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Evaluating the effectiveness of a phonologically
based reading intervention for struggling readerswith varying language profiles
Fiona J. Duff Marianna E. Hayiou-Thomas
Charles Hulme
Published online: 6 January 2011 Springer Science+Business Media B.V. 2011
Abstract This study evaluates Reading Interventiona 10-week supplementary
reading programme emphasising the link between phonological awareness and
readingwhen delivered in a realistic educational setting. Twenty-nine 6-year-olds
with reading difficulties participated in Reading Intervention and their progress and
attainments were compared with those of a representative control group from the
same classes, matched on age and gender. Language profiles were also explored.
Children with reading difficulties showed weaknesses in phonological awarenessand literacy as well as nonphonological oral language skills and nonverbal rea-
soning. During the intervention, the intervention group made significantly greater
progress than the control group in early word reading, phoneme awareness and
phonetic spelling. Over a 6-month follow-up period, the intervention group main-
tained its gains but during this time made significantly less progress on single word
reading, phoneme awareness and phonetic spelling than the control group. These
findings provide evidence that reading interventions can be delivered effectively in
standard educational settings. We argue that a better understanding of how to
manage withdrawal of intervention and how to address poor readers additional orallanguage weaknesses is needed.
Keywords Reading disability Intervention Phonology Oral language
Introduction
Extensive research has investigated the most effective methods for ameliorating
word-level reading difficulties. A general consensus is that approaches whichinvolve training phonological awareness and lettersound relationships, while
F. J. Duff (&) M. E. Hayiou-Thomas C. Hulme
Psychology Department, University of York, York YO10 5DD, UK
e-mail: [email protected]
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Read Writ (2012) 25:621640
DOI 10.1007/s11145-010-9291-6
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explicitly linking these skills to the task of reading, are effective for the majority of
children with reading difficulties (for reviews, see Bus & van IJzendoorn, 1999;
NICHD,2000; Torgerson, Brooks, & Hall, 2006; Torgesen, 2005).
Reading Intervention, as developed by Hatcher, Hulme, and Ellis (1994), is an
example of an evidence-based intervention that honours best practice. Its efficacyhas been demonstrated in a number of different studies, across various populations.
In the original study (Hatcher et al., 1994), Reading Intervention (incorporating
phonological awareness linked to reading) was delivered to children aged 7.5 years
who were experiencing reading difficulties. Children received 40 30-min sessions of
individual instruction over 20 weeks. While the Reading Intervention group made
greater progress than the control group on all measures of reading and spelling, the
progress of the other two treatment groups (reading alone and phonology alone) was
akin to that of the control group on all but one measure. The superiority in reading
for the Reading Intervention group was maintained at a 9-month follow-up.Hatcher et al. (1994) provided good evidence for the Reading Intervention
approach, making clear that explicit linkage between phonological awareness and
reading is important, and that training either skill in isolation is not particularly
effective. Findings from two subsequent meta-analyses (Bus & van IJzendoorn,
1999; NICHD, 2000) support this view given that the mean effect size of
phonological awareness training on reading is significantly increased when it is
combined with training in letter knowledge (ds = 0.18 or 0.38, respectively, for
phonological awareness in isolation; ds = 0.66 or 0.67, respectively, with letter
knowledge included).Further rigorous evidence for the effectiveness of Reading Intervention comes
from a randomised control trial (RCT) conducted by Hatcher et al. (2006b). In this
study, Reading Intervention was delivered to children aged 56 years, who
represented the bottom 8% of the population in terms of reading development.
Children were randomly assigned to either a 20-week intervention group or a
10-week (waiting list) intervention group. Reading Intervention was found to
produce improvements in reading, letter knowledge and phoneme awareness
(ds = 0.69, 0.94 and 0.46, respectively). An 11-month follow up showed that gains
in reading had been maintained.
Carefully controlled studies, like those above, are critical for demonstrating that
gains in reading can be attributed to a particular intervention programme. Such
tested programmes can then be passed confidently from researchers to practitioners.
However, it is important to check that the programme continues to produce
educationally significant results, to validate its feasibility and ongoing use. Here, we
report a novel approach to evaluating intervention, which takes the Reading
Intervention programme and assesses its effectiveness when it is initiated and
implemented not by researchers, but by schools as a routine part of their educational
practice.
The timing of this evaluation is also important, owing to significant shifts in
educational policy related to the teaching of literacy in the UK. The Independent
Review of the Teaching of Early Reading (Rose, 2006) recommends that for all
young children, The knowledge, skills, and understanding that constitute high
quality phonic work should be taught as the prime approach to learning to decode
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(to read) and encode (write/spell) print (p. 70). Therefore, the key principles of
teaching reading that underlie Reading Intervention (e.g. promoting phonological
awareness and phonic decoding) are more familiar elements of whole-class literacy
instruction than they were when Reading Intervention was first developed (Hatcher
et al., 1994), or last evaluated (Hatcher et al., 2006b). Thus, the major aim of thepresent study was to evaluate Reading Intervention, when co-ordinated by schools,
by assessing its efficacy against the evidence-based instructional background of
contemporary literacy education.
Evaluations of interventions usually consider children with diagnosed specific
reading problems. Here, we are interested instead in children that schools deem to
be in need of reading intervention. Preliminary research suggests that such children
might have weaknesses not only in phonological skills but also nonphonological
oral language skills including vocabulary and grammar (Duff et al., 2008). Thus, a
second aim of our work is to explore the linguistic profiles of children identified byschools as needing reading intervention.
