The roles of maternal input in facilitating child language development have ... during the early stages (Tager-Flusberg et al., 1990; Swensen et al (in press);.
Does Maternal Input Affect the Language of Children with Autism? Lauren D. Swensen, Letitia R. Naigles, and Deborah Fein University of Connecticut
1. Introduction Much research has explored how the lexical, grammatical, and pragmatic aspects of child directed speech subsequently affects children’s language acquisition (Hoff, 2003). Virtually all children are exposed to natural language in some shape or form; however, mothers vary in how talkative they are, how much they ask their children questions vs. making declarative statements, their usage of nouns versus verbs, their sentence length, etc. It is this variability in linguistic input that has allowed researchers to examine which aspects of linguistic input are most influential on their children’s language (Hoff-Ginsberg, 1985). In contrast, little research has investigated how the various aspects of maternal input affect the language development of children with autism. Language impairment is a clinical feature of the diagnosis of autism in children (APA, 2000). The language of children with autism is characterized by an overall language delay (Tager-Flusberg, 2001). Children with autism show relative strengths in lexical and grammatical components of language indexed in vocabulary growth and early comprehension of English word order (Swensen et al., in press). Their most severe deficits are seen in the social-pragmatic domain of language, involving conversational and storytelling skills (Tager-Flusberg & Anderson, 1991; Loveland et al., 1990). Children with autism who undergo language therapy seem to make the most progress and of course, for these children, much of their input comes from their therapists, some of whom use a rigid schedule of language presentation, such as Applied Behavior Analysis (ABA) (Lovaas, 1987). Clinical observation has suggested though that the children who show the most language gains are those who begin to learn language incidentally, i.e. from listening to regular/normal/social discourse The current study explores the input-outcome relationships in children with autism and their mothers, asking whether children with autism demonstrate similar sensitivities to maternal input as have been shown in typically developing children. The roles of maternal input in facilitating child language development have been explored in many domains of language. Grammatical elements of maternal speech have been found to correlate with several aspects of child language. For example, Newport, Gleitman, and Gleitman (1977) found that mothers’ frequency of asking yes/no questions (1) and expanding on children’s prior utterances (2) was positively related to children’s subsequent growth in auxiliary
use. (1) (2)
Question: Do you want to play with the doll? Expansion:*CHI: Paint shirt *MOT: You were painting her shirt.
Relationships have also been found between pragmatic aspects of maternal speech and child language. For example, Hoff-Ginsberg (1985) found that maternal use of expansions and self-repetitions was positively correlated with the child’s subsequent number of verb phrases per utterance (a measure of grammatical complexity). Thus, both maternal questions and expansions facilitate children’s grammatical development. For a more exhaustive review of the role of input in typical children’s language development see Hoff (2003). In contrast, research on the role of maternal input for the language development of children with autism has been quite limited in scope. Most of the available research has simply compared maternal speech to children with autism with maternal speech to typically developing children, finding that mothers of children with autism seem to speak to their children similarly to mothers of typically developing children, finding few differences between the two. That is, they do not appear to differ on MLU (Mean Length of Utterance; the number of grammatical morphemes per utterance) and proportions of directives, suggestions, comments, questions, and labels when compared at similar child language levels; however, mothers with ASD tend to produce more utterances (Wolchik, 1983). Mothers of children with autism also appear to adjust their speech to the linguistic abilities of their children, in that mothers of children with higher verbal abilities use more questions, reinforce more language behavior, and model language more, while mothers with children who have less linguistic ability use more directives and reinforce motor behavior more (Konstantareas et al., 1988). Additionally, mothers of children with higher receptive skills seem to use more child-focused utterances and fewer out–offocus utterances; however, mothers of children with autism used more out-offocus utterances when compared to mothers of typically developing children (Watson, 1998). In sum, mothers of children with autism do not appear to talk very differently from mothers of typically developing children; however, this research does not reveal whether these children are making use of the input that they are receiving. Only one study has investigated this, demonstrating that mothers who engage in more joint attention, have children who progress in syntax (measured by the Index of Productive Syntax) more quickly (Rosenthal Rollins & Snow, 1998). Thus, while research with children with autism has made contact with the questions concerning the role of input in language acquisition, this literature still has many gaps. The current study begins to fill these gaps, investigating two specific relationships: (1) Do children with autism show the documented
