AEROTERMO TECNA CFS

Receptive and Expressive Vocabulary Breadth. In terms of performance at t1, the monolingual group exhibited significant advantages on both measures of vocabulary breadth knowledge. De- spite this, the absolute difference in the raw number of correctly identified words by the monolin- gual group was relatively small, at 7.94 for receptive and 3.77 for expressive knowledge. Effect sizes for group differences at t1 were modest, at g = 0.51 for receptive and g = 0.56 for expres- sive knowledge, respectively. Standardised scores revealed that both groups were performing within the average to below-average range on measures of vocabulary breadth (Receptive means - Mono: 87.80; EAL: 80.13; expressive means – Mono: 8.91; EAL: 7.35; somewhat below expec- tations relative to norming populations of the BPVS and CELF EV).

The monolingual group advantage in vocabulary knowledge breadth found here is supported by other studies of similarly-aged bilingual learners in England and other countries (Babayi ˘git, 2014a, 2015; Beech & Keys, 1997; Burgoyne et al., 2009, 2011a; Droop & Verhoeven, 2003; Hutchinson et al., 2003; Limbird et al., 2014; Mahon & Crutchley, 2006). However, these studies tend to report group differences of larger magnitude than those found here, for instance: d = 1.5 to 2.17 in Hutchinson et al. (2003) using the Test of Word Knowledge; d = 1.93 to 2.62 in Droop and Verhoeven (2003) using a Dutch-language multiple-choice breadth measure; and d = 2.18 to 2.54 in Lervåg and Aukrust (2010) using the PPVT. However, even the relatively more modest effect sizes found in studies of EAL learners in England, including those using the BPVS, of between d = 0.75 and 1.12 (Babayi ˘git, 2014a; Burgoyne et al., 2009, 2011a; Mahon & Crutchley, 2006) are higher than the magnitude of those found in the present study, which did not rise above g = 0.71 for any vocabulary measure at any time point.

One reason for this discrepancy may be the matching of the two groups in the present study on amount of English language instruction, a strategy not typically employed in other U.K.-based studies of EAL learners. However, it should be noted that 9 to 10 year-old EAL learners in Babay- i ˘git (2014a) similarly had a minimum of four years of English-medium instruction, and yet signif- icantly underperformed in relation to their monolingual peers on the BPVS by a magnitude of d = 1.12. One alternative reason for this discrepancy may be the extent to which the monolingual comparison group underperformed in relation to the norming population of the BPVS: in other words, had the monolingual group scored closer to the norming population average (i.e. a stan- dard score of 100), the magnitude of the group difference in receptive vocabulary knowledge may have been larger, and therefore more akin to that reported by studies alluded to above. Indeed, the monolingual group did perform in the (low) average range (with a mean raw score of 103 relating to a standard score of 87.80 at t1). Once again, however, comparison with the results of Babayi ˘git (2014a) poses a challenge to this conclusion. To aid interpretation, Table 4.22 below contrasts group mean raw scores, standard deviations, and effect sizes for the results of Babayi ˘git

(2014a) and t3 of the present study, when participants in both studies were aged 9 to 10 years old.

Table 4.22: Comparison of Monolingual-EAL Group Discrepancies on the BPVS (Raw Scores)

Monolingual EAL Effect Size t3 of the present study 116.76 110.84 0.38

(13.77) (16.76)

Babayi ˘git (2014a) 100.45 83.28 1.12

(14.15) (16.36)

Note: Effect size in g for present study and d for Babayi ˘git (2014a)

It can be seen here that the relatively larger discrepancy in group performance in Babayi ˘git (2014a) appears to be due to the particularly low performance of the EAL group, which scored on average around 17 raw scores lower than the monolingual group, in contrast to a group dis- crepancy of around 6 raw scores in the present study. Another striking difference here is the relatively higher score of the monolingual group in the present study relative to that in Babayi ˘git (2014a). Therefore, lower than expected performance of the monolingual group in this study as a cause of relatively smaller monolingual-EAL group discrepancies in vocabulary performance is not supported. Rather, it would appear that the relatively more similar performance between the two groups in the present study is due to the higher than expected performance of the EAL group relative to the pattern reported in Babayi ˘git (2014a). Unfortunately, such comparisons with other measures in the battery are not permitted due to use of different measures and age cohorts.

