Reading outcomes of children with delayed early vocabulary : A follow-up from age 2–16

This is a self-archived version of an original article. This version may differ from the original in pagination and typographic details. Author(s): Title: Year: Version: Copyright: Rights: Rights url: Please cite the original version: CC BY-NC-ND 4.0 https://creativecommons.org/licenses/by-nc-nd/4.0/ Reading outcomes of children with delayed early vocabulary : A follow-up from age 2–16 © 2018 Elsevier Ltd. All rights reserved. Accepted version (Final draft) Psyridou, Maria; Eklund, Kenneth; Poikkeus, Anna-Maija; Torppa, Minna Psyridou, M., Eklund, K., Poikkeus, A.-M., & Torppa, M. (2018). Reading outcomes of children with delayed early vocabulary : A follow-up from age 2–16. Research in Developmental Disabilities, 78, 114-124. https://doi.org/10.1016/j.ridd.2018.05.004 2018 EARLY VOCABULARY DELAY: FOLLOW-UP IN READING 1 Running head: EARLY VOCABULARY DELAY: FOLLOW-UP IN READING Reading Outcomes of Children with Delayed Early Vocabulary: A Follow-up from Age 2 to 16. Maria Psyridoua University of Jyväskylä, Finland Kenneth Eklundb University of Jyväskylä, Finland Anna-Maija Poikkeusc University of Jyväskylä, Finland Minna Torppad University of Jyväskylä, Finland aDepartment of Teacher Education, Faculty of Education and Psychology, University of Jyväskylä, Finland, P.O.Box 35, Ruusupuisto, Alvar Aallon katu 9, 40014-FIN. E-mail: [email protected] bDepartment of Psychology, Faculty of Education and Psychology, University of Jyväskylä, Finland, P.O.Box 35, Kärki, Mattilanniemi 6, 40014-FIN. E-mail: [email protected] EARLY VOCABULARY DELAY: FOLLOW-UP IN READING 2 cDepartment of Teacher Education, Faculty of Education and Psychology, University of Jyväskylä, Finland, P.O.Box 35, Ruusupuisto, Alvar Aallon katu 9, 40014-FIN. E-mail: anna- [email protected] dDepartment of Teacher Education, Faculty of Education and Psychology, University of Jyväskylä, Finland, P.O.Box 35, Ruusupuisto, Alvar Aallon katu 9, 40014-FIN. E-mail: [email protected] Psyridou, M., Eklund, K., Poikkeus, A.-M., Torppa, M. (2018). Reading outcomes of children with delayed early vocabulary: A follow-up from age 2-16. Research in Developmental Disabilities. doi: 10.1016/j.ridd.2018.05.004 EARLY VOCABULARY DELAY: FOLLOW-UP IN READING 3 Abstract Background Delays in expressive vocabulary have been associated with lower outcomes in reading. Aim The aim is to conduct a long-term follow-up study to investigate if early expressive vocabulary delay (late talking) predicts reading development in participants age 16 and under. We examine further if the prediction is different in the presence of family risk for dyslexia (FR) and early receptive vocabulary delay. Methods Expressive and receptive vocabulary skills were assessed at the age of 2‒2.5 years, and reading skills in Grades 2, 3, 8 and 9 (age 8 to 16). The longitudinal sample consisted of 200 Finnishspeaking children, of which 108 had FR for dyslexia and 92 came from families without reading difficulties. We compared the reading development of five subgroups: 1) FR and no vocabulary delay; 2) FR and late talkers, 3) FR, late talkers and co-existing receptive vocabulary delay; 4) no FR and late talkers; and 5) no FR and no vocabulary delay. Results The group with FR and expressive and receptive vocabulary delay had difficulties in reading comprehension, but not in reading fluency. The late talkers without receptive vocabulary difficulties tended to become typical readers. Conclusions and Implications Delays in early vocabulary can lead to a reading comprehension deficit, with the specification that expressive vocabulary deficit alone can alleviate in time, whereas the combined deficit is a stronger risk marker. EARLY VOCABULARY DELAY: FOLLOW-UP IN READING 4 Keywords: expressive vocabulary; receptive vocabulary; reading fluency; reading comprehension; reading difficulties What this paper adds? The present study extends the literature by investigating the reading development of children with early expressive vocabulary delay followed up to age 16 (Grade 9) in a Finnish language context in relation to both reading fluency and reading comprehension. In addition, we examine whether this relationship is different in the presence and absence of other co-occurring risk factors, in particular family risk for dyslexia and early receptive vocabulary delay. The