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Copyright ? 2006-2013 Scientific Research Publishing Inc. All rights reserved.
2011. Vol.2, No.7, 737-742
Copyright © 2011 SciRes. DOI:10.4236/psych.2011.27113
Do Deaf Children Delay in Their Executive Functioning Due to
Their Delayed Language Abilities?
Rafet Firat Sipal, Pinar Bayhan
Department of Child Development, Hacettepe University, Ankara, Turkey.
Received July 1st, 2011; revised August 6th, 2011; accepted September 16th, 2011.
Language use during daily interactions plays a key role in executive functioning. Given that increasingly sophis-
ticated language is required for effective executive functioning as an individual matures, it is likely that children
with delayed language skills will have difficulties in performing tasks which are related to executive functioning.
The aim of this study was to investigate the relationship between language ability and executive functioning in a
group of deaf students who communicate using spoken Turkish, as measured by their performance on WSCT
(Wisconsin Card Sorting Test). For that purpose, 82 children who are deaf were tested by means of their lan-
guage skills and executive functioning abilities. Results show that, language skills have significant impact on the
executive functioning of the children. Gender was found to be another factor affecting the executive functions.
Results were discussed with the relevant literature.
Keywords: Hearing Impairment, Children Who Are Deaf, Executive Functions, Language Development
Spoken language development in severely or profoundly deaf
children is generally delayed compared with their hearing peers
(Baker-Hawkins & Easterbrooks, 1994). Regarding to their
delay in typical development, children who are deaf experience
difficulties when communicating with their families, hearing
peers, and the wider society (Meadow-Orlans & Erting, 2000;
Hindley, 2000). As language is the main component of social
communication, it also has key importance for cognitive proc-
essing of individuals.
The key component of how an individual processes social
and cognitive input learning to solve problems and to behave
intelligently is through the use of language (Ylvisaker & De
Bonis, 2000). Language provides individuals with the capacity
to think, learn, and behave through understanding and interact-
ing through shared symbols. The process of recognition, coding,
storing, and recalling of any social or cognitive information
create links necessary for future processing. Language enables
the storing and recalling of information that is already known
and reasoning about what an individual does or does not know.
While using language in that way, individuals are in fact com-
municating with themselves about how to solve a problem and
to learn (Barkley, 1997). From this point of view, how language
skills are developed and used appropriately is a complex proc-
ess requiring the correct functioning of many different cogni-
tive processes. These processes, or executive functions, enable
effortful and flexible organization of information and the in-
corporation of strategic and goal-orientated behavior (Borkowski
& Muthukrishna, 1992). Simply, such executive functions en-
able intelligent thought, problem solving, and learning to take
The construct of executive function (EF) encompasses the or-
ganizational and self-regulatory skills required for goal-directed,
non-automatic behavior. It has been variously described as
including planning, initiating, monitoring, and flexibly correct-
ing actions according to feedback; sustaining and shifting atten-
tion; controlling impulses and inhibiting pre-potent but mal-
adaptive responses; selecting goals and performing actions that
may not lead to an immediate reward, with a view to reaching a
longer term objective; holding information in mind whilst per-
forming a task (working memory); and creatively reacting to
novel situations with non-habitual responses (Hughes & Gra-
ham, 2002; Shallice & Burgess, 1991; Welsh & Pennington,
1988). Recent theoretical conceptualizations of EF suggest that
it is not a unitary function, but encompasses a range of dissoci-
able skills, such that it is possible for an individual to fail on
some executive tasks whilst succeeding on others (Baddeley,
1998; Garavan, Ross, Murphy, Roche, & Stein, 2002; Miyake
et al., 2000). Different EF skills may follow independent de-
velopmental pathways, some of which may be more strongly
associated with language (and thus more affected by the con-
sequences of deafness) than others.
Language deficits in deaf children, which typically reflect
delayed rather than disordered functioning, are potentially use-
ful in clarifying the relationship between language and EF be-
cause these children’s difficulties are secondary to a peripheral
cause. Electroencephalogram evidence (Wolff, Kammerer,
Gradner, & Thatcher, 1989; Wolff & Thatcher, 1990) has
shown differences in the neural organization of the bilateral
frontal cortex (closely linked to EF abilities) and the left tem-
porofrontal area (involved in expressive language) of deaf and
hearing children. A weaker development of these cortical areas
might be reflected in both poorer language and poorer EF in
deaf children. No studies have examined EF comprehensively
in deaf children, although a number have included tests that
assess some EF components as part of wider investigations.
