Running head: EFFORTFUL CONTROL AND NEGATIVE AFFECTIVITY
Implications of Effortful Control and Negative Affectivity
in the Persistence and Recovery of Stuttering
Stephanie Hitti
Vanderbilt University
This study was completed in partial fulfillment of the requirements for Honors in Psychology at
Vanderbilt University under the direction of Tedra A. Walden.
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Abstract
The present study investigated the differences in Negative Affectivity and Effortful Control in
the presence and absence of stuttering. A Speech Language Pathologist (SLP) measured the
stuttering-like disfluencies (SLDs) of 92 preschool-aged participants at two separate time points
(i.e. time point 1 and time point 2). The participants were then divided into four stutter groups:
children who did not stutter at either time point (CWNS), children who stuttered at both time
points (Persistent), children who stuttered at time point 1 but did not stutter at time point 2
(Recovered), and children who did not stutter at time point 1 but stuttered at time point 2
(Transitional). Results indicated that at time point 1, both the Recovered and the Persistent group
had significantly lower scores of Effortful Control on the Children’s Behavior Questionnaire
(CBQ) than the CWNS group. Additionally, both the Persistent and the Transitional groups had
significantly higher Negative Affectivity scores on the CBQ at time point 1 than at time point 2,
but the other groups did not.
Keywords: stuttering, temperament, effortful control, negative affectivity
EFFORTFUL CONTROL AND NEGATIVE AFFECTIVITY
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This study explored the relation between effortful control (EC), negative affectivity
(NA), and the persistence and recovery of stuttering. Stuttering, a communication disorder that
affects fluency of speech, tends to begin during childhood and, in about 1% of people, can last a
lifetime. It is characterized by disfluencies, such as repetitions and prolongations of sounds,
which may impede communication. Approximately 5% of all children stutter at some point in
their lives, usually beginning between the ages of 2 and 5, as their language skills begin to
develop (National Institute on Deafness and Other Communication Disorders, 2015). Moreover,
there are about 3 to 4 times more boys than girls who stutter. While no single cause for stuttering
has been established, there are some speculations that the influences of genetics, speech and
motor factors, and temperament/emotions may be related (Andrews, 1991; Kent, 2001; Jones,
Choi, Conture, & Walden, 2014). Recently researchers have been investigating the relation
between elements of temperament, such as inhibitory control and attention regulation, and
stuttering (Eggers, De Nil, & Van den Bergh, 2010). However, although data suggest that both
variables are indeed related to stuttering, most research focuses on correlations, not causality
(Conture, Kelly, & Walden, 2013). The first step in obtaining evidence of causality would be,
ideally, to measure temperament before stuttering commences since random assignment of
groups is not possible. In order to obtain such data, a very large sample would be necesary.
Therefore, to the present authors’ knowledge, there is no study that has measured temperament in
preschool-aged children before the onset of stuttering.
Stuttering is diagnosed by speech-language pathologists (SLPs) who are trained to detect
language disfluencies such as whole word repetitions (WWR), single syllable repetitions (SSR),
prolongations, interjections, and revisions. Most SLPs diagnose stuttering by considering both
the frequency of stuttering-like disfluencies per 100 words and the Stuttering Severity Instrument
EFFORTFUL CONTROL AND NEGATIVE AFFECTIVITY
4
(SSI) (e.g., Yari, 1981; Yari & Ambrose, 1992b; Yari & Lewis, 1984). A child is usually
considered to stutter if he has 3 or more disfluencies per 100 words and has a score of 11 or
higher on the SSI (Karrass et al., 2003). However, some researchers solely rely on the frequency
of stuttering-like disfluencies per 100 words to diagnose stuttering (Conture & Caruso, 1987;
Riley, 1980). SLPs can also predict whether or not the child is likely to continue to stutter and
whether his or her parents should consider treatment. Although there is no single factor that can
be used to predict the continuation of stuttering, family history and presence of other speech or
language disorders can help SLPs make that decision (National Institute on Deafness and Other
Communication Disorders, 2015).