relationship between maternal use of Y/N-questions and child use of auxiliaries found in typically developing children (Newport et al, 1977)? (2) Do children with autism exhibit the relationship between maternal expansions and improvements in child language that have been found in typically developing children (Hoff-Ginsberg, 1985)? We predict that because the acquisition of grammar in children with autism seems to proceed fairly typically, especially during the early stages (Tager-Flusberg et al., 1990; Swensen et al (in press); Kelley et al., 2006), children with autism should be able to use maternal questions. However, they may not pay attention to expansions due to the fact that these may be connected to the pragmatic domain of language. 2. Methods 2.1. Participants 2.1.1. Autism Spectrum Disorder (ASD) This group consisted of 10 boys with Autism Spectrum Disorder (ASD). They were recruited through treatment facilities and schools in Connecticut and New Jersey. The children ranged in age from 27 to 41 months at the onset of the study (mean=33.4 months, SD=4.06); the study lasted just over a year and included four visits, each four months apart. All of the children were diagnosed with ASD or Pervasive Developmental Disorder (PDD) by clinicians prior to the beginning of the study. Due to the difficulty in distinguishing between the two disorders before age three, either diagnosis was accepted. We confirmed this diagnosis with the ADOS (Autism Diagnostic Observation (ADOS; Lord, Rutter, Goode, Heemsbergen, Jordan, Mawhood, & Schopler, 1989) prior to start of the study. All of the children were at the very early stages of language development. All the children were within 8 months of the start of an ABA program (either inside or outside of the home) and were receiving 5 to 30 hours of ABA therapy a week (mean=16.4, SD=9.1) at the onset of the study. 2.1.2. Typically Developing Children (TYP) This group consisted of four boys and six girls. None of the children had been diagnosed with ASD or PDD, which was confirmed with the ADOS at the initial visit. The TYP group was recruited from a database of children at the UConn Child Language Lab. The intention was that the children would match the ASD group in language production level at the onset of the study, and at relevant comparisons throughout. Therefore, they were first recruited at the ages of 15-17 months (Mean=16.6 months, SD=0.61) and followed for just over a year, including four visits each four months apart. The two groups had similar vocabularies and overall levels of grammar, as shown by their word types and MLU in spontaneous speech, and their CDI (Fenson, Dale, Reznick, Thal, Bates, Hartung, Pethick, & Reilly, 1991) vocabulary production scores at visits 2 and 3 (see Figures 1-3.).
80
70
60
50 ASD
40
TYP
30
20
10
0 Visit1
Visit2
Visit3
Visit4
Figure 1. Word Types by Visit and Group, from Spontaneous Speech
3
2.5
2
ASD TYP
1.5
1
0.5
0 Visit1
Visit2
Visit3
Visit4
Figure 2. MLU by Visit and Group, from Spontaneous Speech 500 450 400 350 300 ASD TYP
250 200 150 100 50 0 Visit1
Visit2
Visit3
Figure 3. CDI Production Scores by Visit and Group 2.2. Measures
Visit4
Data from visits 1-4 were collected within the context of an ongoing longitudinal study of language development in children with autism. Data were collected at the children’s homes. At Visits 1-4 (ASD: 33-45 months old; TYP: 17-29 months old) the children were administered in a variety of standardized language measures, and participated in a 15-minute free play session with their mothers. The standardized tests measured level of autism, communication skills, and vocabulary. Autism Diagnostic Observation Schedule. (ADOS; Lord et al., 1989) The ADOS is a structured play session that yields scores in Communication, Social Interaction, Play and Atypical Behaviors, which permit diagnosis of autism by DSM-IV criteria. MacArthur Communicative Development Inventory (CDI). (Fenson et al., 1991) The infant and toddler versions are parent reports which assess children’s language in a variety of areas. The infant version assesses the number of vocabulary items understood (comprehension), and understood and said (production) for children 10 to 18 months in age. It consists of 396 words, of which 360 are open class content words (Noun, Verb, Adjective) and 36 are closed class words (e.g. pronouns, question words) (Gleitman & Wanner, 1982). It also includes a list of 28 phrases the child might comprehend. It has been normed for children from 8- to 16-months in age. The toddler version assesses vocabulary size and grammatical complexity in production only, and had been normed for children 16-30 months of age. It consists of 608 words including a wide variety of nouns (n=371+) and verbs (n=103+), plus a section of utterances, one of which is more linguistically sophisticated than the other (e.g. he go vs. he is going). The infant version was administered at visits 1 and 2 and the toddler version was administered at visits 3 and 4. 2.3. Transcription and Coding The 15-minute free play interactions were transcribed and later coded for specific elements relevant to the research questions. Research question one explored the relationship between maternal Y/N questions and child auxiliaries. Each transcript was reviewed and a frequency count of each of these two elements was tabulated (See Table 1.).
