1. hobbies and interests
2. reading

Does a Visual-Orthographic Deficit Contribute
to Reading Disability?
Nathlie A. Badian
Harvard Medical School and Children's Hospital
Boston, Massachusetts
In this study, visual-orthographic skills were defined as the ability to
recognize whether letters and numerals are correctly oriented. Aims
were to investigate whether visual-orthographic skills would contribute independent variance to reading, and whether children with a
visual-orthographic deficit would be more impaired readers than similar children without this deficit. Participants were 207 children, aged
8 to 10 years, who attended school in a small suburban community.
Because of the evidence that phonological awareness and naming speed
are strongly related to reading, visual-orthographic skills were entered
into hierarchical regression analyses following these variables.
With age, verbal IQ, and verbal short-term memory also controlled,
visual-orthographic skills accounted for significant independent
variance in all reading measures. When children with a visualorthographic deficit (29% of the sample) were compared with those
without this deficit, they were significantly lower on all reading variables. At 8 to 10 years of age, reading progress of some children continues to be hampered by a problem in orthographic memor¢ for the
orientation of letters and numerals. Such children will require special
attention, but their problems may be overlooked. As recommended by
Willows and Terepocki (1993), there is need for further research on the
phenomenon of letter reversals when they occur among children beyond first grade.
Annals of Dyslexia, Vol. 55, No.l, 2005
Copyright 02005 by The International Dyslexia Association ®
ISSN 0736-9387
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VISUAL-ORTHOGRAPHIC DEFICIT AND READING DISABILITY
29
Key Words: Letter orientation, low level visual processing,
naming speed, phonological awareness, reading
disability, visual-orthographic skills
For the past 20 years or more, the impetus in dyslexia research
has been to prove that the underlying cause of reading difficulties is poor phonological awareness (Brady & Shankweiler,
1991; Rack & Olson, 1993; Torgesen, Wagner, & Rashotte, 1994;
Wagner & Torgesen, 1987). Serial naming speed was included
under the rubric of phonological awareness by Wagner and
Torgesen (1987). Evidence has been mounting, however, that
naming speed contributes variance to reading independently of
phonological awareness (Badian, 1993a; Barker, Torgesen, &
Wagner, 1992; Manis, Doi, & Bhadha, 2000; Olson, Forsberg, &
Wise, 1994). Numerous studies have shown that naming speed
is significantly correlated with reading and differentiates between normal and disabled readers (Cornwall, 1992; McBrideChang & Manis, 1996; Meyer, Wood, Hart, & Felton, 1998; Wolf,
1991, 1997). The conviction that, in addition to phonological
awareness, naming speed is an important facilitator of reading
skills, led to the double-deficit hypothesis (Wolf & Bowers,
1999, 2000). According to this hypothesis, some poor readers
have a single phonological or naming speed deficit, and some
have both deficits (the "double deficit " group). The double
deficit group is the most impaired in reading skills.
THE ROLE OF THE V I S U A L S Y S T E M I N D Y S L E X I A
The visual system, as well as the auditory, is involved in learning to read (Chase, 1996; Ehri & Wilce, 1985), and it is difficult
to determine which system is more critical for reading development (Chase, 1996). In spite of the venerable history of visual
deficits in dyslexia that goes back to Hinshelwood (1895) and
Pringle Morgan (1896), interest in this aspect of dyslexia research has been minimal in recent years. Neglect of the contributions of the visual system to reading intensified following the
publication of Vellutino's (1979) authoritative book on dyslexia,
which made a strong case for linguistic deficits as the cause of
dyslexia and stressed the lack of evidence for visual deficits.
These conclusions have been criticized (Fletcher & Satz, 1979;
Willows, Kruk, & Corcos, 1993). Stanovich (1992) cites several
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studies that found differences between disabled and nondisabled readers in visual experiments using nonverbal stimuli,
brief presentations, and psychophysical procedures. He points
out that much of the evidence contradicting the idea of visual
deficits in reading disability comes from studies employing arrays exposed for several seconds or more.
Visual deficits potentially associated with reading disability
range from poor performance on low level visual processing
tasks to difficulties with complex visual-orthographic measures. In their causal model for visually based reading impairments, low level visual processing leads either to the visual
(object) processor or to the visual (orthographic) processor
(Seymour & Evans, 1993). The route from the visual (orthographic) processor then leads to central reading processes. The
following brief review will examine studies of the relationship
of low level visual tasks to reading, visual-orthographic (surface) subtypes of dyslexia, and letter recognition and orientation problems in dyslexia.
L O W LEVEL V I S U A L P R O C E S S I N G A N D R E A D I N G
In a number of recent experiments, low level visual tasks such
as visual motion, contrast sensitivity, visual tracking, and temporal processing have been shown to correlate with reading,
and, at least in some studies, to differentiate between groups of
good and poor readers (Boden & Brodeur, 1999; Booth, Perfetti,
MacWhinney, & Hunt, 2000; Cornelissen & Hansen, 1998; Eden,
Stein, Wood, & Wood, 1995; Iles, Walsh, & Richardson, 2000;
Olson & Datta, 2002; Stein, Talcott, & Witton, 2001; Talcott et al.,
2002).
Eden and her colleagues (1995) concluded that their findings contradict the view that visual problems are not associated
with reading disability. In their study, reading disabled children
were significantly poorer than age-matched normal readers on
some visual and eye movement tasks, as well as on verbal and
phonological measures. One of the more comprehensive recent
studies reported that in a random sample of 350 children (mean
age 9 years), both visual coherent movement and auditory frequency discrimination predicted a significant proportion of the
variance in the reading of exception words and nonwords, as
well as in orthographic and phonological processing, after accounting for differences in age and nonverbal IQ (Talcott et al.,
2002).
The relationship of low level visual tasks to orthographic
processing has also been stressed by Stein, Talcott, and Witton
VISUAL--ORTHOGRAPHIC DEFICIT AND READING DISABILITY
31
(2001), who found that motion sensitivity strongly correlated
with orthographic skills and spelling, and continued to account
for unique variance after controlling for phonological skill.