There is some evidence for impaired attention in deaf children
compared to their hearing peers (Khan, Edwards, & Langdon,
2005; Mitchell & Quittner, 1996). Planning and problem solv-
ing have also been found to be poorer in deaf children when
compared with hearing children (Das & Ojile, 1995; Marschark
& Everhart, 1999). Further, there are numerous studies report-
ing on the intelligence and problem-solving abilities of deaf
children, but there are relatively few that are specific to higher
level cognitive processing and particularly to EF. In fact, since
R. F. SIPAL ET AL.
1994, only three studies have reported specifically on the EF
abilities of school-aged deaf children (Luckner & McNeill,
1994; Marschark & Everhart, 1999; Surowiecki et al., 2002).
Two of these studies have assessed EF using different versions
of Tower tests (Luckner & McNeill, 1994; Surowiecki et al.,
2002), whereas one has used 20 Questions (Marschark &
The development of language and that of EF is considered to
closely linked. Given the wealth of research examining the
impact of deafness on the language acquisition of deaf children,
it is surprising that limited research has been carried out deaf
children’s EF, and that there are such few studies explicitly
examining the relationship between language skills and EF in
deaf children. Many of the existing studies have examined deaf
children’s performance on only a few of the EF subcomponents.
Therefore, the aim of this study was to investigate the relation-
ship between language ability and executive functioning in a
group of deaf students who communicated using spoken Turk-
ish, as measured by their performance on a standardized test of
executive function: WCST. It was hypothesized that, language
ability would relate to performance on the measures of execu-
tive functioning. For that purpose, we tested 82 children who
are deaf in order to assess their EF and language abilities. We
did not include a comparison sample in our study because it is
already well documented in literature that normally developing
children have better executive functioning than their hearing
impaired counterparts. Thus, we compared hearing impaired
children according to their language abilities and we grouped
children into two groups as; with and without preschool special
education experience. The rationale for this grouping is the well
documented positive effect of early special education on the
language skills of children who are deaf. As it is previously
reported children with language impairments present lower EF
compared to children with typical language development,
comparing children who are deaf with different language abili-
ties will provide precious/vital/ novel information on the rela-
tionship between language skills and EF of children who are
The present study was conducted in the metropolitan area of
Ankara, the capital city of Turkey. All segregated schools for
the deaf in Ankara were contacted for participation. The pur-
pose of the study was explained and discussed with the Princi-
pals of these schools. However, one of the schools refused to
participate in the study due to the busy schedule. In total 82
children between 10 - 14 ages were recruited into the study. Of
these participants 42 children were boys and 40 were girls with
a mean age of 11.91 (s = 1.44) All the children had bilateral,
sensory-neural (S/N), severe hearing loss (71 - 95 dB) as they
were all attending classes in segregated schools for the deaf. 39
of the children (47.6%) had early special education history
whereas 43 of them (52.4%) not. Children with a secondary
disability were excluded from this study.
Demographic information form: A demographic information
form was used to gather information about the family, child,
child’s education and child’s communicative behaviors.
Peabody Picture Vocabulary Test (PPVT): PPVT as devel-
oped by Dunn in 1959 (as cited in American Guidance Services,
AGS, 2005) was utilized to assess the vocabulary knowledge of
children as well as their receptive language. The PPVT is an
individual language performance test, orally administered in
less than 20 minutes. No reading is required by the subject, and
scoring is rapid and objective. Item responses are made by
pointing or multiple choice selections, dependent upon the sub-
ject’s age. Although desirable, no special training is required to
properly administer and score the PPVT. The PPVT provides
an estimate of the subject’s verbal performance and can be ad-
ministered to groups with reading or speech problems, mental
retardation, or if emotionally withdrawn. For its administra-
tion, the examiner presents a series of pictures to each subject.
There are four pictures to a page, and each is numbered. The
examiner states a word describing one of the pictures and asks
the client to point to or say the number of the picture that the
word describes. PPVT was standardized for Turkish language
by Katz and colleagues in 1974 (as cited in Oner, 1997). For
Turkish standardization, 1440 children (2 - 12 years) living in
urban, suburban and rural areas were tested and norm tables
were listed according to the scores. Reliability of Turkish stan-
dardization of PPVT was found to have range of .71 - .81.