Expressive Vocabulary Depth. Although the monolingual group did exhibit an advantage in vocabulary depth at t1, the magnitude of this trend was smaller than for vocabulary breadth mea- sures (g = 0.27) and did not reach statistical significance. Reference to scaled scores revealed that both groups scored within the average range (Mono: 9.70; EAL: 8.90). Again, the absolute difference in the raw number of points scored by the monolingual group was small, at 1.86. To some extent the lack of a significant group difference may be due to the particular measure em- ployed, as the WISC VC has a very limited scoring range of 0 to 2 and therefore may have been insensitive to finely detailed knowledge12_{. Therefore, in order to test the robustness of these find-}

ings, children’s responses on the WISC VC subtest at t1 were subjected to an alternative scoring method emanating from the intervention study in Chapter 6. On this measure, examinees receive a score from 0 to 8 for each stimulus word they are asked to define (for a full description of this measure, see Section 6.9.1 on page 195). Points are awarded across four categories of knowl- edge, including a straightforward definition, background knowledge (related concepts or personal experiences), lexical knowledge (synonyms, related words and phrases), and non-verbal (for ex- ample, gesturing a circular motion for the word island ). Statistics for group performance and comparisons on this measure are provided in Appendix 4.3 on page 271. Despite the use of this supposedly more sensitive measure, the two groups still did not differ significantly in total score (F (80,1) = 0.00, p = .985), although monolingual children did make significantly more use of back-

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While many children indicated some level of understanding of the target words, their responses were not always acknowledged by the scoring criteria. For example, when asked ’What is a pest? one child responded, ’pest is a word used by adults to describe children’, which received a score of 0 according to the scoring guidelines but nevertheless did indicate some level of knowledge.

ground knowledge in their responses (F (80,1) = 5.93, p = .017). While this generally points to a level of similarity between the two scoring procedures, it must be noted that in the bespoke word knowledge assessment, examinees are also required to use target vocabulary in a sen- tence, thus providing estimates of receptive as well as productive knowledge unlike the WISC VC which focuses exclusively on meaning rather than use (Nation, 2001). Nevertheless, results from the application of this bespoke scoring rubric bear similarity to Vermeer (2001), in which young mono- and bilingual children did not differ significantly in their vocabulary depth knowledge once credit was awarded for nonverbal and exemplar responses.

There is some research to support the existence of monolingual advantages in vocabulary depth. For example, Lervåg and Aukrust (2010) found large monolingual advantages on two separate measures of vocabulary depth knowledge in a large sample of 7 year-olds in Norway of between d = 1.35 and 1.59. Similarly, in a vocabulary definition task with 8 year-olds in the Netherlands, Droop and Verhoeven (2003) found monolingual advantages of a similar magnitude, ranging from d = 1.38 to 1.85. These studies present a striking contrast to the magnitude of the monolingual advantage found in vocabulary depth knowledge in the present study of just g = 0.27. This discrepancy is potentially due to differences not only in assessments used (although Lervåg and Aukrust did also made use of the WISC VC), but also to crucial differences in the samples of children recruited; specifically, by age 7, participants in Lervåg and Aukrust (2010) had only just begun formal instruction, and 8 year-old participants in Droop and Verhoeven (2003) were re- cruited specifically from very low-SES backgrounds. In contrast, the children in the present study had been in receipt of formal instruction since at least Year 1, and although recruited from schools in neighbourhoods of slightly higher than average social deprivation, this did not approximate the same level of deprivation described in the latter study.

Taken together, these findings suggest that the word knowledge of the two groups of children at t1 differed to a larger extent in a quantitative rather than a qualitative sense, as larger discrep- ancies were observed between measures of breadth than depth. The lack of a significant group difference in depth of vocabulary knowledge represents a novel finding within the U.K. EAL liter- ature, and is further supported by the use of a bespoke rubric which indicated that both groups of children tended largely to produce the same types of knowledge in response to a request for verbal definitions of words. The following subsection will consider vocabulary growth over time, firstly in terms of vocabulary breadth and subsequently in terms of vocabulary depth.