To achieve our aims, children with weaknesses in reading participated in Reading
Intervention, and their literacy progress was compared to that of a representative
untreated control group drawn from the same classrooms. This comparison makes
for a conservative evaluation of Reading Intervention: The progress of children with
weaknesses in reading is being compared to that of children whose reading levels
are age-appropriate; and, in the wake of policy shifts, the baseline instructional
environment is one that includes many of the same key elements of the intervention.
Method
A 10-week reading intervention programme was implemented for a group of children
with weaknesses in word reading. Their progress during the intervention period was
compared to that of a representative group of untreated classmates. Children were
tested individually at school on several occasions, following informed parental
consent. A comprehensive test battery assessing literacy, language and cognitive
skills was administered to all children before the intervention began (t1, mean
age = 6;02). Immediately after the intervention finished, relevant literacy-based
skills were re-assessed (t2, mean age = 6;06). The post-test battery was repeated at a
6-month follow-up (t3,mean age =7;00).
Participants
Participants were drawn from eight primary schools in the UK county of North
Yorkshire that were running Reading Intervention in the second and third years of
formal schooling. Children in the intervention group were selected by professionals
within schools, and were identified as children with poor word reading skills who
would likely benefit from Reading Intervention. A representative peer-comparison
group served as the control group. This included children from the same classes
matched individually on gender and age to the intervention children. One
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intervention child was withdrawn part-way through the intervention programme due
to poor attendance. This resulted in a total of 30 participants in the control group
and 29 in the intervention group. Due to changing schools, only 26 children in the
intervention group were assessed at follow up. Further demographic information is
shown in Table1.
Assessment battery
Literacy
Letter-sound knowledge (t1, t2, t3)
Children were shown all 26 letters of the alphabet in a random but fixed order. They
were required to produce the associated sound of each letter.
Spelling (t1, t2, t3)
Children were asked to name pictures of 10 items and to write down each associated
word. A raw score was computed. Spellings were also scored according to how
closely the orthographic representations of the consonants matched the target
consonants: 4 points were awarded for each correct letter; 3 points for a letter that
differed from the target consonant by only one phonetic feature (place, manner or
voicing); 2 points for a partially represented digraph, or for a correct letter in the
wrong position; and 1 point for a letter more than one phonetic feature away from
the target consonant. Vowels were not scored to avoid any confounds owing to
regional variations in accents.
Single word reading (t1, t2, t3)
The BAS II Word Reading subtest (Elliot, Smith, & McCulloch, 1997) was
administered as a standardised test of single word reading. Children were also
administered a 43-item version of the Early Word Reading test (EWRSnowlinget al., 2009), which assessed childrens ability to read words that are frequently
encountered during the early stages of learning to read. A 50-item version of this
test was devised to avoid potential ceiling effects by adding seven more difficult
items from the BAS II Word Reading subtest.
Table 1 Demographics of the control and intervention groups, assessed pre-intervention
Group N Gender Mean age (SD) Range Diagnoses
(M:F) (years;months) (years;months) Dyslexia ADHD SLD
Control 30 15:15 6;02 (0;06) 5;037;03 0 0 3
Intervention 29 14:15 6;02 (0;07) 5;037;02 0 0 7
SLD speech/language difficulties, based on teacher report
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Phonological awareness
Phoneme awareness (t1, t2, t3)
Three subscales from theSound Linkage Test of Phonological Awareness (Hatcher,2000) provided a measure of ability to manipulate phonemes. Children were first
required to blend phonemes, for example upon hearing /t////p/, they were to
produce tap. Next, they were asked to segment phonemes, for example, break up
pet into its constituent phonemes /p/ /e/ /t/. Finally, the children were required to
delete phonemes from the beginning, middle, or end of a word, for example, /g/
from gone makes on.
Nonword repetition (t1)
The Childrens Test of Nonword Repetition (CNRepGathercole & Baddeley,
1996) was administered. Children were required to repeat 40 nonwords which
ranged in length from two to five syllables (e.g. glistow, versatrationist).
Rapid automatized naming (RAN) (t1)
To assess childrens rapid naming ability, the Naming Speed Test from the
Phonological Assessment Battery (PhABFrederickson, Frith, & Reason, 1997)
was administered. Children were first required to name the five relevant objects toensure that they had access to the requisite semantic labels. They were then
presented with a grid containing these five objects repeated at random to create a
series of 50 pictures. Their task was to name these objects in order as quickly as
possible. The task was repeated for a second grid containing the same items but
presented in a different order. Childrens performance was judged according to the
total time in which it took them to complete both trials.
Oral language
Receptive vocabulary (t1)
Comprehension of single words was measured using the British Picture Vocabulary
Scale II(BPVS IIDunn, Dunn, Whetton, & Burley,1997). For a variety of spoken
words, children were required to indicate which of four pictures most accurately
represented each target word.
Expressive vocabulary (t1)
Production of single words was assessed using a confrontation naming testthe
Assessment of Comprehension and Expression 6-11 (ACEAdams, Cooke,
Crutchley, Hesketh, & Reeves, 2001). Children were required to name a series of
pictures that represented a set of 25 nouns gradually increasing in level of difficulty.