existing literature on reading development of children with delays in early vocabulary is almost exclusively limited to findings concerning the early grades of primary school. Furthermore, all the previous studies spanning beyond Grade 2 have been conducted using English-speaking children; thus, further research in other orthographies is needed. We compared the reading development of five subgroups: 1) FR and no vocabulary delay; 2) FR and late talkers; 3) FR, late talkers and co-existing receptive vocabulary delay; 4) no FR and late talkers; and 5) no FR and no vocabulary delay. Our findings add to the literature by suggesting that a trajectory of later reading comprehension difficulties is much more likely when early expressive vocabulary delay is accompanied by receptive vocabulary delay. Our findings suggest that a delay in early vocabulary can lead to a persistent deficit with the specification that expressive vocabulary deficit alone can be alleviated in time, whereas the combined deficit is a stronger risk marker. Early expressive vocabulary delay represented high risk only for reading comprehension development and only when it co-occurred with other risk factors (family risk for dyslexia and receptive vocabulary difficulties). EARLY VOCABULARY DELAY: FOLLOW-UP IN READING 5 Reading outcomes of children with delayed early vocabulary: A follow-up from age 2 to 16 1. Introduction Early years expressive language delay, or late talking, is one of the most common concerns of parents and early health care personnel, and it is one of the common reasons for referring young children for evaluation. This is not surprising, as early language development forms the foundation for later educational and academic achievement and has important links with social adaptation (Reilly et al., 2010). From a clinical and educational perspective, it is important to be able to predict as early as possible which children may be at risk for learning difficulties in their school years. Delays in expressive vocabulary have been associated with lower outcomes in reading (Rescorla, 2002, 2005, 2009), but apart from Rescorla’s sample from the USA, little research has focused on literacy development after the early grades of primary school using longitudinal designs. Moreover, most of the previous studies have been conducted among English-speaking children and have focused almost solely on early expressive, but not receptive vocabulary. The present study will extend previous studies (Duff, Reen, Plunkett, & Nation, 2015; Lyytinen, Eklund, & Lyytinen, 2005; Rescorla, 2002, 2005, 2009) to later years of schooling by examining if late talking (delays in early expressive vocabulary) predict reading development (fluency and comprehension) from early primary Grades 2 and 3 to lower secondary Grades 8 and 9 in Finland. We will also examine the effects of co-occurring receptive vocabulary delay and family risk for dyslexia on the relationship between early vocabulary skills and reading outcomes. Expressive vocabulary may not be a marker of subsequent language and literacy difficulties when it is not accompanied by co-occurring difficulties in receptive vocabulary (Lyytinen et al., 2005). It is also possible that family risk EARLY VOCABULARY DELAY: FOLLOW-UP IN READING 6 for dyslexia actually explains the link between expressive vocabulary delay because the children with family risk (due to parental language or reading difficulties) are shown to be at risk for both vocabulary delays (Duff et al., 2015; Lyytinen et al., 2005; Snowling, Gallagher, & Frith, 2003; Snowling, Muter, & Carroll, 2007) and for later language and reading outcomes (Lyytinen, et al., 2005; Reilly et al., 2010). Early vocabulary skills (expressive or a composite score of expressive and receptive vocabulary) have been shown to be associated with both reading fluency (Nation & Snowling, 2004; Snowling et al., 2003) and reading comprehension (Duff et al., 2015; Nation, Cocksey, Taylor, & Bishop, 2010; Ouellette 2006; Ouellette & Beers 2010). Theories on how early vocabulary skills and reading outcomes are linked depend, however, on the reading skill in question. According to the lexical restructuring hypothesis, the link between early vocabulary and reading fluency is indirect and mediated via phonological skills (e.g. Walley, Metsala, & Garlock, 2003). Phonological awareness plays a critical role in the development of