Table 1. Mean Maternal Questions and Child Auxiliary Production # Child Aux # Maternal Y/N Qs (SD) (SD) Visit 1
Visit 2
Visit 3
Visit 4
Maternal MLU (SD)
ASD
-
24.4 (24.3)
4.1 (0.5)
TYP
-
37.6 (23.1)
4.6 (0.7)
ASD
-
34.0 (14.3)
4.2 (0.8)
TYP
-
35.6 (20.1)
4.4 (0.7)
ASD
-
32.9 (27.5)
4.8 (0.5)
TYP
1.8 (2.4)
39.8 (14.5)
5.0 (0.7)
ASD
4.1 ( 4.5)
NA
NA
TYP
3.3 (3.3)
NA
NA
Research question two explored the relationship between maternal expansions and several indices of child language development. An utterance was considered an expansion if it stayed on the same topic of the child’s previous utterance but added additional elements (e.g. (2) above). Each transcript was reviewed and a frequency count of maternal expansions and these child production elements, which included # of uses of “I want…”, # of determiners, # of tokens, # of types, # of plurals, and # of past tense (see Table 2). The number of verb phrases wasn’t calculated (as done in Hoff-Ginsberg, 1985) due to the fact that there was little variation on this measurement, as almost all child utterances had just one verb phrase per utterance.
Table 2. Maternal Expansions and Child Production Group Means (SD) Input
Child
Child Child
Child
Child
# Expansions # I want # Det # Tokens # Past # Plurals Tense Visit 2 ASD
6.2 (3.5)
TYP
5.8 (10.0)
Visit 3 ASD
8.2 (6.9)
1.4 (1.8) 15.7 162.8 (27.7) (147.1)
1.3 (1.3)
1.5 (1.7)
TYP
9.8 (7.6)
0.6 (1.3) 6.2 136.8 (8.3) (110.0)
1.2 (1.4)
4.6 (8.0)
Visit 4 ASD
2.7 (5.2) 8.2 176.6 (9.8) (112.2)
1.9 (2.5)
2.1 (2.6)
TYP
1.7 (2.5) 9.9 271.4 (9.3) (122.3)
2.2 (2.3)
3.5 (3.7)
3. Results 3.1. Descriptives Language production measures were analyzed at each visit to make comparisons between language ability for the ASD and TYP groups. T-tests revealed no significant differences between the two groups at visits 2 and 3 on the number of word types and MLU in spontaneous speech, nor on their CDI scores (ps ranged from 0.16-.99), see Figures 1-3. 3.2. Analysis 1 Analysis 1 explored the relationship between the maternal use of Y/N questions and child auxiliary use. Y/N questions can influence many aspects of child grammar. With that in mind, child MLU at visit 2 and visit 3 were partialed out of the following correlations because it is important to demonstrate a specific, rather than a general, effect of maternal speech and child grammar. That is, is it possible that maternal Y/N questions only assist children with higher MLUs or better grammar to start with. The children with higher MLUs at visit 2 might show more auxiliaries at subsequent visits, regardless of their input just because they are more advanced to begin with. So, by partialling out initial MLU we are equalizing the children on their level of initial language (See Hoff, 2003 for an example).