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Expressive grammar (t1)
Two tests were administered to assess expressive grammar. In the Recalling
Sentences subtest of the Clinical Evaluation of Language Fundamentals III(CELF
IIISemel, Wiig, & Secord, 1995), children were asked to repeat back a series ofsentences, which increased in complexity and length. The Past Tense Probe from
theTest of Early Grammatical Impairment (TEGIRice & Wexler,2001) was also
administered. On each trial, a sentence relating to a picture was modelled in the
present continuous tense, and the child was then required to talk about the same
picture in the past tense.
Receptive grammar (t1)
The ability to understand grammar in spoken language was measured by theTest forReception of Grammar 2 (TROG 2Bishop, 2003). Upon hearing a sentence,
children had to point to one of four pictures that represented the grammatical
relations between the elements in the sentence (e.g. The elephant chases the duck).
Various grammatical constructions were tested.
Nonverbal ability (t1)
Nonverbal reasoning was assessed using the Pattern Constructionsubtest from theBAS II. Children were required to manipulate two-coloured squares and two-
coloured cubes to replicate abstract patterns which increased in complexity.
Successful replications were credited with points, with additional marks for faster
completion.
Behaviour (t1)
Each childs class teacher completed the Strength and Difficulties Questionnaire
(SDQGoodman, 1997) as a means of assessing childrens behavioural profiles.
Two outcomes are reported: total social deviance (a sum of scores from 4
subscaleshyperactivity, emotional symptoms, conduct problems and peer prob-
lems), and hyperactivity as an independent subscale. Lower scores reflect more
socially appropriate behaviour.
Inhibition (t1)
An estimate of childrens attention skills was provided by the Inhibitionsubscale ofthe Behaviour Rating Inventory of Executive Functioning (BRIEFGioia, Isquith,
Guy, & Kenworthy, 2000). Class teachers rated the extent to which a list of
behaviours typically indicating lack of inhibition (or presence of perseveration),
were evident in each child. Lower scores reflect better attention/inhibition.
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Teaching procedures
The intervention programme implemented in this study was Reading Intervention
(Hatcher et al.,1994,2004,2006a,b). Ten teaching assistants (TAs) were involved
in delivering the intervention, all of whom had received 4 days of training (from thelocal education authority), had previous experience of delivering the programme,
and whose instructional delivery had recently been observed in a quality assurance
exercise. The intervention is designed to run for 10 weeks, alternating between daily
group (n = 3) and individual sessions, lasting 20 min each. All sessions follow a
standard procedure, within which it is possible to tailor the level and focus of
teaching content to individual childrens needs.
Six of the children in the present evaluation received intervention of the
same content but always administered on an individual basisa pragmatic
decision made by the school. Analyses of variance showed that these childrendid not differ significantly from the remaining children in the intervention group
on pre-intervention word reading (Fs(1,27) =0.230.65, ps = .636.429, gp2s =
0.01). Nor did they differ in gains made on most outcome measures during the
intervention (Fs(1,27) = 0.003.62, ps = .979.068, gp2s = 0.000.12). This indi-
vidually tutored group made significantly less progress than the rest of the inter-
vention group on Early Word Reading (F(1,27) =9.91, p = .004, gp2
= 0.27).
Though this may appear contradictory, the NICHD (2000) report is not conclusive
on whether individual instruction is more effective than small-group instruction. In
terms of phonological awareness training, the effects on reading are significantlygreater when instruction occurs in small groups of 27 children (d =0.83)
compared with on a one-to-one basis (d = 0.45). However, there is no significant
difference concerning phonics instruction (small groups, d = 0.43; individually,
d = 0.57).
Group sessions
The group sessions begin with letter and word identification training (6 min)
letters and sight words are introduced and reinforced through multi-sensory
activities (e.g. writing on whiteboards, using tactile letters). The following 8 min are
occupied by phonological awareness activities. Predominately with reference to
Sound Linkage (Hatcher, 2000), children practise blending, segmenting, deleting
and transposing both syllables and (preferentially) phonemes. The link between
sounds and letters is also demonstrated, for example, through simple word-building
activities. Finally, the group narrate a sentence or short story together (e.g. by
describing a picture or event) and each child writes a section from it, in line with
their writing capabilities (6 min). Here, children are explicitly encouraged to deploy
their sound linkage (grapheme-phoneme correspondence) skills to aid spelling. The
TA scaffolds this activity according to each childs needs (e.g. the TA may spell
difficult words or allow children to practise writing a word on a whiteboard before
incorporating it in the final sentence/story).
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Individual sessions
The first activity in the individual sessions involves the child reading an easy book
(4 min)a book that can be read with above 94% accuracy. The childs ability to
read an instructional level book (9094% accuracy) is then formally assessed(5 min); TAs take a running record (miscue analysis) in which they detail reading
accuracy on a word-by-word basis, and categorise the nature of any errors made.
A further 2 min are allowed for making specific teaching points related to the childs
reading strategies (e.g. introducing new sight words, encouraging phrasing and
fluency). Finally, the child is introduced to a new book at the instructional level and
has a first attempt at reading this book alone, followed by a repeated reading with the
TA employing a scaffolding approach to shared reading (9 min). During all reading
activities, children are encouraged to use phonic decoding skills when they encounter
unknown words. For regular words, this might involve the child providing the soundfor every letter in a word and blending those sounds, all through the word, to read it
(Rose,2006). Other strategies, such as the use of contextual and visual cues, are also
taught.