Wisconsin Card Sorting Test (WCST): WCST is developed
by Berg (1948), and revised by Heaton (1981) to assess execu-
tive functions in terms of planning, organizing, abstract think-
ing, conceptualization, maintaining and adapting cognitive
constructs and inhibiting impulsive responses (Lezak, 1995;
Spreen & Strauss, 1998). WCST measures 13 different execu-
tive functioning abilities; number of total responses, number of
total errors, number of total correct responses, number of cate-
gories completed, number of perseverative responses, number
of total perseverative errors, number of nonperseverative errors,
percentage of perseverative errors, number of responses to
complete the set, number of conceptual level of responses, per-
centage of conceptual level of responses, failure to maintain a
set and learning to learn. Turkish standardization and validation
of WCST for adults was reported by Karakas, Eski and Basar
(1996) and for children between 6 - 15 ages (75 - 182 months)
by Erol et al. (2006).
The procedure was applied at the schools during day time
under the supervision of the teachers. Children were informed
about the purpose of the study and the voluntary nature of par-
ticipation was explained. None of the children refused to par-
ticipate in the study. School records were used for grouping
children with and without special education background. Chil-
dren with early special education background formed Group 1
and children without early special education background formed
Group 2. Even though Group 1 was expected to have better
language performance, both groups were tested with PPVT by
authors in order to assess their language performance before the
study procedure was applied. Thus, the data gathered from
Group 1 also points the group with “better language perform-
ance”. EF of the children were tested with WCST in the test
rooms of the schools where are silent rooms with minimum
materials which minimize the distraction of children. Children
were given stickers of stars and smiley faces to reward their
efforts and sustain motivation. The same numbers of stickers
were offered to each child, across the two groups. Care was
taken to give instructions with maximum clarity, making sure
that children could see the tester’s lip movements, and that their
attention was appropriately focused. The same instructions
R. F. SIPAL ET AL. 739
were given to all participants. Tests were always administered
in the same order, to ensure that potential test-order effects
would be constant across groups. Test materials were four
stimulus cards (from left to right; a red triangle, two green stars,
three yellow crosses and four blue circles) and the response
cards. Response cards were placed in an order as described in
the test manual. The researcher picked one of the response
cards and gave it to the child in order to match the correct
stimulus card. For each correct match, the child was prompted
as “correct” and for each false match the child was prompted as
“false”. First turn of matching was based on color, second turn
was based on shape and third turn was based on quantity. As
soon as the child successfully completed the first turn (match-
ing 10 cards according to their colors), matching criterion was
changed to “shape”. Similar to the first turn, for each correct
match the child was prompted as “correct” and for each false
match the child was prompted as “false”. Each session included
six turns as; color, shape, quantity, color, shape, quantity.
WCST sessions ended when the children successfully matched
the cards (10 for every category) in six matching categories
(color, shape, quantity, color, shape, quantity) or when the
cards ran out. Sessions took around 20 - 25 minutes for the chil-
dren participating in the study.
Preliminary analyses of the participants are shown in Table 1.
Table 2 provides the descriptive statistics for each group of
Preliminary analysis of the participants in the study.
Variable N % S M
10 19 % 23.2
11 16 % 19.5
12 15 % 18.3
13 17 % 20.7
14 15 % 18.3
Girl 40 % 48.8
Boy 42 % 51.2
Early special e ducation background
Had early special ed. 39 % 47.6
Did not have early special ed. 43 % 52.4
Duration of early special education
Never 43 % 52.4
Less than 1 year 10 % 12.2
1-2 years 5 % 6.2
2-3 years 2 % 2.4
More than 3 years 22 % 26.8
Communication choices with family
Sign language 16 % 19.5
Oral language 16 % 19.5
Both 50 % 50
Reactions to communication barriers
Repeatedly tries to express 63 % 76.8
Gets angry 10 % 12.2
Gives up 6 % 7.3
Other 3 % 3.7
Children’s performance on peabody picture vocabulary test.
PPVT raw scores PPVT standard scores
M SD M SD
Group 1a 39 56.3 14.4 67.2 11.7
Group 2b 43 50.1 12.7 48.4 14.3
Note. Standard scores based on a population M = 100, SD = 13. a. with early
special education background; b. without early special education background.
children on the language test. As hypothesized, a significant
effect of group emerged on children’s raw score on the PPVT
(F[2, 65] = 29.89, p < .001) Follow-up ANOVA with Bon-
ferroni corrections revealed that, as expected, Group 1 scored
significantly higher than Group 2 (F[1, 41] = 50.93, p < .001)
Correlations of WCST scores with language ability, gender
and age are presented in Table 3. Pre-analyses of data distribu-
tion showed that some of the WCST scores presented abnormal
distribution. Therefore, WCST scores which showed abnormal
distribution were analyzed with Mann-Whitney U and Wil-
coxon W tests and normally distributing scores were analyzed
with T test. Results showed that WCST scores 1, 2, 3, 4, 5, 6, 8,
11, 13 are significantly effected by language ability (p < .05).