decoding (Ehri et al., 2001; Hulme & Snowling, 2014; Melby-Lervåg, Lyster, & Hulme, 2012), and tasks requiring identification or manipulation at the phoneme level, in particular, have been found to be associated with variations in decoding skills (Georgiou, Parrila, & Papadopoulos, 2008; Lervåg, Bråten, & Hulme, 2009). Walley et al. (2003) suggested that phonological awareness may be linked to vocabulary via the process of restructuring phonological representations (the word cat, for example, first segmented at syllable level /k/-/æt/ becoming segmented at phoneme level /k/-/æ/-/t/). Vocabulary growth increases sensitivity towards phonological similarities between words, which elicits a restructuring of the already-existing phonological representations in the lexicon (Walley et al., 2003). The link between reading comprehension and vocabulary skills may be more direct than that of vocabulary and reading fluency. According to the simple view of reading model (Gough & Tunmer, 1986; Hoover & Gough, 1990), reading comprehension is based on two core skills: EARLY VOCABULARY DELAY: FOLLOW-UP IN READING 7 decoding and language comprehension. Reading comprehension has been shown to rely on a variety of oral language comprehension skills (Hulme & Snowling, 2014), including expressive and receptive vocabulary (e.g. Nation et al., 2010) and listening comprehension (e.g. Catts, Adlof, & Weismer, 2006; Nation et al., 2010). Weaknesses in these skills have been found to be manifested before learning to read, thus providing a possible causal link between the influence of oral language comprehension on difficulties in reading comprehension (e.g. Catts et al., 2006; Nation et al., 2010). This association between vocabulary and reading comprehension has also been shown through intervention studies (Clarke, Snowling, Truelove, & Hulme, 2010; Fricke, Bowyer-Crane, Haley, Hulme, & Snowling, 2013). The vast majority of studies on the reading development of children with expressive vocabulary delay have focused on language outcomes in kindergarten (age range between 2 and 5.5 years) (Feldman et al., 2005; Moyle, Weismer, Evans, & Lindstrom, 2007; Thal, Miller, Carlson, & Vega, 2005) or reading outcomes in the early grades of primary school (Grade 2) (Lyytinen et al., 2005). The documentation on the reading development of the children with expressive vocabulary delay beyond the early grades comes from one sample (Rescorla, 2002, 2005, 2009). Rescorla (2002) showed that children that had been identified as having expressive vocabulary delay in early childhood continued to manifest significantly poorer reading skills (i.e., decoding, comprehension, written language and spelling) than their peers at the ages of 8 and 9. At the age of 13, the children with expressive vocabulary delay demonstrated significantly lower vocabulary and reading comprehension skills than the comparison children (Rescorla, 2005), whereas no differences were observed in reading fluency (Rescorla, 2005). At the age of 17, the children with expressive vocabulary delay had average reading skills but below average vocabulary and verbal memory (Rescorla, 2009). Rescorla’s findings show that early expressive vocabulary delay is negatively associated with reading achievement, especially after the initial stages of learning to read (Rescorla 2002, 2005, EARLY VOCABULARY DELAY: FOLLOW-UP IN READING 8 2009), and the effect is primarily seen on reading comprehension rather than reading fluency (Rescorla, 2005, 2009). Rescorla, however, did not control for other risk factors or co-occurring difficulties, and it is possible that late talking is not the cause of subsequent reading difficulties. A few studies show that expressive vocabulary delay may actually be a risk factor for reading development only when accompanied by other risk factors, such as family risk for dyslexia or language difficulties and receptive vocabulary delays (Duff et al., 2015; Lyytinen et al., 2005; Poll & Miller, 2013). Family risk for dyslexia is linked to both vocabulary and reading difficulties and may be the underlying cause for late talkers’ problems in reading (Duff, et al., 2015; Lyytinen, et al., 2005; Snowling, et al., 2003; Snowling, et al., 2007; Torppa, Lyytinen, Erskine, Eklund, & Lyytinen, 2010). It has been shown that the combination of family risk for reading difficulties and early delays in expressive and receptive vocabulary