Treatment fidelity
To monitor the fidelity with which the intervention was delivered, all TAs had one
teaching session observed. TAs were rated on the quality with which they delivered
key teaching components of the intervention (1 =
poor; 2 =
satisfactory; 3 =
good).The overall quality (across activities within individual and group sessions) was
deemed good, with an average rating of 2.71 (0.37) and a range of 13. Sessions were
also timed and on average lasted 19.09 (5.94) min (target = 20 min). As these TAs
were experienced in delivering Reading Intervention,and had recently undergone an
independent observation for quality assurance, this suggests that the intervention was
delivered with integrity.
Classroom instruction
Information was obtained from teachers regarding literacy instruction in the
classroom, in which children from both the control and intervention groups
participated. Questionnaires were returned from 6 out of 8 schools (representing 9
classrooms in total). In these schools, phonics was taught daily for around 15 min.
Throughout the week, children generally participated in guided reading as well as
independent or shared reading. More details are given in Table 2.
Results
Evaluation of intervention
The performance of both groups on various outcome measures at t1, t2 and t3 is
shown in Table 3together with Cohensdas a measure of the size of the difference
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between groups at each time of testing. We wished to assess the extent to which the
intervention group made greater progress between pre-test (t1) and the immediate
(t2) and delayed (t3) post-tests, compared to the representative untreated control
group. A series of one-way analyses of co-variance (ANCOVAs) was carried out for
this purpose. Short-term effects were assessed by testing for group differences on
raw scores of various outcome measures immediately after the intervention finished
(t2), controlling for corresponding t1 scores as the covariates. The results of theseanalyses for the intervention period are summarised by the grey bars in Fig.1,
which plots the relative gain in raw score (at the mean of the covariate) for the
intervention group over the control group. Any score greater than 0 represents
an advantage for the intervention group over the control group; where the
Table 2 Nature and frequency of reading instruction in the different classrooms
Classroom Phonics Guided reading Independent
reading
Shared
reading
Paired
reading
Reading cues
encouraged
1 15 mina day
20 min a day Twice aweek
Phonics, pictures,context, sight
word
recognition
2 20 min
a day
3 sessions in
small groups
every week
1 or 2
sessions
a week
Every day Occasionally
3 1520 min
a day
20 min 3 times
a week
Phonics, pictures,
context, sight
word
recognition
4 10 mina day
1520 minonce a week
10 mintwice
a week
Phonics, pictures,sight word
recognition
5 1015 min
a day
Once a week 1 or 2
sessions
a week
Range of methods
6 15 min
a day
30 min twice
a week
30 min
twice
a week
1520 min
3 times a
week
Phonics, pictures,
context
7 15 min
a day
15 min twice
a week
5 min once
a week
Every day 20 min a
week for
some
children
Phonics, pictures,
context, sight
word
recognition
8 15 min
a day
30 min twice
a week
Every day
9 Regularly 20 min
twice a
week
Guided readingan adult working with a small group of children, grouped by ability, to teach strategies
for reading with meaning; independent readingchild reading to himself, to encourage fluency and a
reading habit; paired readingone child reading with one adult or peer; shared readingan adult reading
with a group of children to model and scaffold fluent and expressive reading (with reference to PrimaryNational Strategy,2003)
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95% confidence interval does not cross the x-axis, this represents a statistically
significant effect.
Figure1 shows that the intervention group made significantly greater progress than
the control group on three main outcome measures: early word reading, phonetic
spelling and phoneme awareness. The intervention and control groups made similar
progress in letter knowledge, word reading and absolute spelling. In terms of
individual variation in response to intervention, only 5 out of 29 children in the
intervention group (17%) failed to increase their reading standard scores (where a gain
in standard score represents progress beyond the expected rate). One child dropped
5 standard score points, 1 child dropped 1 point, and 3 children remained stationary
(i.e. showed an expected rate of progress). While there was a general trend for these5 children to perform at a slightly lower level on most measures at t1, the only
significant difference was on phonetic spelling (F(1,25) = 5.84,p = .023, gp2
= 0.19).
