significantly greater than for those at the lower level.
There was no difference between students diagnosed as DLD or language disorder associated with ASD.
Overall, students’ improvement for nouns and verbs was similar. However, the improvement in nouns was mainly due to those directly targeted, whereas improvement in verbs was more evenly divided between treatment and control items.
Treatment of verbs appears to lead to greater generalization than treatment of nouns.
On lexical decision, the easiest task, accuracy for verbs improved more than for nouns (nouns were already at high accuracy).
On the more difficult tasks (sentence production and definition), improvement for nouns was greater than for verbs
Discussion
This study showed one-to-one vocabulary intervention with an SLP to be effective for teaching targeted vocabulary to participants between 9 and 16 years of age with identified DLD. The intervention was intensive, targeting only 10 words, but relatively undemanding of therapy resources (a mean of 3 hr 14 min). Student learned approximately four new words. This progress is greater than progress in some other studies with a greater amount of intervention time: one to two words after 10-hr intervention (Spencer et al., 2017) or two words after 18 hrs (Lubliner & Smetana, 2005). These results were similar to the progress of four words found by Snow et al. (2009) after almost 10 times the amount of intervention. The authors suggest that the greater progress found in their study may be due to the one-to-one delivery of intervention. The intervention method in this study focused mainly on the semantic and phonological aspects of the words, along with some work on identifying parts of speech and using targeted words in sentences, and included multiple exposures, repetitions, and rehearsals. This approach is in accordance with the strategies predicted to help children with DLD who have difficulties with word learning and similar to the Parsons et al. (2005) and St. John and Vance (2014) studies. The study does not address which aspects of the intervention may be most important.