Previous literature has found that aspects of temperament may influence communication
in children who do not stutter. For example, Dixon and Shore (1997) found a predictive relation
between early temperamental aspects (e.g. soothability) and later linguistic style, further
establishing the link between language and temperament. Their findings indicated that greater
adaptability, increased positive mood, and greater persistence at 13 months predicted advanced
language productivity at 20 months. Data also suggest that there is a relation between
temperament characteristics and communication disorders such as developmental stuttering
(Anderson, Pellowski, Conture, & Kelly, 2003; Lewis & Goldberg, 1997; Embrechts, Ebben,
Franke, & van de Poel, 2000).
Specifically, researchers have proposed that stuttering, as well as other speech-language
disorders, such as late talking and specific language impairment, are directly influenced by the
temperamental dimensions of NA and EC (Salley & Dixon, 2007; Johnson, Walden, Conture, &
Karrass, 2010; Ntourou, Conture, & Walden, 2013; Felsenfeld, van Beijsterveldt, & Boomsma,
2010; Embrechts et al., 2000). The present study will focus on the scales of NA and EC of the
EFFORTFUL CONTROL AND NEGATIVE AFFECTIVITY
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Children’s Behavior Questionnaire (Rothbart et al., 2001) and will explore their relation to
childhood stuttering.
NA is a temperament characteristic that refers to “the stable tendency to experience
negative emotions” (Watson & Clark, 1984). People high in NA tend to report consistent
negative moods. NA envelops a range of negative mood states: discomfort, sadness, fear and
anger or frustration, and belongs to the broader concept of emotional reactivity, or “the tendency
to experience frequent and intense emotional arousal” (Karrass et al., 2006, p. 403).
Salley and Dixon (2007, p.137) expressed that, “when children are very high in NA, a
relatively greater burden is placed on their behavioral control systems, which must regulate this
NA. The end result is fewer resources available for linguistically relevant activities such as
paying attention to word-referent associations when learning novel labels.” Others have also
found that CWS are more negative in affect and emotions (Howell, Davis, Bartrip, & Wormald,
2004; Johnson, Walden, Conture, & Karrass, 2010; Ntourou, Conture, & Walden, 2013). For
example, Ntourou, Conture, and Walden’s (2013) findings indicate that CWS displayed
significantly more negative emotions and more self-speech than their CWNS peers when
completing a frustrating task, namely the “Attractive Toy in a Transparent Box” (ATTB) task
from Goldsmith, Reilly, Lemery, Longley, and Prescott (1999). These results are consistent with
the idea that preschool-aged CWS are more emotionally reactive than CWNS and that stuttering
is related to NA.
Moreover, the literature has consistently found that CWS are more nervous, anxious, shy,
and withdrawn than CWNS (Fowlie & Cooper, 1978). In particular, Glanser et al (1949) found
that CWS are more self-conscious and anxious when it comes to speaking than their CWNS
peers. This anxiety or frustration was apparent as the participants would cry, whisper “I can’t
EFFORTFUL CONTROL AND NEGATIVE AFFECTIVITY
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talk,” stomp their feet, and/or walk away without completing their sentences. These findings,
again, indicate that stuttering may be associated with the NA factor of the CBQ, specifically the
Fear and Anger/Frustration characteristics of temperament.
Theorists have also found that CWS have a tendency to be more sensitive and possess
more vulnerable temperaments (i.e. fearful/shy), when compared to CWNS (Anderson et al.,
2003). This indicates that there might be a relation between stuttering and temperamental
sadness, “the amount of negative affect and lowered mood and energy related to exposure to
suffering, disappointment, and object loss” (Van den Bergh and Ackx, 2003). Johnson, Walden,
Conture, and Karrass (2010) investigated emotional regulation in CWS and CWNS when
receiving either a desirable or an undesirable gift. Their findings demonstrated that, while CWS
and CWNS displayed no difference in positive emotion upon receiving the desirable gift, CWS
displayed significantly more negative emotion upon receiving the undesirable gift. This, again,
provides support to the possibility of a relation between the temperamental characteristic of
“sadness” and stuttering. Others have also implied that such sensitivity and vulnerability may
contribute to the onset or continuation of developmental stuttering (Conture, 1991;2001; Guitar,
1998; Zebrowski & Conture ,1998).