The use of ANCOVA to evaluate the effects of intervention relies on the
assumption of equivalent regression slopes between groups. We assessed this in a
Table 3 Means (standard deviations) and effect sizes on outcome measures at pre-intervention (t1), post-
intervention (t2), and 6-month follow-up (t3) for the control and intervention groups
Measure Test point Max. Control Intervention Effect
size (d)
Letter knowledge t1 26 24.57 (3.19) 24.21 (2.06) 0.13
t2 25.13 (2.36) 25.38 (1.18) 0.13
t3 25.77 (0.82) 25.85 (0.46) 0.16
Early word reading t1 50 25.47 (14.54) 11.03 (8.70) 1.21***
t2 32.37 (14.98) 22.31 (12.12) 0.74**
t3 38.63 (12.29) 29.38 (11.81) 0.77**
Word reading, raw t1 90 20.43 (14.95) 8.10 (7.72) 1.04***
t2 29.67 (17.61) 16.17 (11.36) 0.91**
t3 39.40 (16.89) 22.19 (13.25) 1.13***
Word reading, standard t1 101.73 (15.29) 87.72 (9.73) 1.09***
t2 106.43 (15.77) 94.45 (9.71) 0.91**
t3 109.03 (13.73) 93.62 (10.77) 1.25***
Spelling, raw t1 10 2.90 (1.84) 1.03 (1.27) 1.18***
t2 4.17 (2.48) 2.52 (1.74) 0.77**
t3 5.33 (2.25) 3.31 (2.31) 0.89**
Phonetic spelling t1 92 76.70 (18.99) 60.41 (20.27) 0.83**
t2 81.17 (15.25) 76.86 (9.60) 0.34
t3 86.77 (6.50) 80.19 (10.06) 0.78**Phoneme awareness t1 18 10.50 (4.23) 5.97 (4.78) 1.00***
t2 11.17 (4.09) 9.83 (4.25) 0.32
t3 13.07 (2.85) 10.65 (4.24) 0.67*
N.B. Group differences tested with one-way analyses of variance: * significant at p\ .05; ** significant
at p\ .01; *** significant at p\ .001 At t1 and t2, control group N = 30, intervention group N = 29; at t3, control group N = 30, inter-
vention group N = 26
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series of regression models in which we entered the Covariate, Group (coded 0,1),
and the Group 9Covariate interaction term as predictors of outcome. In all cases,
except for phonetic spelling, the Group 9 Covariate interaction term was nonsig-
nificant (bs =
0.001.20, ts =
0.021.57, ps =
.121.983), which supports the useof an ANCOVA model with fixed slopes across groups. For phonetic spelling the
Group 9 Covariate interaction was significant indicating non-equivalent slopes
between groups [b = -0.34,t = -3.95,p\ .001; the slope relatingt2 scores tot1
scores was steeper in the control group (b = 0.90) than in the intervention group
(b = 0.80)]. In this model, however, there was a highly significant difference in
marginal means scores between the groups at the mean level of the covariate, of
4.58 points in favour of the intervention group (v2 = 6.37, p = .012). This
difference became progressively larger at lower levels of the covariate (initial
phonetic spelling score). The results of this analysis confirm that there is a reliable
effect of the intervention on phonetic spelling for children at the mean of the
covariate and below, but that the effects of the intervention reduce to nonsignificant
levels for children who start out with higher phonetic spelling scores.
Long-term effects of the intervention were evaluated in a similar way, this time
testing for group differences 6-months after the intervention finished (t3), with
corresponding t2 scores as the covariates. The results of these ANCOVAs for the
maintenance period are represented by the white bars on Fig. 1. Any score less than
0 represents a relative advantage for the control group, over the intervention group;
where the 95% confidence interval bars cross the x-axis, this represents a
statistically significant effect.The ANCOVAs show that after the intervention had ceased, the intervention
groups progress on tests of letter knowledge, early word reading and absolute
spelling did not differ from that of the control groups, and that its progress on
phoneme awareness, phonetic spelling and word reading was significantly slower.
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phon
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aren
ess
early
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wordreadin
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spellin
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phon
etic
spellin
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lette
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wareness
early
wordreadin
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wordreadin
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Relativeraws
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0.22
0.71
0.37
0.10
0.13
0.61
-0.13 -0.25
0.03
-0.29 -0.19 -0.17
Fig. 1 Relative advantage in raw scores (with 95% confidence intervals) on outcome variables for
the intervention group over the control group across the intervention period (in grey bars) and the
maintenance period (in white bars). Effect sizes (Cohens d) hover above the bars, calculated as the
difference between groups on raw gain scores divided by the pooled standard deviation of the covariate
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Analyses demonstrated that most variables met the assumption of homogeneity
of regression slopes (bs =0.082.00, ts =0.75 1.46, ps = .151.455)allowing
a fixed slopes, varying intercepts ANCOVA. The assumption was not met for
phonetic spelling [b = 0.44, t = 3.93, p\ .001; the slope relating t3 scores to t2
scores was steeper in the intervention group (b = 0.79) than in the control group(b =0.70)]. In a model including the Group 9 Covariate interaction, however,
there was a significant difference in marginal means scores between the groups at
the mean level of the covariate, of 4.04 points in favour of the control group
(v2 =7.26, p = .007). This difference became progressively larger at lower levels
of the covariate (phonetic spelling score at immediate post-test).These results show
that, for those whose post-test phonetic spelling scores fall at the mean of the
covariate and below, children in the control group are progressing more than those
in the intervention group on phonetic spelling during the maintenance period. This
difference in progress reduces to nonsignificant levels for children who have higherphonetic spelling scores at immediate post-test.
The measure of phoneme awareness also failed to meet the assumption of
homogeneity of regression slopes [b = 0.39, t = 2.13, p = .151; the slope relating
t3 scores to t2 scores was steeper in the intervention group (b = 0.87) than in the
control group (b = 0.85)]. As with phonetic spelling, in a model including the
Group 9 Covariate interaction there was a significant difference in marginal means
between the groups at the mean level of the covariate, of 1.42 points in favour of the
control group (v2 = 8.12,p = .004). This difference became progressively larger at
lower levels of the covariate (phoneme awareness at immediate post-test).Thus, forthose whose post-test phoneme awareness scores fall at the mean of the covariate
and below, children in the control group are progressing more than those in the
intervention group on phoneme awareness during the maintenance period. Again,
this difference in progress reduces to nonsignificant levels for children who have
higher phoneme awareness scores at immediate post-test.