impedes reading development in the early grades (Duff et al., 2015; Lyytinen et al., 2005). In the same Finnish sample that is used for this study, Lyytinen et al. (2005) showed that those children with expressive vocabulary delay at the end of the second grade (age 8 years) who also exhibited evidence of receptive vocabulary delay and a family risk for dyslexia were often diagnosed as manifesting reading difficulties, whereas those children with only expressive vocabulary delay were not. We add to their findings by extending the investigation to Grades 3, 8 and 9 and by examining both reading fluency and reading comprehension development from Grade 2 to 9. 2. The Present Study The existing literature on reading development of children with delays in early vocabulary is almost exclusively limited to findings concerning the early grades of primary school, and all the studies except one (Lyytinen et al., 2005) have been conducted using English-speaking children. The present study extends the literature by investigating the reading development of EARLY VOCABULARY DELAY: FOLLOW-UP IN READING 15 divide late talkers (i.e., children identified with expressive vocabulary delay) into groups with and without receptive vocabulary delay. Of the five subgroups, three were with family risk and two with no family risk: 1) family risk and no vocabulary delay (FR); 2) family risk and late talkers (FR-LT1); 3) family risk, late talkers and receptive vocabulary delay (FR-LT2); 4) no family risk and late talkers (NR-LT1), and 5) no family risk and no vocabulary delay (NR). There were two groups of late talkers (FR-LT1 and NR-LT1) who had only expressive vocabulary delay. They had expressive vocabulary score at least one standard deviation below the mean of children in the control group but age-appropriate receptive skills. There were 10 children with family risk for dyslexia (FR-LT1) and 10 children with no risk for dyslexia (NRLT1). The second subtype of late talkers demonstrated both an expressive and receptive vocabulary delay (at least one standard deviation below the mean on both scores). There were 12 children from the family risk sample (FR-LT2), but only three children from the no-risk sample fulfilled these criteria, and they were subsequently excluded from the analyses. Finally, the analyses involved two groups with no vocabulary delay: the FR group (N = 83) and the NR group (N = 79) with age-appropriate or better early expressive and receptive vocabulary. In addition to the group comparisons, we also examined the correlations between all measures. The descriptive statistics of the measures used in the identification of the five groups are presented in Table 1. Three children of the family risk sample were not included in the analysis because the Reynell expressive and receptive scores were missing for two of them and because one of the children attended school one year later than his age-mates and we did not have his reading measure outcomes. None of the children had reports on Specific Language Impairment (SLI) diagnoses at any age. In Finland, physicians use the International Classification of Diseases (ICD) when diagnosing specific language impairment (SLI) (Asikainen, 2005). However, some milder language or language-related difficulties were diagnosed in 11 children (one had naming difficulty, five demonstrated delayed EARLY VOCABULARY DELAY: FOLLOW-UP IN READING 16 language/speech development, four had dysphasic features, and one faced learning difficulties, especially in language). Of these 11 children, six belonged to the group with family risk and both expressive and receptive vocabulary delays (FR-LT2); three belonged to the group with family risk, but no early vocabulary delays (FR); and two belonged to the control group with expressive vocabulary delay (NR-LT1). 4. Results 4.1 Group Differences in Reading Fluency The one-way ANOVAs for reading fluency showed significant group differences in Grades 2, 3 and 8 (Table 2, Table 3, Figure 1). Pairwise comparisons (LSD) revealed that in Grades 2 and 3 the NR group children were faster readers than the FR group children. In grade 3, the NR group children were also faster readers than the FR-LT2 group children. In Grade 8, the pairwise comparisons (Dunnett T3) showed that the NR group children were faster readers than the FR group children. Further inspection of the effect sizes showed that the comparisons between the three groups with family risk for dyslexia and the two groups without family risk for dyslexia all had small to medium effect sizes. 