Deficits in rapid visual processing (moving dot detection) were
significantly associated with orthographic processing in children with reading disability, but not in reading disabled adults
(Booth et al., 2000). These findings were explained by the differential developmental model in which orthographic processing deficits are a delay condition that should diminish by
adulthood.
V I S U A L - O R T H O G R A P H I C SUBTYPES OF DYSLEXIA
Early subtyping studies of reading disability repeatedly found a
subtype with a deficit in some aspect of visual processing (for a
review, see Watson & Willows, 1993). More recently, some
researchers have looked for differences in children with developmental dyslexia to parallel the surface and phonological subtypes reported in acquired dyslexia (Bailey, Manis, Pedersen, &
Seidenberg, 2004; Curtin, Manis, & Seidenberg, 2001; Gustafson,
2001; Manis, Seidenberg, Doi, McBride-Chang, & Pedersen,
1996; Manis et al., 1999; Manis, Szeszulski, Holt, & Graves, 1990;
Stanovich, Siegel, & Gottardo, 1997). Phonological dyslexics
have poor phonemic awareness and difficulty reading nonwords, whereas surface dyslexics tend to rely on phonological
recoding when reading because of weak orthographic imagery,
and to have difficulty reading exception words. In their studies,
Manis and his colleagues have compared the dyslexic subgroups with younger reading level (R-L) matched children as
well as with age-matched controls. When phonological and surface dyslexia was defined by the performance of the R-L group,
the phonological group was twice as large (34%) as the orthographic (surface) group (17%) (Manis et aL, 1990). In a one-year
follow-up, the surface group was found to be not very stable
(Manis et al., 1999).
General conclusions are that surface dyslexia represents a
delay or developmental lag in acquiring literacy skills (Curtin,
Manis, & Seidenberg, 2001; Gustafson, 2001; Stanovich, Siegel,
& Gottardo, 1997). Stanovich and his colleagues (1997) found
strong evidence for both surface and phonological dyslexic subtypes when dyslexic children were compared with age-matched
controls (17 phonological, 15 surface), but when they were
compared with R-L controls, the surface subgroup virtually
disappeared (17 phonological, 1 surface). It was concluded that,
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in contrast to the developmental lag of the surface dyslexic subgroup, phonological dyslexia seems to reflect true developmental deviance. In a S w e d i s h study, there was a less dramatic
decrease in surface dyslexics w h e n the R-L comparison was
made (Gustafson, 2001).
LETTER R E C O G N I T I O N A N D O R I E N T A T I O N PROBLEMS
IN DYSLEXIA
In the earliest stages of exposure to print, visual (surface)
dyslexics have great difficulty recognizing numbers and letters,
and even after they can read quite well, they still have a serious
problem recalling how words look (Willows & Terepocki, 1993).
It is necessary to draw on stored orthographic images for reading of irregular words. Insufficient a t t e n t i o n to i n d i v i d u a l
letters would seem to lead to inaccurate orthographic representations (Foorman, 1994). Even for skilled readers, visual processing of individual letters in words is important (Adams &
Bruck, 1993). Further, if orthographic imagery for single letters
is unstable, establishing automatic orthographic-phonological
connections will be impeded. Detailed visual information, including the orientation of letters, influences the whole process
of phonological and semantic decoding (Lachmann, 2002).
In t h e i r r e v i e w s , W i l l o w s a n d T e r e p o c k i (1993) a n d
Terepocki, Kruk, and Willows (2002) document evidence (now
neglected) for the tendency of many dyslexic children to make
letter orientation errors w h e n reading and writing. It is worth
noting that studies of letter orientation errors e x a m i n e d by
Terepocki and her colleagues (2002), excluding those involving
r e a d i n g w o r d s or n o n w o r d s , w i t h o n e e x c e p t i o n (Wolff &
Melngailis, 1996), are d a t e d no later t h a n 1985. Wolff and
Melngailis (1996) found that dyslexic children aged 7 to 10 years
m a d e significantly more reversal errors than normal readers
from the same families w h e n the task was repeated naming of
confusable letters, but there was no difference between groups
of older children and adults. As this was a naming task, it is difficult to determine whether the errors were due to naming or
visual deficits.
In their own research, Terepocki, Kruk, and Willows (2002)
compared 10-year-old average readers and children with reading disability. The children with reading disability m a d e more
orientation errors than average readers on computer-based reversal detection tasks (numbers, letters, letter strings, words),
and more reversal errors on controlled writing tasks. The two
VISUAL-ORTHOGRAPHIC DEFICIT AND READING DISABILITY
33
groups did not differ on attention control tasks, however. The
authors suggest that the reading disabled group's difficulties in
discriminating similar looking items could be due to poorly
specified representations of letters. They concluded that although reversal errors are likely to disappear in children with
reading disability as their reading and writing skills improve,
the consequences of early letter orientation errors need further
study.
Willows and Terepocki and their colleagues (e.g., Terepocki,
Kruk, & Willows, 2002; Willows & Terepocki, 1993) have probably studied the phenomenon of letter reversals more than any
other researchers in recent years. Their aim has been mainly to
document the incidence and nature of letter orientation errors
in reading disability, and they have not included tests of other
reading-related skills such as phonological awareness and naming speed. Hence, there is a dearth of information as to how letter orientation errors are related to other cognitive skills. There
has also been very little research devoted to the connection between low level visual processes and letter orientation confusions.
Recently, however, Stein and his research team have demonstrated a link between poor visual motion sensitivity, purported
to be due to magnocellular dysfunction, and the tendency to
misidentify and transpose letters w h e n attempting to read
(Stein, 2001a, 2001b). The sensitivity with which children can
fixate with their eyes correlates well with the sensitivity of their
magnocellular systems to visual motion. Children with binocular instability are tess able to stabilize their eyes during fixation,
and hence the eyes' lines of sight may cross and letters can appear to do so also. That is why dyslexics tend to reverse the
order of letter features, thus confusing d with b and p with q,
and to transpose the order of letters within words (Stein, 2001a,
2001b). There may, therefore, be a link between poor visual motion sensitivity and the tendency to misidentify, transpose, and
reverse letters.