Gender was found to have impact on all WCST scores but
WCST 7 and 10. Besides, age showed difference for only
WCST 7 (p = .005). Tukey’s post-hoc was applied for better
understanding the difference between ages. Results showed that
ages 10 and 14 differ for WCST 7 (mean scores difference = 7,
80, S = 2.84, p = .05).
Distribution of the mean scores gathered from WCST was
shown in Figure 1 for better understanding the WCST per-
formances of children in the study. There is a decreasing trend
in the mean scores which show that children in the study were
facing difficulties in most of the main WCST tasks such as
number of categories completed (WCST 4), number of nonper-
severative errors (WCST 7), number of responses to complete
the first set (WCST 9), learning to learn (WCST 13) and main-
taining a set (WCST 12). Conceptual level of responses in both
numbers and percentages were found relatively average (WCST
10 and 11).
High level cognitive processing abilities, also known as key
executive functions, include planning and organizational abili-
istribution of mean scores for each WCST subtest. D
R. F. SIPAL ET AL.
Analysis of language a b ility, age and gender compared t o WCST scores.
Language abil ity Gender Age
Whitney U Wilcoxon W F t p Mann
Whitney UWilcoxon WF t p X2 F p
WCST 1 566.0 1386.0 .002* 2.43 .657
WCST 2 23.52 –6.01 .003*486.5 1306.5 .001* 1.417.236
WCST 3 58.90 3.46 .001* 11.152.52 .014* 1.130.348
WCST 4 .005 946.0 .007* .12 4.15 .023* .244 .913
WCST 5 42.68 6.48 .009*469.0 1289.0 .001* 3.55 .469
WCST 6 42.63 –6.48 .001*460.0 1280.0 .004* 4.09 .393
WCST 7 4.69 .335 .738 2.73 –.77 .441 4.018.005*
WCST 8 46.88 –6.06 .013*549.5 1369.5 .007* 4.72 .396
WCST 9 1.12 –1.23 .221 .67 –2.49 .015* 1.126.351
WCST 10 678.5 1458.5 .965 664.0 1259.0 .862 2.107.089
WCST 11 379.0 1009.0 .001*462.5 1057.5 .018* 2.399.058
WCST 12 513.5 1293.5 .853 299.5 734.5 .001* 4.97 .290
WCST 13 2.56 13.97 .037* .59 2.37 .021* 1.207.318
Note: *p < .05 significance level.
ties. abstract thinking, formulation of effective strategies, estab-
lishment and maintenance of cognitive sets, and refraining from
impulsive trial-and error responses. Such executive functioning
requires the ability to draw upon existing knowledge and
strategies which are then applied to problem solving involving
the flow of information back and forth between cognitive and
metacognitive levels of processing (Butterfield et al., 1995).
Some researchers have suggested that the observed EF Table 3.
deficits of children with language delay or impairment imply
that language ability may play a significant role in executive
functioning (Singer & Bashir, 1999; Ylvisaker & De Bonis,
2000). The main hypothesis of this study was that language
ability would relate to performance on measures of executive
functioning differentially. The findings, in general, provide
support for this hypothesis.
Results of language ability were found to impact on execu-
tive functions. The findings illustrate that WCST 2, 3, 4, 5, 6, 8,
11 and 13 were significantly affected by language ability and
the group (1) with higher language skills was found to possess
higher levels of executive functioning. This finding links/cor-
relates with previous studies on executive functions and lan-
guage problems (Marlowe, 2000; Singer & Bashir, 1999; Landa
& Goldberg, 2005; Hooper et al., 2002). Hooper et al. (2002)
studied language skills and reported that impairments in lan-
guage results in impairments in executive functions. The paral-
lel finding in our study echoes the early studies and reveals that
children who are deaf have delays in executive functions and
better language abilities have a boosting effect in developing
executive functions. Besides, results show that WCST 7, 9, 10
and 12 had no significant affect on language abilities in our
sample. This finding is quite surprising as WCST 9 and 12
points out working memory which is highly related to language
skills. Such a result indicates that there may be some other fac-
tors affecting working memory than the language.
Surprisingly, the findings on WCST and gender presented
were at odds to those already cited in the literature (Surowiecki
et al., 2002; Miyake et al., 2000; Erol et al., 2006). All WCST
scores with the exception of WCST 7 and 10 were found to be
significantly affected by gender. Heaton (1993), Roselli and
Ardilla (1993) and Shu, Tien, Lung et al. (2000) reported that
gender has no significant affect on executive functioning.