4.2 Group Differences in Reading Comprehension The one-way ANOVAs for reading comprehension showed significant group differences in Grades 2 and 9, but not in Grade 3 (Table 2, Table 3, Figure 2). In Grade 2, the pairwise comparisons (Dunnett T3) showed no significant differences between the groups but the effect sizes were large in favour of the NR group compared to the FR-LT2 and NR-LT1. In Grade 3, the pairwise comparisons (LSD) suggested that children in the FR-LT2 group were poorer comprehenders than children in the FR, FR-LT1 and NR groups. The effect sizes were medium for the FR-LT2 comparison with FR and large in comparison with the FR-LT1 and NR groups. In Grade 9, the pairwise comparisons (LSD) showed lower reading comprehension scores for EARLY VOCABULARY DELAY: FOLLOW-UP IN READING 17 the FR-LT2 group than for all the other groups, and these differences were accompanied by large effect sizes. 4.3 Correlations between Early Expressive and Receptive Vocabulary and Literacy Measures Correlations (Table 4) showed that expressive and receptive vocabulary measures were strongly associated. Both expressive and receptive vocabulary had stronger correlations with reading comprehension than reading fluency. The correlations were non-significant between the vocabulary measures and Grade 8 reading fluency. In contrast, the correlations between expressive and receptive vocabulary and reading comprehension were statistically significant across all grades. 5. Discussion The reading outcomes of children with expressive vocabulary delay were investigated in this study by analyzing their reading development up to 16 years of age using measures of both reading fluency and comprehension. The role of the additional risk factors of family risk for dyslexia and poor early receptive vocabulary were also examined. Five subgroups were identified based on children’s early expressive vocabulary, receptive vocabulary and family risk status, and they were compared in reading fluency and comprehension measures in Grades 2, 3, 8 and 9. In general, the findings suggest that early expressive language delay predicts reading comprehension, but not reading fluency development. Late talking alone was not, however, a sufficient risk index for reading comprehension difficulties for children with family risk for dyslexia or for children without such risk. Only the children with both expressive and receptive vocabulary delays and family risk had clear difficulties in reading comprehension, and the difficulties were sustained to adolescence. EARLY VOCABULARY DELAY: FOLLOW-UP IN READING 18 The children who had delays in both expressive and receptive vocabulary as toddlers demonstrated persistent weaknesses in comparison to the other groups in reading comprehension measures. As indicated by moderate to large effect sizes, these children had lower scores compared to all the other groups at the end of Grade 2 and 3, and they continued on a declining trajectory to the end of Grade 9. Although the comparison between all the groups in Grade 3 did not reveal statistically significant differences, the differences were clear in pairwise comparisons and in the effect sizes of the group comparisons, which become larger from Grade 3 onwards. All the groups except FR-LT2 performed at a similar level in Grade 3. Our findings add to the literature (Duff et al., 2015; Lyytinen et al., 2005; Rescorla, 2002, 2005, 2009) by suggesting that a trajectory of later reading comprehension difficulties is much more likely if early expressive vocabulary delays are accompanied by receptive vocabulary delays. In our sample, the children with both receptive and expressive vocabulary delay also had family risk for dyslexia, which makes it difficult to separate the effects of family risk and receptive vocabulary delay. However, because the other family risk children (the group who did not have a vocabulary delay and the group who had only an expressive delay) manifested average reading comprehension, it can be assumed that it is the combined vocabulary difficulty (expressive and receptive), rather than family risk per se, that underlies reading comprehension difficulties. Moreover, the fact that the combination of receptive and expressive vocabulary delays was more