R A T I O N A L E FOR T H I S S T U D Y
There is convincing evidence that phonological awareness and
naming speed play pivotal roles in reading development, but
there is evidence that visual and visual-orthographic tasks of
many types also contribute to reading. A visual task that warrants further investigation (Willows & Terepocki, 1993) is the
phenomenon of letter reversal errors, but there has been minimal interest in the topic in the more than 10 years since Willows
and Terepocki pointed out the need for investigation.
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For the current study, we looked for a visual task involving
recognition of letter orientation errors that w o u l d not be conf o u n d e d with w o r d recognition or spelling, nor require letter
n a m i n g . T h e test s e l e c t e d r e q u i r e s the c h i l d to r e c o g n i z e
whether isolated u p p e r case letters and numerals are correctly
oriented, and measures m e m o r y for the correct visual form of
letters and numerals (Jordan, 1980). It can be classified as a measure of basic visual-orthographic skills, and will be referred to,
in generic terms, as a "visual-orthographic" task or as measuring " v i s u a l - o r t h o g r a p h i c " skills. A later v e r s i o n of the test
(Jordan, 1990), which includes lower case letters, was not used
in this study because children are often confused w h e n faced
w i t h reversible (and phonologically similar) letters such as b
and d. Terepocki and her colleagues (2002) differentiate between
reversible letters (i.e., those forming another letter w h e n reversed such as b and d) and nonreversible letters (i.e., those not
forming another letter w h e n reversed such as B and D).
A n u m b e r of studies have included the Jordan (1980) test
(Badian, 1993a, 1993b, 1994, 1996, 1997). This task predicted
reading progress in 6- to 8-year-old children followed up after
two years (Badian, 1993b). Poor readers m a d e significantly
more errors than adequate readers, even controlling for differences in IQ a n d r e a d i n g e x p e r i e n c e (Badian, 1993a). W h e n
garden-variety and dyslexic poor r e a d e r s - - m a t c h e d in age and
w o r d r e a d i n g - - w e r e compared, the dyslexic group m a d e significantly more errors, suggesting that the poorer performance of
the d y s l e x i c g r o u p w a s n o t d u e to less e x p o s u r e to p r i n t
(Badian, 1994, 1996, 1997). The Jordan (1990) test was given to
an unselected cohort of 131 first grade children in November.
The test correlated significantly (r = -.44, p .0000) with a traditional orthographic choice test given about three months later,
and also w i t h visual and v i s u a l - m o t o r tests given to most of
this cohort as preschoolers nearly two years earlier (visual letter
and w o r d m a t c h i n g r = -.44, p .0000; n a m e w r i t i n g r = -.40,
p .0000). Correlations of the Jordan with preschool letter and
shape naming were lower (letter naming r = -.24; shape naming
r = -.09) (author's unpublished data).
In order to determine as precisely as possible the contribution to reading of the letter and n u m b e r orientation test, constructs k n o w n to play important roles in reading development
(e.g., p h o n o l o g i c a l a w a r e n e s s , n a m i n g speed) w e r e also included in this study. A p h o n e m e deletion measure was chosen
to r e p r e s e n t p h o n o l o g i c a l a w a r e n e s s (see B o w e r s & Ishaik,
2003) and rapid n a m i n g of letters to represent n a m i n g speed.
VISUAL-ORTHOGRAPHIC DEFICIT AND READING DISABILITY
35
These two types of tasks, along with s o u n d b l e n d i n g a n d digit
n a m i n g s p e e d , h a v e f r e q u e n t l y b e e n u s e d as m e a s u r e s of
phonological awareness a n d n a m i n g speed w i t h s o m e success
(e.g., Manis, Doi, & Bhadha, 2000).
The two questions this s t u d y s o u g h t to a n s w e r were:
1. Will visual recognition of l e t t e r / n u m e r a l reversals contribute i n d e p e n d e n t variance to reading, after accounting for the contributions of phonological awareness a n d
n a m i n g speed?
2. Are children w i t h a deficit in the visual recognition of
l e t t e r / n u m e r a l reversals m o r e i m p a i r e d r e a d e r s t h a n
those w i t h o u t this deficit?
METHOD
PARTICIPANTS
The participants were 207 children aged 8 to 10 years referred
for an evaluation or a routine follow-up re-evaluation in a small
s u b u r b a n school district over three to four years. Reasons for referral included learning difficulties in reading, m a t h , or written
language; ADHD; or m i l d behavioral problems. There were 136
boys a n d 71 girls. M e a n age w a s 8.8 years (SD = 0.6) a n d m e a n
grade p l a c e m e n t was 3.1 (SD = 0.5). All b u t two children were
in Grades 2 or 3. Only children with a full scale IQ of at least 80,
b u t not m o r e t h a n 130, were i n c l u d e d as participants. All spoke
E n g l i s h as their p r i m a r y l a n g u a g e . E t h n i c i t y w a s C a u c a s i a n
93.7%, A f r i c a n - A m e r i c a n 3.4%, a n d Hispanic 2.9%. M o s t parents were skilled or semiskilled workers, or h a d m i n o r w h i t e
collar jobs.
MEASURES
The following m e a s u r e s were i n c l u d e d in the evaluation of the
participants.
Phonological Awareness. The child was asked to delete a
syllable or a p h o n e m e from a w o r d in v a r y i n g positions (e.g.,
b e d r o o m w i t h o u t bed, pat w i t h o u t / p / ) (Rosner, 1979). There
w e r e t w o practice items (syllable deletion) f o l l o w e d by three
syllable a n d 10 p h o n e m e deletion test items. All items were administered to all children. O n local n o r m s based o n 166 children
aged 6 to 10 years, the m e a n score at age 8 to 10 years w a s 10.6
(SD = 2.25). Scores are reported as the n u m b e r correct o u t of a
possible 13. Split-half reliability coefficients in an earlier local
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BADXaN
s a m p l e of 131 c h i l d r e n in G r a d e s 1-3 h e t e r o g e n e o u s classes
w e r e .92 (ages 7-8) a n d .89 (ages 8-10).