For the TYP group, a significant correlation was found between maternal Y/N questions at visit 2 and child auxiliary use at visit 3, with child MLU at visit 2 partialed out (r =.73, p =.026). For the ASD group, no significant correlation was found between maternal Y/N questions at visit 2 and child auxiliary use at visit 3. However, for the ASD group, a significant correlation was found between maternal Y/N questions at visit 3 and child auxiliary use at visit 4, with child MLU at visit 3 partialed out (r =.86, p =.003). Thus, the partial correlations show a positive relationship between the number of maternal Y/N-Questions and the child’s subsequent use of auxiliaries in spontaneous speech. The TYP children provide evidence of making use of their mothers Y/N questions at Visit 2, while the ASD group appears to make use of maternal Y/N questions at Visit 3. 3.3. Analysis 2 Analysis 2 explored the relationships between maternal use of expansions and child language. The maternal expansion measure came from visits 2 and 3. Child production measures were drawn from visits 3 and 4. These consisted of several child language variables from the spontaneous speech sample (see Table 2.) and the standardized language production score from the CDI. Partial correlations were conducted. As with the previous analysis, child MLU at visit 2 and visit 3 were partialed out to ensure that the effect of maternal speech was not just occurring for those children with higher initial grammatical levels. For the TYP group, several significant correlations were discovered. Maternal expansions at visit 2 were correlated positively with the child use of “I want” (r =.80, p =.010), determiners (r =.67, p =.048), past tense (r =.74, p =.024), the number of tokens in child speech (r =.73, p =.02), and the CDI production scores (r =.69, p =.040) at visit 3. For the ASD group, no significant correlations were found between maternal expansions at visit 2 and any of these child language measures at visit 3. However, significant correlations were found between maternal expansions at visit 3 and child use of plurals (r =.74, p =.036) and their CDI production scores (r =.73, p =.040) at visit 4. Thus, these partial correlations show a positive relationship between the number of maternal expansions and the child’s subsequent language use. The TYP children provide evidence of making use of this input at visit 2, while the ASD group appears to make use of expansions at visit 3. 4. Discussion In analysis one, we discovered a positive relationship between maternal Y/N questions and both typical and ASD children’s use of auxiliary verbs. Why do Y/N-questions help children learn auxiliaries? As discussed by Newport and colleagues, (Newport, Gleitman, & Gleitman, 1977), these types of questions place the auxiliary in the utterance-initial position in the sentence (e.g. see (1)), which has been suggested to be one of the two most salient positions in the
sentence (utterance-final is the other) when children are learning language (Slobin, 1972; Fernald, 2002; Shatz, Hoff-Ginsberg, & McIver, 1989). So, Y/N-questions provide children with the auxiliary in a position that is in line with their processing strategies. The partial correlations show a relationship between the number of maternal Y/N-Questions and the child’s subsequent use of auxiliaries in spontaneous speech. But, the TYP children are making use of their moms’ Y/N questions at Visit 2, while the ASD group isn’t making use of this until Visit 3. Despite having equivalent language at visit 2 this relationship occurs at different developmental times for each group. In analysis two, we explored the relationship between maternal expansions and subsequent child language. Why might maternal expansions important in advancing the language of their children? Expansions stay on the same meaning of the child’s utterance, but add more grammatical elements (e.g. see (2); HoffGinsberg, 1985). In theory, this provides the child with a model for the grammar they should be using, were they producing longer utterances. For both our TYP and ASD children the predictive relationships between maternal expansions and subsequent child language skills emerges, but again this relationship is occurring later for the children with autism. This differs from previous research that found no differences in this relationship for low-education mothers where the mothers may have been behaving differently yet no differences in the children’s language was seen (Hoff-Ginsberg, 1994). This differs from the current study where the mothers were behaving similarly, yet differences in the timing of the input relationships were seen. When we combine the results of our two analyses we can make a general conclusion: similar relationships were found between the two groups. This conclusion is important for two reasons. First, these finding replicate input relationships found in previous research with typically developing children. Second, these input relationships were found for our children with autism as well. This suggests that there is some similarity in the linguistic influence of maternal speech on both typically developing and children with autism. Several questions still remain, including: Why might the timing of these relationships be different for the two groups? It is possible that it takes a higher level of language for the ASD children for this relationship between input and child language to emerge. Another possibility is that it may take a certain amount of therapy for the ASD children to gain the necessary skills to attend to the input. The therapy the children with autism are receiving may be providing a linguistic foundation, or it may be providing crucial attentional skills, or it may be improving their processing skills. Another possibility is that maturation is playing a role. There may be other skills that have yet to fully mature for our children with autism despite having equivalent language at these time points to their “language-matched” counterparts in the typically developing group. In conclusion, although many questions remain, this study has provided us with useful information about the relationships between maternal input and child language for children with autism. We were able to replicate several findings
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