common in the family risk group (12 children) than in the no-risk group (only three children) suggests a link between family risk for reading difficulties and combined vocabulary delay. The findings suggest that a delay in early vocabulary can lead to a reading comprehension deficit, which is in line with suggestions in the previous studies (Duff et al., 2015; Lyytinen et al., 2005; Rescorla, 2005, 2009), with the specification that an expressive vocabulary deficit alone can be alleviated in time, whereas the combined deficit is a stronger EARLY VOCABULARY DELAY: FOLLOW-UP IN READING 19 risk marker. Previous studies have also shown correlative evidence for the predictive association between language skills and reading comprehension (Catts et al., 2006; Duff et al., 2015; Nation et al., 2010). The present findings are in line with Rescorla’s (2005) findings indicating that children with delays in early vocabulary demonstrated no differences in basic reading mechanisms (including fluency) at age 13, but they had significantly lower scores in reading comprehension. In addition, they are in line with the findings of Duff et al. (2015) suggesting that early vocabulary (in their study combination of expressive and receptive) has a stronger relationship with reading comprehension than reading accuracy. Because early vocabulary was measured at the age of 2–2.5 years in the present study, which was long before reading had started to develop and which prevented any concerns about the direction of effects, a predictive association between early vocabulary and reading comprehension outcomes could be suggested. This link between reading comprehension and early vocabulary could be explained by the simple view of reading model (Gough & Tunmer, 1986; Hoover & Gough, 1990). Reading comprehension has been shown to rely on a variety of oral language comprehension skills (Hulme & Snowling, 2014), including expressive and receptive vocabulary (e.g. Nation et al., 2010) and listening comprehension (e.g. Catts et al., 2006; Nation et al., 2010). Weaknesses in these skills have been found to be manifested before learning to read, which could provide a possible causal link between the influence of oral language comprehension on difficulties in reading comprehension (e.g. Catts et al., 2006; Nation et al., 2010). In contrast to reading comprehension, reading fluency was found to be linked with family risk for dyslexia and not with the presence of early expressive vocabulary delay. The finding that family risk was predictive of reading fluency was expected and supports previous studies indicating the strong effects of family risk in developmental dyslexia (Lyytinen et al., 2015; Snowling et al., 2003; van Bergen et al., 2012). Based on our findings, it is thus likely EARLY VOCABULARY DELAY: FOLLOW-UP IN READING 20 that children with reading difficulties who show early vocabulary difficulties have additional risk factors, such as family risk (Nation & Snowling, 2004; Snowling et al., 2003; Torppa et al., 2010). The finding of no link from late talking to reading fluency development appears to contradict the lexical restructuring hypothesis (e.g. Walley et al., 2003), which suggests a link between early vocabulary and reading fluency mediated via phonological skills. In addition, we have shown earlier in this same sample that early vocabulary is linked via phonological skills to kindergarten precocious reading ability (Torppa et al., 2007), supporting the lexical restructuring hypothesis. However, in the present study, we focused on a phase in reading development where phonological skills may not be strong predictors of reading fluency anymore, at least in the context of a transparent orthography (see e.g. Aarnoutse, van Leeuwe, & Verhoeven, 2005; Georgiou, Torppa, Manolitsis, Lyytinen, & Parrila, 2012). Thus, the mediated effect from vocabulary also ceases to exist. In the English language context, phonological processing is a strong predictor of reading for a longer time (e.g. Gallagher, Frith, & Snowling, 2000; Torgesen, Wagner, & Rashotte, 1994). In line with this, our results for the early grades show differences only in reading comprehension, while the studies from the English language context report differences in various reading skills (Duff et al., 2015; Rescorla, 2002). In later grades, however, our results are similar to the findings in English language context studies (Rescorla, 2005, 2009). It seems that the transparency of the orthography affects the speed of decoding development (e.g. Ellis et al., 2004; Seymour et al., 2003) and the importance of phonological processing in the development. Consequently, the mediated impact of expressive and/or receptive vocabulary delay via phonological processing to reading skills may thus be broader and may be sustained longer in the less transparent orthographies. EARLY VOCABULARY DELAY: FOLLOW-UP IN READING 21 The limitations in this study include its small sample size and the inclusion of only one reading comprehension measure at each age. Analyses with a larger sample size would have more statistical power. However, samples with extensive assessments and such a long followup are rare and provide unique information. Further, it was not possible to identify a large enough group with difficulties in both expressive and receptive vocabulary but no family risk, which would have been informative. In addition, it would have been interesting to know how these children scored in expressive and receptive vocabulary at adolescence and whether the early language difficulties experienced persisted and co-occurred with literacy skills in adolescence. Based on the findings by Rescorla (2005, 2009), we expect that this is the case, but unfortunately, we could not examine the issue due to the lack of such data in our sample. Moreover, data on family risk for reading comprehension or language skills would have been an interesting addition. In conclusion, the findings indicate that the reading trajectories of late talkers depended on the co-occurrence of other risk factors and on the nature of the reading outcome in question. Early expressive vocabulary delay represented a high risk only for reading comprehension development and only when it co-occurred with other risk factors (family risk for dyslexia and receptive vocabulary difficulties). Late talking without receptive vocabulary difficulties did not increase the risk for reading difficulties among either group (family risk or no family risk). Our results indicate that in addition to expressive vocabulary delay, it is critical to recognize a delay in receptive skills as an early risk factor, since a delay in only expressive vocabulary is not informative enough to predict school age reading development. Based on the findings of the present study and those by Rescorla (2002, 2005, 2009), it is suggested that children with expressive vocabulary delay (especially those with family risk for dyslexia and receptive vocabulary delay as additional risk factors) should be provided extra support (e.g. exposure to language games and book reading). Finally, based on the results of the present study and those EARLY VOCABULARY DELAY: FOLLOW-UP IN READING 22 of previous studies, we suggest that the effects of receptive vocabulary should be examined more in depth, since all the studies so far have used a combination of expressive and receptive vocabulary delays. In addition, certain protective factors could lead to cognitive and socioemotional resilience and influence the reading outcomes of children with reading difficulties. Based on the current findings, one potential protective cognitive skill may be receptive vocabulary. In line with the results of the study conducted by Haft, Myers and Hoeft (2016), we propose that future studies include investigations of the factors that contribute to the resilience of students who have reading difficulties or who are at risk of developing them. Funding Funding for this research was received from funding agencies in the public and not-for-profit sectors over the years. 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Journal of Educational Psychology, 100(3), 566–580. doi:10.1037/0022-0663.100.3.566 EARLY VOCABULARY DELAY: FOLLOW-UP IN READING 31 Table 1 Descriptive statistics for the vocabulary measures used to determine the subgroups Family risk, no language delay (FR) (N=83) Family risk, Late talkers (FR-LT1) (N=10) Family risk, Late talkers and receptive language delay (FR-LT2) (N=12) No family risk, Late talkers (NR-LT1) (N=10) No family risk, no language delay (NR) (N=79) M SD M SD M SD M SD M SD F df 2 years Vocabulary production (CDI) 305.92 135.79 57.70 39.81 87.25 72.88 33.10 39.24 321.36 138.50 Maximum sentence length (CDI) 5.67 2.24 2.10 1.12 2.70 1.47 1.63 1.30 6.47 2.67 Bayley expressive