Naming Speed. The child n a m e s as fast as possible five
l o w e r case letters (oaspd) r e p e a t e d 10 times in r a n d o m o r d e r
a n d d i s p l a y e d o n a c h a r t in a 5 x 10 f o r m a t ( R A N Letters:
D e n c k l a & Rudel, 1974). U s i n g the D e n c k l a a n d R u d e l n o r m s
m e a n scores, r e p o r t e d as the time t a k e n in seconds to complete
the chart, are as follows: age 8, 31 seconds (SD = 7), age 9, 25
seconds (SD = 5), a n d age 10, 24 seconds (SD -- 2). H o w e v e r , in
a v e r y r e c e n t r e n o r m i n g (Wolf & Denckla, 2005), m e a n scores
differ f r o m the original: age 8, 35 seconds (SD = 14), a n d ages
9-10, 31 seconds (SD = 10). Thus, a child classified as h a v i n g a
n a m i n g s p e e d deficit on the early n o r m s w o u l d not necessarily
receive this classification on the recent norms. Test-retest reliab i l i t y w a s .87 f o r 85 c h i l d r e n a g e d 5 to 10 y e a r s (Wolf &
Denckla, 2005). Bowers a n d Ishaik (2003) report test-retest reliability a b o v e .90 for their research s a m p l e s of children in grades
2 t h r o u g h 5, a n d stability o v e r o n e - a n d t w o - y e a r p e r i o d s of
a b o v e .85.
Visual-Orthographic Skills. The child is given a page on
w h i c h there are 27 u p p e r case letters in three r o w s of nine, a n d
14 n u m e r a l s in t w o r o w s of seven (Jordan, 1980, Level 1), and is
a s k e d to look carefully along the r o w s a n d to cross out a n y letters or n u m b e r s that are "back to front" or " b a c k w a r d . " Eleven
of the 27 letters (P,S,L,R,C,B,E,Z,G,F,K) a n d five of the 14 n u m e r als (3,7,9,4,5) are p r e s e n t e d as left-right reversals or m i r r o r images. Using Jordan's norms, an error score one or more
s t a n d a r d deviations greater t h a n e x p e c t e d classified a child as
h a v i n g a v i s u a l - o r t h o g r a p h i c deficit. A n error score m o r e than
one s t a n d a r d d e v i a t i o n greater t h a n expected for age is _ 4 at
age 8, _> 3 at age 9, a n d _> 2 at age 10. Scores r e p o r t e d are the
n u m b e r of errors. Test-retest reliability based on the n o r m a t i v e
p o p u l a t i o n was .87 at ages 8 a n d 9 (Jordan, 1980).
Intellectual Ability. The WISC-R or WISC-III (Wechsler,
1974, 1991) was a d m i n i s t e r e d to each child to obtain m e a s u r e s
of v e r b a l a n d n o n v e r b a l cognitive ability. S t a n d a r d scores for
age are reported.
Verbal Short-term Memory. The WISC-R or WISC-III Digit
S p a n s u b t e s t w a s i n c l u d e d as a m e a s u r e of s h o r t - t e r m verbal
m e m o r y . O n Digits F o r w a r d , the child repeats strings of n u m bers just as heard. O n Digits Backward, the strings m u s t be rep e a t e d in reverse sequence. There are t w o trials for each string
of the s a m e length. Both sections of the test are d i s c o n t i n u e d
after failure o n b o t h trials. Scaled scores b a s e d o n age, calcu-
VISUAL--ORTHOGRAPHIC DEFICIT AND READING DISABILITY
37
lated from the total n u m b e r of strings (Forward and Backward)
repeated correctly, are reported.
Reading Measures. Three types of reading tests were used.
Reading of single w o r d s was tested by the Woodcock Reading
Mastery Test-Revised (WRMT-R) (Woodcock, 1987). N o n w o r d
r e a d i n g w a s t e s t e d by the WRMT-R W o r d A t t a c k subtest.
Reading Comprehension was tested by the Passage
C o m p r e h e n s i o n subtest of the WRMT-R or by the R e a d i n g
C o m p r e h e n s i o n subtest of the Wechsler Individual Achievement
Test (WIAT) (Psychological Corporation, 1992). The WRMT-R
Passage Comprehension uses a cloze procedure whereas on the
WIAT R e a d i n g C o m p r e h e n s i o n subtest, the child reads sentences or passages and then answers oral questions asked by
the examiner. Six children were not given reading comprehension tests because o f lack of time. All reading measures are reported as standard scores based on age.
PROCEDURES
Each participant was tested individually in a quiet room in his
or her school, generally in three one-hour sessions, with breaks
if needed. An educational psychologist administered the WISC,
and the measures of phonological awareness, n a m i n g speed,
and visual-orthographic skills. The reading tests were administered either by the educational psychologist or by a special education teacher.
GROUP FORMATION
Participants w e r e d i v i d e d into two groups, based on performance on the visual-orthographic measure of l e t t e r / n u m e r a l s
reversals detection, using the deficit criteria already described:
(1) v i s u a l - o r t h o g r a p h i c d e f i c i t (VO) g r o u p , a n d (2) n o
v i s u a l - o r t h o g r a p h i c deficit (NVO) group. Groups w e r e compared on reading measures, on variables associated with reading, and on intellectual ability.
RESULTS
Means, s t a n d a r d deviations, a n d ranges for all variables are
given in table I for the total sample. There was no overall gend e r d i f f e r e n c e on a M A N O V A t h a t i n c l u d e d all v a r i a b l e s :
F(1,196) = 1.55, p .116, and, therefore, gender was not a factor in
any analysis.
The three IQ means were close to the normative population
mean of 100, but mean reading standard scores were seven to nine
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Table I. Descriptive Data for the Total Sample ( n = 207).
Variable
M
SD
Age
8.8
0.6
Verbal IQ
99.0
11.7
74-140
Performance IQ
99.9
12.2
74-133
Full Scale IQ
99.3
11.0
81-127
9.5
2.4
1-13
2.3
2.2
0-11
36.3
9.0
19-74
Phoneme Deletion
Vis-Orth.(errors)
R A N Letters (secs.)