In sum the intervention was shown to be effective. On three key literacy
measures (phoneme awareness, reading and spelling) the progress made during the
intervention period by a group of children selected as having poor reading skills was
greater than the progress made by a representative group of children who received
regular classroom teaching (including daily phonics training and reading practice
for most children). However, the rate of progress of the children in the intervention
group was not sustained once intervention was withdrawn. During this maintenance
period, their progress on letter knowledge, early word reading and spelling was not
different from that of the control groups but their progress on word reading,
phoneme awareness and phonetic spelling was significantly slower (at least, for the
latter two variables, for children performing at lower levels at the end of the
intervention).
Learner profiles
To obtain a better understanding of the characteristics of children selected to take
part in Reading Intervention, their abilities on a range of linguistic, cognitive and
behavioural measures were compared to those of the control group (see Table 3).
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As expected, the control group performed significantly better than the intervention
group on all measures of reading and spelling, with large effect sizes. The difference
in letter knowledge was not significant, though this reflects ceiling effects in both
groups. Performance on the remaining measures is shown in Table4. The
intervention group displayed significant deficits in phonological skills, as measured
by phoneme awareness and rapid object naming, though it did not differ
significantly from the control group on nonword repetition. The intervention group
performed significantly worse than the control group on all measures of grammar,
but both groups showed age-appropriate receptive vocabulary knowledge. Finally,
the two groups were equated in terms of their behavioural and attentional skills, but
the intervention group performed significantly worse than the control group on the
test of nonverbal reasoning.
Children were selected for Reading Intervention according to relative weaknessesin reading, based on teacher evaluations. Restricting profile analyses to children
who reach an objective definition of a reading deficit will give a more accurate
picture of the language profiles of such children. A reading deficit was quantified as
performance on the Early Word Reading test at least 1.25 SD below the control
Table 4 Comparing the means (and standard deviations) of the control (N = 30) and intervention
(N = 29) groups on a variety of cognitive, linguistic, and behavioural measures at t1
Measure Score Max. Control Intervention Effect
size (d)
Nonword repetition Raw 40 25.50 (5.93) 23.14 (7.43) 0.35
Standarda
105.03 (14.80) 98.93 (15.39) 0.41
Rapid naming Seconds 139.70 (32.62) 163.16 (33.04) 0.71**
Standardb 97.35 (14.16) 80.00 (14.97) 1.19**
Receptive vocabulary Raw 168 64.27 (13.28) 60.97 (14.77) 0.23
Standard 102.77 (11.97) 99.55 (12.24) 0.27
Picture naming Raw 25 8.87 (4.09) 6.72 (4.21) 0.52
Standardb
10.40 (2.48) 7.89 (2.89) 0.93**
Receptive grammar Raw 20 8.07 (3.61) 6.24 (3.18) 0.54*Standard 89.40 (15.59) 80.79 (13.48) 0.59*
Recalling sentences Raw 78 23.13 (9.24) 16.45 (9.92) 0.70*
Scaledb
8.55 (2.87) 5.61 (2.15) 1.16**
Past tense production Percentc 100 70.79 (12.10) 60.59 (17.19) 0.69*
Nonverbal reasoning Raw 59 26.60 (9.16) 20.76 (9.66) 0.62*
T-score 52.60 (9.50) 44.93 (10.02) 0.79**
Hyperactivity Raw 10 3.73 (2.88) 4.69 (2.98) 0.33
Total social deviance Raw 40 8.77 (6.55) 9.62 (5.44) 0.14
Inhibition Raw 30 14.47 (5.08) 14.86 (4.43) 0.08T-score 52.87 (9.68) 54.07 (11.54) 0.11
a Control group N = 30, intervention group N = 27; b Control group N = 20, intervention group
N = 18; c Control group N = 28, intervention group N = 27
* Significant at p\ .05; ** significant at p\ .01; *** Significant at p\ .001; p = .051
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group mean; this cut-off was chosen so that around 15% of children in the control
group were characterised with a reading deficitin line with normal distribution. In
all, 15 children met the inclusion criterion (4 control and 11 intervention children).
Deficits in aspects of oral language were defined in a similar way (at least 1.25 SD
below the control mean). Composite z-scores were created for vocabulary (recep-tive and expressive vocabulary) and grammar (receptive grammar and recalling
sentences). Phonology was represented by phoneme awareness skills. The measure
of nonverbal reasoning was used to define difficulties beyond language.
The prevalence of additional deficits in children with or without a reading deficit
is given in Table5. The frequencies suggest that language deficits are more
prevalent in children with reading deficit than those without. Indeed, chi-square tests
revealed that language and reading deficits are non-independent; classification of the
presence of a language deficit is contingent upon presence of a reading deficit. In
contrast, nonverbal deficits were independent of reading deficits; children were
equally likely to have a nonverbal deficit regardless of reading status.
The co-occurrence of reading and language deficits in individual children were
then considered. Forty-six percent of children with a reading deficit had an isolated
phonological deficit (compared with 7% of children without reading deficit).
However, deficits in phonology also patterned highly with deficits in nonphono-
logical oral language: 47% of children with a reading deficit had co-occurring
deficits in phonology and vocabulary or grammarusually both (compared with
9%). In contrast, isolated difficulties in nonphonological oral language skills in the
presence of intact phonological skills did not feature in children with a reading
deficit (compared with 11% of children without a reading deficit).