vocabulary 10.32 3.51 1.40 1.95 3.18 3.52 1.10 2.33 10.97 2.89 2.5 years Reynell Receptive Language Scale 37.072 6.07 36.502 2.27 26.751 3.86 36.402 2.99 37.912 5.83 10.40 4,184*** Reynell Developmental Language Scale 36.05 5.00 28.50 2.84 24.08 5.23 22.60 8.47 35.87 4.55 Composite score for expressive vocabulary .152 .57 -1.311 .17 -1.271 .49 -1.631 .46 .282 .58 56.44 4,189*** Notes: Groups with different subscripts (1,2) differed from each other in post-hoc comparisons, using LSD. The composite score for expressive vocabulary was calculated as average of the standardized scores for the a) Vocabulary production, b) Maximum sentence length, c) Bayley expressive vocabulary and d) Reynell Developmental Language Scale. Standardized scores are based on the distribution of the control group. EARLY VOCABULARY DELAY: FOLLOW-UP IN READING 32 The five groups (FR, FR-LT1, FR-LT2, NR-LT1, NR) were identified with respect to status of expressive and receptive vocabulary delay and family risk for dyslexia. The FR-LT1 (N=10) and the NR-LT1 (N=10) groups had at least 1 SD below the mean of children in the control group in the composite score of expressive vocabulary but age-appropriate receptive skills. The FR-LT2 (N=12) group demonstrated both an expressive and receptive vocabulary delay (at 1 SD below the mean on both scores). The FR (N=83) and the NR (N=79) groups had age-appropriate or better early expressive and receptive vocabulary. *p≤.05, **p≤.01. ***p≤.001 EARLY VOCABULARY DELAY: FOLLOW-UP IN READING 33 Table 2 Descriptive statistics and group comparisons for the reading measures FR FR-LT1 FR-LT2 NR-LT1 NR M SD M SD M SD M SD M SD F df Grade 2 Reading Fluency z -.261 .95 -.181,2 1.05 -.191,2 .98 .211,2 1.01 .362 .95 4.40** 4,185 Reading comprehension 8.99 3.00 8.44 2.92 6.55 3.33 7.00 2.55 9.77 1.79 5.27*** 4,166 Grade 3 Reading fluency z -.221 .98 -.281,2 1.25 -.321 .93 .051,2 1.30 .332 .90 3.72** 4,189 Reading comprehension 9.761 1.76 10.201 1.32 8.642 2.01 10.001,2 2.78 10.151 1.40 2.12 4,170 Grade 8 Reading fluency z -.231 1.13 -.281,2 .96 -.221,2 .85 -.031,2 1.55 .372 .68 3.95** 4,174 Grade 9 Reading comprehension .121 .79 -.171 .73 -1.142 1.12 -.151 1.09 .251 .90 5.91*** 4,153 Notes: Groups with different subscripts (1,2) differed from each other in post-hoc comparisons, using either LSD or Dunnett T3, depending on equality of the variances. Subscript z refers to standardized score. The reading fluency measures are composite scores calculated as average of the standardized scores for the three reading fluency tasks. Standardized scores are based on the distribution of the control group. *p≤.05, **p≤.01. ***p≤.001 EARLY VOCABULARY DELAY: FOLLOW-UP IN READING 34 Table 3 Effect sizes for group comparisons in reading fluency and reading comprehension Effect sizea FR vs FR-LT1 FR vs FR-LT2 FR vs NR-LT1 FR vs NR FR-LT1 vs FR-LT2 FR-LT1 vs NR-LT1 FR-LT1 vs NR FR-LT2 vs NR-LT1 FR-LT2 vs NR NR-LT1 vs NR Grade 2 Reading fluency .08 .07 .50 .65 .01 .38 .54 .40 .57 .15 Reading comprehension .19 .77 .72 .31 .60 .53 .55 .15 1.20 1.26 Grade 3 Reading fluency .05 .10 .23 .58 .04 .26 .56 .33 .71 .25 Reading comprehension .29 .60 .10 .25 .92 .09 .04 .56 .88 .07 Grade 8 Reading fluency .05 .01 .15 .64 .07 .19 .78 .15 .77 .33 Grade 9 Reading comprehension .37 1.30 .30 .16 1.03 .02 .51 .90 1.37 .40 Note: Large (>.80) effect size with bold a The value of Cohen’s d was calculated using the means and standard deviations of two groups. Cohen d is considered large when d>.80, medium when d>.50 and small when d>.30 EARLY VOCABULARY DELAY: FOLLOW-UP IN READING 35 Table 4 Correlation table for expressive and receptive vocabulary and reading fluency and reading comprehension in grades 2, 3, 8, and 9. 1. 2. 3. 4. 5. 6. 7. 1. Expressive vocabulary 2. Receptive vocabulary .49*** 3. Reading fluency, Grade 2 .16* .18* 4. Reading fluency, Grade 3 .20** .23** .89*** 5. Reading fluency, Grade 8 .11 .12 .71*** .79*** 6. Reading comprehension, Grade 2 .39*** .34*** .48*** .44*** .40*** 7. Reading comprehension, Grade 3 .19* .26*** .35*** .36*** .38*** .45*** 8. Reading comprehension, grade 9 .32*** .30*** .29*** .40*** .33*** .37*** .45*** *p≤.05, **p≤.01. ***p≤.001 EARLY VOCABULARY DELAY: FOLLOW-UP IN READING 36 Figure 1 Development of fluency skills by group for each grade EARLY VOCABULARY DELAY: FOLLOW-UP IN READING 37 Figure 2 Development of comprehension skills by group for each grade