Digit Span*
Word Reading**
Range
8.0-10.4
8.8
2.6
2-17
90.6
t2.3
46-128
N o n w o r d Reading**
92.0
12.7
42-132
Reading Compreh. **
91.4
11.5
43-117
Note: Vis-Orth = visual-orthographic.
* Scaled scores; ** Standard scores.
points lower. Mean phonological awareness, visual-orthographic,
and verbal short-term m e m o r y scores were below the normative means, t h o u g h not significantly. The m e a n time taken for
n a m i n g speed (RAN Letters: 36.3 seconds) was more than one
standard deviation greater than expected for age 9 years on the
Denckla and Rudel (1974) norms, but not on the recent norms
(Wolf & Denckla, 2005). Although the age range was fairly restricted, there was a wide range in scores for most of the variables, including those standardized by age, probably reflecting
the heterogeneity of the referred sample.
T h e r e w a s a possible ceiling effect on the p h o n o l o g i c a l
a w a r e n e s s task ( p h o n e m e deletion). On the 13-item test, approximately one-fourth of the sample (n = 53, 25.6%) obtained
scores of 12 or 13, which was more than one standard deviation
above the sample mean. On the other hand, a substantial proportion of the participants f o u n d the task difficult with 21.3%
(n -- 44) scoring m o r e than one s t a n d a r d deviation below the
mean.
As the visual-orthographic measure was the m a r k e r task, it
should be noted that there was considerable variation in error
scores on this task, with a range from 0 to 11 and a standard deviation approximately as large as the m e a n score. The same percentage of children (22.2%) scored approximately one standard
deviation above and below the m e a n error score. Ten children
(4.8%) m a d e seven or more errors (more than 2 standard devia-
VISUAL-ORTHOGRAPHIC DEFICIT AND READING DISABILITY
39
tions above the mean).These children tended to be slightly younger
(M = 8.6 years) than the sample m e a n and were exceptionally
poor readers (Word Reading: M = 74.8, SD = 9.8). Verbal IQ was
also two points lower than the sample mean. These 10 children
also had deficits in naming speed a n d / o r phonological awareness.
It is possible that inattention m a y contribute to lower scores
on the visual-orthographic task. Unfortunately, no measure of
attention w a s i n c l u d e d in the study. As a r o u g h indication,
however, the 35 children whose primary referral was for ADHD,
or for w h o m A D H D was a major contributing factor, w e r e compared with the rest of the sample on the v i s u a l - o r t h o g r a p h i c
measure. Mean error scores did not differ: A D H D group, M =
2.29 (SD = 1.8), n o n - A D H D group, M = 2.28 (SD = 2.3) (F[1,205]
= 0.00, p .987).The two g r o u p s also d i d not differ in n a m i n g
speed, which could be affected by inattention.
CORRELATIONS AMONG VARIABLES
Intercorrelations a m o n g the variables are s h o w n in table II. As
the sample size was more than 200, correlations as low as .14
were significant but not meaningful. The negative correlations
of naming speed and visual-orthographic skills with other variables reflect the fact that higher scores indicate lower performance. Although reading scores were standardized by age, age
was negatively related to w o r d reading and r e a d i n g comprehension. Thus, there was a tendency for older children to have
lower age-based standard scores, which suggests that they had
a more severe reading disability than younger children.
Phonological a w a r e n e s s a n d n a m i n g s p e e d w e r e significantly correlated with all IQ and reading measures, and phonological a w a r e n e s s also c o r r e l a t e d s i g n i f i c a n t l y w i t h v e r b a l
short-term memory. In a d d i t i o n to its significant correlations
with reading, visual-orthographic skills correlated significantly
with naming speed and phonological awareness, but not with
verbal short-term m e m o r y or the IQ measures.
Phonological awareness had the highest correlation of any
nonreading variable with a reading measure (nonword reading:
r = .62). As n o n w o r d reading requires phonological decoding,
the strength of this correlation suggests that the p h o n e m e deletion test administered, a l t h o u g h including only 13 items, is a
reasonably sensitive measure of phonemic awareness.
HIERARCHICAL REGRESSION ANALYSES
Hierarchical regression analyses were performed to determine
the u n i q u e variance c o n t r i b u t e d to r e a d i n g m e a s u r e s by the
NonW
RdCom
10.
11.
-.17
-.13
-.22
-.05
-.11
-.23
.02
.11
-.06
-.12
1
.40
.23
.32
.04
.36
-.14
.27
.85
.40
2
.24
.11
.14
-.08
.18
-.15
.17
.82
3
.38
.20
.28
-.02
.33
-.17
.27
4
.47
.62
.46
-.24
.38
-.17
5
-.33
-.26
-.39
.18
-.12
6
.40
.33
.36
-.12
.79
.80
-.36
-.38
-.37
.65
10
r .14 - .17 p = .05; r .18 to .22 p = .01; r = .23 p = .001.
Note: V I Q = V e r b a l IQ, PIQ = P e r f o r m a n c e IQ, FSIQ = Full Scale IQ, Ph.Del. = P h o n e m e Deletion, R A N L = R A N Letters, Digit
Sp = Digit S p a n , V i s - O r t h = v i s u a l - o r t h o g r a p h i c , W o r d R d = W o r d r e a d i n g , N o n W = N o n w o r d r e a d i n g , R d C o m =
Reading Comprehension.
Vis-Orth
WordRd
DigitSp
7.
9.
RANL
6.
8.
FSIQ
PhDel
PIQ
3.
5.
VIQ
2.
4.
Age
1.
Variable
Table II. Intercorrelations A m o n g Variables.
7~
VISUAL-ORTHOGRAPHIC DEFICIT AND READING DISABILITY
41
visual-orthographic measure. Age, verbal IQ, and verbal shortterm memory were entered first, second, and third into each
analysis, to control for the effects of these variables on reading
performance.
In order to define as precisely as possible the unique contributions of the visual-orthographic measure to reading, phonological awareness and naming speed were also entered into
the regression analyses. In the first analysis, the v i s u a l orthographic measure was entered sixth, following phonological awareness and naming speed. In the next two analyses,
phonological awareness and naming speed were each entered
sixth, in order to compare their contributions with that of the
visual-orthographic task.