Summary of results
A 10-week reading intervention programme was delivered by trained TAs to 6-year-
old children who had been identified by their teachers as exhibiting relative
weaknesses in word reading. The progress of these children was assessed before and
after the intervention, and compared with a representative sample of age- and
gender-matched children from the same classrooms. The intervention group made
significantly greater gains over the course of the intervention than a representativecontrol group from the same classrooms on phoneme awareness, early word reading
and phonetic spelling. These gains were maintained over a 6-month no-intervention
maintenance period; though in general children in the intervention group were
progressing at a slower rate than those in the control group.
Table 5 Prevalence of
additional deficits in children
with or without a reading deficit
N.B. Critical values ofv2 with 1
df: 3.84,p = .05; 6.64, p = .01;
10.83, p = .001
No reading deficit
(N = 44)
Reading deficit
(N = 15)
v2 p
Phonology 7 (16%) 14 (93%) 29.84 .001
Vocabulary 6 (14%) 6 (40%) 4.80 .05Grammar 4 (9%) 6 (40%) 7.61 .01
Nonverbal 11 (25%) 5 (33%) 0.39 NS
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Comparisons of the two groups prior to the intervention indicated that children who
were identified by their teachers as needing Reading Intervention showed relative
weaknesses in literacy and phonology, as expected, but also wider difficulties in
nonphonological oral language (vocabulary and grammar) and nonverbal ability. This
pattern was confirmed in a profile analysis, which demonstrated that deficits in bothphonological and nonphonological aspects of oral language frequently co-occurred
with reading deficits.
Discussion
Previous research has demonstrated that the Reading Intervention programme
successfully improves the reading abilities of struggling readers. This study aimed
to build on this evidence base by conducting an educationally realistic evaluation ofReading Intervention, carried out in the wake of recent shifts in educational policy
relating to general reading instruction (e.g. Rose, 2006). The present study also
investigated the linguistic profiles of children selected by their teachers to
participate in Reading Intervention.
Twenty-nine 6-year-old children with reading difficulties who received Reading
Intervention underwent a comprehensive cognitivelinguistic assessment, and
performance on key phonological and literacy tasks was measured before and after
intervention. The progress of the intervention groups was compared with that of a
control group (children from the same classes, matched on age and gender). ReadingIntervention was again associated with improvement in key literacy skills. In
addition to expected deficits in phonology and literacy, some children with reading
difficulties demonstrated significant weaknesses in nonphonological oral language
(vocabulary and grammar).
Efficacy of reading intervention
The present evaluation of Reading Intervention adds to previous studies which
demonstrate its effectiveness in improving literacy skills of struggling readers (after
Hatcher et al., 1994, 2004, 2006a, b). Here, the intervention and control groups
made significant progress throughout the intervention period. After controlling for
differences in baseline performance, the groups made statistically equivalent gains
on a standardised test of word reading, letter knowledge and absolute accuracy of
spelling attempts. Crucially, the intervention group demonstrated significantly
greater progress than the control group in early word reading, phoneme awareness
and phonetic spelling (though for the latter variable, this effect was only significant
for children who started out with lower levels of phonetic spelling). It must be noted
that children in the intervention group remained significantly behind their peers in
single word reading and spelling skills.
A common metric for comparing intervention studies is the number of standard
score points in reading gained per hour of intervention (McGuiness, McGuiness, &
McGuiness,1996). A review of reading interventions which incorporate training in
phonemic awareness and phonemic decoding (akin to Reading Intervention) reports
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an average increase of 0.20 standard score points per hour (Torgesen et al., 2001).
The present implementation of Reading Intervention obtained an average gain of
0.59 standard score points per hour, which compares very favourably with previous
studies. Furthermore, only 5 of 29 children in the intervention group (17%) failed to
show an increase in reading standard score over the intervention period. Thisstatistic also compares well to other studies (e.g. Hatcher et al., 2006b).
The progress of all children was monitored 6 months after the intervention had
finished. In both groups, maintenance or even continued progress in literacy skills
was shown. Strikingly, while the intervention group either equalled or excelled the
control groups rate of progress during the intervention period, their rate of progress
lagged behind that of the control group during the maintenance period. Though
confirming the effectiveness of Reading Intervention, this implies that some poor
readers may need support for longer than 10 weeks. Future research might pursue
the hypothesis that children who are gradually phased out of Reading Interventionafter 10 weeks will demonstrate better maintenance of treatment gains than those
who experience an immediate cessation.
When drawing conclusions from this study, it must be borne in mind that there was
a lack of random assignment of children to groups, and that groups were not matched
on literacy skills at the outset. While we acknowledge that an RCT would have been
preferable, we nonetheless argue that the results are still meaningful. On the basis of
previous RCTs (e.g. Hatcher et al., 2006b), we have good reason to suppose a priori
that Reading Intervention is causal in producing gains in literacy. Furthermore, the
very design of this study is conservative. Children were selected by their teachers toreceive intervention on the basis that they had weaknesses in reading relative to their
peers; that is, they had been showing slower progressachieving a lower level of
literacy compared to their peers, despite the same length of instruction. It is therefore a
reasonable assumption that the intervention groups progress would have continued to
be relatively slower, had the intervention not been effective. Yet our results show that
these poor readers made more progress than a representative group of children who
themselves were making at least average progress in reading. Finally, the relatively
slower pace of progress of the intervention group in the no-intervention follow-up
period confirms this treatment effect.