Moreover, Erol et al. (2006), in the standardization of WCST
for Turkish children reported that gender has no effect on any
WCST scores. In our study, boys were found to have higher
executive skills compared to girls which show that girls have
poor perseveration skills. Such a finding may be an artifact of
the sampling process. In our study, we assessed a highly spe-
cific sample which may lead to biased findings because of the
characteristics of the participants. However, this result is
strongly considered by the authors as necessary to be assessed
in further studies.
Frontal lobes are well-known to be the latest developing
body structures both anatomically and in functionality and
therefore, their activities increase with age and reach their Ze-
nith during adolescence (Karakas, 2004; Kilic, 2002). Thus,
adolescents are expected to have higher levels of executive
functioning and positive WCST scores relative to school age
children/pre adolescents. In this study, only WCST 7 (number
of nonperseverative errors) was found to be affected by age
which shows that nonperseverative errors of children who are
deaf decrease with age and which is in keeping with previously
published studies (Heaton, 1993; Roselli & Ardilla, 1993; Erol
et al., 2006). This finding highlights the importance of devel-
opmental features. During normal development children ach-
ieve their highest level of executive functioning around 11 age,
children who are deaf display delays in the development of this
executive functioning and only possess the EF of a 10 years old
child when they are between 12 - 14 ages. Such a difference
R. F. SIPAL ET AL. 741
highlights the importance of language skills on the develop-
ment of EF. As children learn to control their behaviors and
flexibly correct their actions with social feedbacks (Hughes &
Graham, 2002), thus the lack of receiving insufficient feedback
due to low language skills affects their ability to learn to control
their responses. As a result one can say that “lack of practicing”
self regulatory skills lead to delays in the development of EF.
Findings of our study presents that language ability has im-
pact on executive functions of children who are deaf. From a
theoretical perspective, the findings support the interdepend-
ence of language and executive functions but also suggest that
executive functions themselves may be dissociable. Therefore,
one can say that early language skills have positive effects on
cognitive development of children who are deaf.
Besides, it is argued that the behavioral manifestations of
executive function delays observable in deaf children are un-
likely to be the consequences of deafness itself but rather result
from the language delays that are the consequences of the
deafness. The finding that deaf children experience deficits in
executive functions has both clinical and educational implica-
tions. Clinical assessment of deaf children should take into
account their potential difficulties with executive functions and
the ways in which this might interfere with their performance in
other areas, including both the cognitive and social domains.
Deficits in executive functions may manifest in difficulties in
organizing thoughts for writing tasks, organizing materials for
lessons or homework, organizing time, and implementing
lengthy verbal instructions. Poor executive functioning may
also show behaviorally through difficulties in social situations,
such as expressing the self and peer interactions. Behavioral
management and classroom teaching may be facilitated by us-
ing learning strategies that emphasize visual cues and place
minimal demands on language, so that deaf children’s execu-
tive functioning can be maximized. In addition, enhancing par-
ticular aspects of language use, such as teaching deaf children
to practice and implement self talk strategies for planning and
problem solving, may help them make better use of their exist-
ing executive functioning and develop them more fully.
Limitations and Implications for Further Studies
This study was an attempt to assess the executive functions
of children who are deaf and to clarify the linking to their lan-
guage abilities. As some of the findings echo the earlier re-
search, present study poses several questions which will require
further research and evaluation.
The limited number of participants in the study has the risk
of presenting biased results as well as decreasing weighting of
the findings. Of the small sample size (82 children) means that
the findings may reflect the characteristics of the participants,
their cultural background or the structure of their social envi-
ronment. A further study with a larger sample may present
more accurate results.
Children with disabilities differ within their groups as they
may have different levels of severity in their disability. Particu-
larly for children who are deaf, there are numerous educational
options according to their hearing and language abilities that
support their development. As different educational back-
grounds may cause differences in their developmental pace,
including a particular group (only with severe hearing loss or
only profound hearing loss) in a study may result in limited
findings which are not comparable. Therefore, a future study
including children who are deaf from different levels of hearing
loss would provide deeper understanding of their executive
Our study provides information on the development of ex-
ecutive functioning of children who are deaf. However, our
findings are limited to a small range of age group. A further
study including a wide range of age group (i.e. 6 - 12 ages) may
provide clearer results on the development of the executive
functions of children who are deaf. Besides, a comparison
group would provide precious information on their develop-
mental pathways in terms of executive functioning.
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