Age, verbal IQ, and verbal short-term memory (Digit Span)
together accounted for 19% of the variance in word reading,
24% in reading comprehension, and 12% in nonword reading.
When entered last (i.e., in sixth order of entry), the visualorthographic task accounted for significant independent variance in each reading measure, and for more variance in reading
comprehension than phonological awareness or naming speed.
In sixth order of entry, both phonological awareness and naming speed also accounted for significant independent variance
in each reading measure, with phonological awareness accounting for more variance in nonword reading. The hierarchical regression analyses are shown in table III.
BETWEEN-GROUP ANALYSES
There were 60 children (29%) with a visual-orthographic deficit
and 147 with no visual-orthographic (NVO) deficit. The performance of the VO and NVO groups on the study variables was
compared using ANOVA with the alpha level set at .05.
The groups differed in age (VO group older) and in phonological awareness (VO group lower), in addition to the groupdefining measure, but did not differ in IQ, naming speed, or
verbal short-term memory. The VO group was significantly
lower on all reading variables. When ANCOVA was performed
on the reading variables, with age and phonological awareness
as covariates, the VO group was still significantly lower: word
reading, F(1,203) = 16.65, p .0000; reading comprehension,
F(1,196) = 13.74, p .0003; n o n w o r d reading, F(1,203) = 10.42,
p .0012. Group means and ANOVA results are shown in table
IV. Effect sizes for reading were .77 word reading; .69 nonword
reading; .74 reading comprehension.
.12
.19
.30
.42
.48
.34
.43
.48
.32
.38
.48
3. Dspan
4. PhonD
5. RANL
6. VisM)rth
4. RANL
5. VisMgrth
6. PhonD
4. Vis-Orth
5. PhonD
6. RANL
.10
.06
.13
.05
.09
.15
.06
.12
.11
.07
.07
.05
6.5***
5.5***
-6.6***
4.8***
-5.7***
-6.6***
-4.8***
-6.5***
5.5***
4.0***
4.2***
-3.1"*
.49
.44
.39
.49
.45
.33
.49
.41
.34
.24
.17
.03
.05
.05
.15
.04
.12
.09
.08
.07
.10
.07
.14
.03
-4.1"**
4.2***
-6.9***
.4.1"**
-6.4***
-5.0***
-5.6***
-4.7***
5.3***
4.4***
5.8***
-2.3*
.01
.47
.45
.24
.47
.27
.17
.47
.43
.40
.12
.05
.01
.02
.21
.12
.20
.10
.05
.04
.03
.28
.07
.04
*p= .05. **p=.01, ***p = .001.
Note: Dspan = Digit Span, PhonD = Phoneme Deletion, RANL = R A N Letters, Vis-Orth = visual-orthographic.
.05
1. Age
2. VerbIQ
Variable
-2.6**
8.7***
-5.6***
8.7***
-5.2***
-3.4***
-4.0***
-3.2***
9.6***
4.0**
2.8**
-1.7
Table III. Hierarchial Regression Analyses: Contributions of Variables to Reading Measures.
Word Reading
Reading Comprehension
Nonword Reading
R2
R 2 Change
t
R2
R 2 Change
t
R2
R 2 Change
t
VISUAL-ORTHOGRAPHICDEFICITAND READINGDISABILITY
43
T a b l e IV. C o m p a r i s o n o f V O a n d N V O G r o u p s o n A l l V a r i a b l e s .
Variable
VO Group
n = 60
M
SD
NVO Group
n = 147
M
SD
F(1,205)
P
Age (yrs.)
8.9
0.6
8.8
0.5
3.9
.049
Verbal IQ
100.5
12.1
98.4
11.6
1.3
.255
Performance IQ
99.5
12.8
100.1
12.0
0.1
.778
Full Scale IQ
99.8
11.7
99.0
10.8
0.2
.617
Phoneme
Deletion
8.8
2.4
9.8
2.4
7.3
.007
RAN Letters
(secs)
36.7
10.2
36.2
8.7
0.1
.716
Digit Span
8.2
2.3
9.0
2.7
3.4
.066
Visual-Orth.
(errors)
4.9
2.1
1.2
1.2
269.1
.000
Word Reading
83.8
11.7
93.3
11.4
29.4
.000
Nonword
Reading
85.8
12.0
94.5
12.2
22.2
.000
Reading
Comprehens
85.4
12.8
93.9
9.9
25.2
.000
Note: VO Group = visual-orthographic Deficit Group; NVO Group = No
visual-orthographic Deficit Group; RAN = Rapid Automatized
Naming. Standard scores are given for reading.
T h e n u m b e r o f p o o r r e a d e r s ( s t a n d a r d s c o r e =85) in t h e t w o
g r o u p s w a s a l s o e x a m i n e d . C h i s q u a r e t e s t s w e r e c a r r i e d o u t to
compare the groups. Results were:
Word reading
Reading
comprehension
V O g r o u p : n = 37 (61.7%); N V O
n = 32 (21.8%).
C h i s q u a r e (df 1) = 30.53, p =.001
VO
n
Chi
Nonword reading VO
n
Chi
g r o u p : n = 30 (50.8%), N V O
= 27 (19.0%)
s q u a r e (df 1) = 20.80, p = .001
g r o u p : n = 28 (46.7%), N V O
= 36 (24.5%)
s q u a r e (df 1) = 9.80, p = .005
group:
group:
group:
The VO group was approximately one standard deviation
b e l o w t h e n o r m a t i v e m e a n o n e a c h r e a d i n g m e a s u r e a n d 8 t o 10
points below the NVO group. There were also significantly
more poor readers in the VO group. The VO group's lower
score on the phonological awareness measure strongly suggests
44
BADIAN
that their p o o r r e a d i n g c o u l d be d u e , at least in part, to a
phonological awareness deficit. However, the group continued
to be significantly lower than the NVO group on all reading
measures w h e n the difference in phonological awareness was
statistically controlled.
DISCUSSION
This s t u d y investigated w h e t h e r the ability to distinguish between correctly and incorrectly oriented u p p e r case letters and
n u m e r a l s w o u l d contribute i n d e p e n d e n t variance to reading
after controlling for the contributions of reading-related constructs (phonological awareness, naming speed). It also investig a t e d w h e t h e r c h i l d r e n w i t h a d e f i c i t on the o r i e n t a t i o n
measure (Jordan, 1980) w o u l d be more impaired readers than
similar children without this deficit.