Learner profiles
A second aim of this study was to assess the linguistic profiles of children with
reading difficulties. Children selected to receive Reading Intervention tended to
display weaknesses in expressive and receptive grammar and expressive vocabu-
lary, in addition to their expected weaknesses in phonological skills.
The children given intervention in this study were selected by their teachers as
having reading difficulties, relative to their class peers. Consequently, the degree of
reading difficulty varied across schools, and not all children included in the
intervention group would have difficulties enough to qualify as reading disabled
according to typical diagnostic criteria. This observation is in line with other
research which shows that while teachers are good at identifying the children at-risk
of dyslexia (good sensitivity), they tend to over-estimate the number of children
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who are truly at-risk (poorer specificity; Snowling, Duff, Petrou, Schiffeldrin, &
Bailey, in revision).
To gain a more accurate understanding of the co-occurrence of reading and
language difficulties, the whole sample was re-categorised according to the presence
or absence of a reading deficit, as defined relative to the average readingperformance of the control group. Language (but not non-verbal) deficits were
significantly more likely to occur in children with a reading deficit, compared to
those without. A large majority of children with reading deficits had a phonological
deficit (93%). Interestingly, the occurrence of this phonological deficit was split
across two sub-types of reading disability: 46% of those with reading deficits had a
concomitant deficit in phonological aspects of oral language alone; another 47% had
co-occurring deficits in both phonological and nonphonological aspects of oral
language. Such profiles approximate both classic dyslexia and its broader
phenotype, respectively (Scarborough, 1990; Snowling, Gallagher, & Frith, 2003;Snowling, Muter, & Carroll,2007). These results mirror the findings of Catts, Fey,
Zhang, and Tomblin (1999), who tracked the development of a large sample of
children, categorising them as either good or poor readers in their third year of
schooling, and retrospectively considered their language skills at school entry. Both
studies support the conclusion that weaknesses in nonphonological oral language
feature among a significant proportion of children identified primarily for their
reading difficulties.
It is important to consider why broader oral language difficulties are observed in
children who present primarily with a reading deficit. The most prominent theory ofdyslexia (and by extrapolation, reading disorders) asserts that the main cause is a
core deficit in phonological processing (Stanovich, 1988; Vellutino, Fletcher,
Snowling, & Scanlon, 2004). At first blush, this explanation would not anticipate
concomitant deficits in broader oral language skills; nonetheless, some attempt may
be made at reconciling these broader language deficits within this theoretical view.
In terms of vocabulary skills, the children selected for Reading Intervention
exhibited average receptive skills, with a tendency for weaknesses in expressive
skills. It is hypothesised that expressive vocabulary is more closely related to word
reading, as task performance necessitates access to fully specified phonological and
semantic representations (Chiappe, Chiappe, & Gottardo, 2004; Wise, Sevcik,
Morris, Lovett, & Wolf, 2007). Children with dyslexia are known to struggle with
word finding and confrontational naming and these problems are commonly assumed
to stem from phonological weaknesses, either in the encoding or accessing of
phonological representations (Nation, Marshall, & Snowling, 2001; Snowling, van
Wagtendonk, & Stafford, 1988; Swan & Goswami, 1997; see Messer & Dockrell,
2006 for discussion). The current study also found poor morphological skills in
children participating in Reading Intervention; it has been argued elsewhere that
morphological impairments may be caused by a phonological deficit (Bird et al.,
2003; Chiat,2001; Joanisse & Seidenberg,1999).
Thus, the observation of expressive vocabulary and morphological deficits in
children with reading difficulties is not necessarily incompatible with the
phonological deficit hypothesis. Notwithstanding this, it is less clear how the
observed deficit in receptive syntax could be accounted for by weaknesses in
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phonological processing. The precise nature and direction of the relationship
between the various subdomains of oral language (phonology, morphosyntax and
semantics) requires further study, and this will have implications for theories of
reading development and disorders. However, the critical point for present purposes
is that these subdomains of oral language are likely to interact. Coupling this withthe knowledge that reading disorders are characterised by a primary deficit in
phonological processing (Vellutino et al., 2004), it becomes unsurprising that
nonphonological oral language difficulties are observed in children with reading
disability.
Clearly, future longitudinal studies need to assess the nature of the relationships
between intra-domain (phonological and nonphonological oral language) and inter-
domain (oral and written language) deficits in children at risk of reading difficulties.
Summary and conclusions
This study adds to earlier evaluations of Reading Intervention and shows that when
delivered in an educationally realistic way, it is associated with improvements in
fundamental literacy skills. The findings support growing evidence that deficits in
both phonological and nonphonological aspects of oral language co-occur with
reading difficulties. Such data are in line with the thesis put forward by Snowling
(2008) that a phonological deficit is the main cause of reading difficulties, but that
this risk factor may be moderated by weaknesses in broader (nonphonological) orallanguage weaknesses. The finding that weaknesses in nonphonological areas of
language typify a significant proportion of children with reading difficulties suggests
that future intervention programmes ought to address both phonological and
nonphonological aspects of oral language as foundations for literacy development.
Acknowledgments The present study was funded by the Biotechnology and Biological Sciences
Research Council. Grateful thanks are extended to Maggie Snowling for her input, to North Yorkshire
Children and Young Peoples Services for support of this work (particularly Simon Gibbs and Glynnis
Smith), and to all of the pupils, teaching assistants and schools who participated.
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