The letter and numeral orientation measure is referred to in
this study as a "visual--orthographic" task, and children who were
low on the task are described as having a "visual-orthographic"
deficit. The stimuli of the orientation task are undeniably visual
and it is doubtful that n a m i n g the stimuli w o u l d improve accuracy of response. The measure is referred to as orthographic on
the grounds that letters and numerals are the basic raw materials of the orthography. As defined by Wagner and Barker (1994,
p. 245), "Orthographic processing refers to making use of orthographic information w h e n processing written or oral language.
An orthography refers to the system of marks that make up a
printed language." These authors add that, in English, the orthography includes u p p e r and lower case letters, numerals, and
punctuation marks.
D O E S ABILITY TO D E T E C T LETTER A N D N U M E R A L
ORIENTATION ERRORS CONTRIBUTE INDEPENDENT
VARIANCE TO READING?
Hierarchical regression analyses were carried out to answer the
question w h e t h e r the visual-orthographic measure (detection
of letter and numeral orientation errors) w o u l d contribute indep e n d e n t variance to reading after accounting for the contributions of phonological awareness and n a m i n g speed. Age, verbal
IQ, and verbal short-term m e m o r y w e r e entered first into each
analysis to control for the effects of these variables on reading.
It was found that, after controlling for the contributions of
the three variables listed above, the visual-orthographic mea-
VISUAL-ORTHOGRAPHIC DEFICIT AND READING DISABILITY
45
sure accounted for significant independent variance in each
reading measure, and for more variance in reading comprehension than phonological awareness or naming speed (table III). It
is hypothesized that the higher contribution to reading comprehension is due to the greater demands for efficient and automatic visual-orthographic processing w h e n the stimuli are
sequences of words rather than single words. There is little time
for slow phonological decoding, if meaning is to be obtained,
and children who have difficulty differentiating single letters
accurately are likely to make errors differentiating between orthographically similar words in the text. In the hierarchical regression analyses, phonological awareness contributed far more
to nonword reading than visual-orthographic skills or naming
speed (table III). Naming speed, however, accounted for more
variance in word reading than phonological awareness or
visual-orthographic skills.
Some studies have compared the amount of variance contributed to reading by typical orthographic and phonological
measures (e.g., Barker, Torgesen, & Wagner, 1992; Cunningham,
Perry, & Stanovich, 2001), but there is minimal evidence for the
contributions of letter orientation measures.
In a study of 170 children, aged 6 to 10 years, recognition of
letter/numeral reversals (Jordan, 1980) accounted for significant independent variance in word reading and reading comprehension after controlling for the contributions of IQ, reading
experience, p h o n o l o g i c a l a w a r e n e s s , a n d n a m i n g s p e e d
(Badian, 1993a). Following age, IQ, and two phonological tests
entered together (phonological choice, phoneme deletion), ort h o g r a p h i c processing ( o r t h o g r a p h i c choice, h o m o p h o n e
choice) accounted for significant independent variance in five
reading measures administered to 89 third grade children
(Barker, Torgesen, & Wagner, 1992). The proportion of unique
variance contributed to word identification by orthographic
processing was 7%. Thus, the independent contribution of typical orthographic measures to word identification was comparable to the independent contribution of the visual-orthographic
measure of the current study, which also controlled for the effects of verbal short-term memory and letter naming speed.
It can be concluded that visual-orthographic skills, defined
as the ability to recognize the correct orientation of upper case
letters and numerals, contribute independent variance to reading, even after controlling for the contributions of phonological
awareness and n a m i n g speed. A l t h o u g h the phonological
awareness measure (phoneme deletion) in the current study
46
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was short, its relatively high correlation w i t h n o n w o r d reading
suggests that it is a reasonably valid m e a s u r e of phonological
awareness. In a s t u d y in w h i c h the difficulty leveI of phonological m e a s u r e s w a s c o m p a r e d , p h o n e m e elision (i.e., p h o n e m e
deletion) a n d b l e n d i n g tasks a p p e a r e d to be the m o s t discriminating tasks in the battery (Schatschneider, Francis, Foorman,
Fletcher, & Mehta,1999). It is possible, however, that if a longer
a n d m o r e r i g o r o u s m e a s u r e of p h o n o l o g i c a l a w a r e n e s s h a d
been used, the variance contributed by visual-orthographic
skills to reading m i g h t have been less.
ARE C H I L D R E N WITH A DEFICIT IN R E C O G N I T I O N OF
LETTER/NUMERAL REVERSALS MORE IMPAIRED READERS
THAN THOSE WITHOUT SUCH A DEFICIT?
The second question this s t u d y investigated was w h e t h e r children with a v i s u a l - o r t h o g r a p h i c deficit are m o r e i m p a i r e d readers t h a n t h o s e w i t h o u t s u c h a deficit. Sixty (29%) of the 207
children in the s a m p l e h a d a v i s u a l - o r t h o g r a p h i c deficit, defined as an error score one standard deviation above the m e a n
on the l e t t e r / n u m e r a l reversal r e c o g n i t i o n test. G r o u p s with
a n d w i t h o u t a v i s u a l - o r t h o g r a p h i c deficit did not differ in IQ,
v e r b a l s h o r t - t e r m m e m o r y , or letter n a m i n g s p e e d , b u t the
v i s u a l - o r t h o g r a p h i c g r o u p was significantly lower in phonological a w a r e n e s s , as w e l l as on all r e a d i n g m e a s u r e s . W h e n
phonological awareness a n d age were controlled, the VO group
c o n t i n u e d to be significantly lower on the r e a d i n g measures.
The finding that 8- to 10-year-old children w h o have difficulty
recognizing w h e t h e r u p p e r case letters a n d n u m e r a l s are correctly oriented are poorer readers than those w i t h o u t this difficulty is consistent with the results of the Terepocki, Kruk, and
Willows (2002) study. That s t u d y directly c o m p a r e d groups of
10-year-old average a n d p o o r readers. W h e n asked to press a
key if they s a w an item (letters, numerals, letter strings, words)
on the c o m p u t e r screen that "looked backwards," p o o r readers
m a d e significantly m o r e errors. The two g r o u p s did not differ in
attention or s p e e d of m o t o r processing. In the c u r r e n t study,
there also d i d not a p p e a r to be an attention effect, as children
for w h o m A D H D was a major concern obtained an almost identical m e a n score on the v i s u a l - o r t h o g r a p h i c task as children for
w h o m A D H D was not a concern.
R e a d i n g experience d o e s n o t a p p e a r to play a significant
role in r e a d i n g g r o u p differences on the v i s u a l - o r t h o g r a p h i c
measure. In several studies, 8- to 9-year-old garden-variety poor
readers were significantly superior on this m e a s u r e to dyslexic
VISUAL-ORTHOGRAPHIC DEFICIT AND READING DISABILITY
47
children with whom they were matched in age and word recognition (Badian, 1994, 1996, 1997). However, the dyslexic group
did not differ from y o u n g e r r e a d i n g level (R-L) controls
(Badian, 1996, 1997), a finding that could be interpreted as an
indication of a developmental lag. The current study probably
included both dyslexic and garden-variety poor readers, but the
primary aim of the study was not the comparison of different
groups of readers.
Willows and Terepocki (1993) quote a s t u d y (Cairns &
Steward, 1970) that found that 4- to 6-year-old children could orient upper case letters in space with relative accuracy and suggested that orientation difficulties beyond 6 years of age would
predict reading disability. A developmental route has been observed from preschool ability to match letters and words visually,
to early first grade recognition of letter and numeral orientation
errors, to later first grade orthographic processing (orthographic
choice), which continued to predict reading and spelling at least
through Grade 7 (author, unpublished data).
A variety of factors may be involved in the ability to recognize whether alphanumeric symbols are correctly oriented, but
what appears to be necessary for success on the orientation
measure used in this study is memory for the stored visual representation of alphanumeric symbols. Lachmann (2002) proposes that reversals occur i n memory, and not in perception,
due to deterioration of the integration of phonological and visual information in working memory. A child who has been unable to store images of symbols that are accurate in orientation,
or who has difficulty revisualizing stored orthographic information (whether letters, numerals, or words), is likely to perform poorly on a reversal recognition task. This difficulty in
storing a n d / o r recalling orthographic representations will be
associated particularly with problems in reading of exception
words as phonological decoding skills may circumvent word
recognition problems if the words to be read are phonologically
regular. Children who have word recognition problems due to
difficulties in storing a n d / o r retrieving orthographic representations, and who make letter orientation errors, are probably
those referred to by Willows and Terepocki (1993) as "visual
dyslexics" and may also be included in groups of surface
dyslexics (e.g., Manis et al., 1996). Jackson and Coltheart (2001)
differentiate between visual and surface dyslexia with visual
dyslexia referring specifically to cases in which there are confusions of similar appearing letters, and left-right reversals and
letter-order errors.
48
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The importance of visual pattern recognition is acknowledged by Bowers and Ishaik (2003) in their insightful discussion
of the contributions of rapid automatized naming to the understanding of reading disability. Their review of research leads
them to ask whether it is a sluggish visual system that acts as a
bottleneck to the integration required for successful RAN performance. They stress that visual naming speed reflects the
rapid integration of lexical access and retrieval processes with
lower level visual, auditory, and motoric (articulation) processes. What RAN, or naming speed, and the letter/numeral
orientation test of the current study have in common is the need
for accurate visual pattern recognition. The correlation between
RAN letters and the l e t t e r / n u m e r a l orientation test in this
study was significant, but low (.18), reflecting the fact that they
have a visual recognition element in common, but RAN letters
involves other processes.
Although m a n y children's poor performance on a letter
naming speed test may be determined by one or more of the
higher processes discussed by Bowers and Ishaik (2003), the
present study suggests that some poor readers' difficulty in recognizing letters is determined not by slow name recall, but, at
an earlier stage, by problems in visual-orthographic memory
for letter patterns. The orientation of individual letters is a
major factor in letter pattern recognition. A child who has problems with recognition of the correct orientation of letters is
likely to be a slow and inaccurate reader of both words and
nonwords due to a problem in acquiring accurate and stable orthographic representations of words.
CONCLUSIONS
In summary, this study found that, even with stringent controls
for other variables associated with reading, recognition of
letter/numeral orientation errors made unique contributions to
reading. The study also found that children with a deficit in
recognition of l e t t e r / n u m e r a l orientation errors were poorer
readers than those without a deficit. It must be stressed, however, that the results are based on a school referred sample,
which may not be representative of the general child population. The ethnic makeup of the sample (94% white) may also
differ from that found in many communities.
In spite of the significant roles of phonological awareness
and naming speed in reading development, these two variables
VISUAL-ORTHOGRAPHIC DEFICIT AND READING DISABILITY
49
leave a considerable proportion of the variance in reading unexplained, which leads to the logical hypothesis that other, unspecified, variables are contributing additional variance to
reading. Basic visual-orthographic skills such as the accurate
recognition of letter orientation may be among those variables.
There is no doubt that higher level orthographic skills (e.g.,
Olson, Forsberg, & Wise, 1994) account for significant variance
in reading.
This study indicates that there are some children whose
reading development continues to be hampered by a problem
in orthographic memory for the orientation of letters (and numerals) long after most children have easily mastered this task.
The problems of such children require special attention, but
may be overlooked, especially if, as is frequently the case, they
also have n a m i n g s p e e d a n d / o r p h o n o l o g i c a l a w a r e n e s s
deficits. As r e c o m m e n d e d many years ago by Willows and
Terepocki (1993), more research on the phenomenon of letter reversals is needed, especially when it occurs in children beyond
first grade.
Address correspondence to: Nathlie Badian, 101 Monroe Road,
Quincy, MA 02169. Tel.: 617-496-5881; fax: 617-471-0986; e-mail:
[email protected]
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Manuscript received September 23, 2004.
Final version accepted March 8, 2005.