Rothbart and Rueda (2005) defined EC as the "efficiency of executive attention,
including the ability to inhibit a dominant response and/or to activate a subdominant response, to
plan, and to detect errors." In other words, EC is one’s ability to independently manage attention,
inhibit undesirable behavior, and activate desirable behavior (Eisenberg, 2012). Represented in
the concept of EC are attentional focusing, attentional shifting, and inhibitory control;
characteristics that have been repeatedly found to be lower in preschool-aged CWS (Felsenfeld,
van Beijsterveldt, & Boomsma, 2010; Embrechts et al., 2000; Kraft, Ambrose, & Chon, 2014;
EFFORTFUL CONTROL AND NEGATIVE AFFECTIVITY
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Reilly, Onslow, & Packman, 2013; Schwenk, Conture, & Walden, 2007). Specifically, Rothbart
et al. (2001) defined attentional focusing as the “tendency to maintain attentional focus upon
task-related channels,” attentional shifting as the ability to change one’s focus from one item to
another, and inhibitory control as “the capacity to plan and to suppress inappropriate approach
responses under instructions or in novel or uncertain situations.”
Effective EC includes the ability to regulate one’s emotion, therefore, the fact that
researchers have found a relation between emotional regulation and stuttering (Dixon & Smitth,
2000; Kefalianos, Onslow, Block, Menzies, and Reilly, 2012) suggests that there should be a
relation between EC and stuttering. A common regulatory strategy is attention regulation, or the
ability to control one’s attention in order to limit the emotional effect a stimulus may arouse
(Ahdahi & Rothbart, 1994). Attention regulation has consistently found to be related to
childhood stuttering (e.g., Schwenk, Conture, & Walden, 2007).
Karrass et al. (2006) investigated the relation between emotional reactivity and emotional
regulation to childhood stuttering. CWS were more emotionally reactive to environmental
stimuli and less able to regulate their emotions than their fluent peers. Likewise, Embrechts et
al.’s (2000) findings suggest that CWS are less able to regulate their attention and adjust to their
environment. Several other studies, such as Kefalianos et al. (2012), found that CWS tend to
have lower attention spans and persistence as well as a more negative quality of mood. Similarly,
Rothbart and Rueda (2005) found that among U.S. children, EC is inversely correlated with NA.
Some researchers have found that CWS have a more difficult time disengaging their
attention when asked to do so or when it becomes appropriate to do so (Bush, 2006), as well as
difficulty shifting their attention when the need arises (Eggers et al., 2010). Moreover,
Felsenfeld, van Beijsterveldt & Boomsma (2010) found that caregivers of CWS are more likely
EFFORTFUL CONTROL AND NEGATIVE AFFECTIVITY
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to report more attention problems on parent questionnaires. Theorists have also reported that
CWS can be more reactive to environmental stimuli, making them less able to keep focused on a
particular task (Wakaba, 1998).
However, there have been some disparities in the literature. Johnson, Conture, and
Walden (2012) did not find that CWS were less apt at regulating their attention than CWNS.
This divergence could be explained by the fact that most other studies used data from parental
reports, whereas Johnson et al. (2013) examined response speed and accuracy during an
experimental task intending to measure attention. Anderson, Pellowski, Conture and Kelly
(2003) reported that CWS were more hypervigilant, or less likely to be distracted than CWNS
peers. This study is particularly inconsistent with that of Embrechts et al. (2000) who found that
CWS are more distractible and less able to focus than CWNS. Anderson et al. (2003) suggested
that these inconsistencies may be due to the fact that Embrechts et al.’s (2000) study was
conducted with Dutch children and there may be a cultural difference. Moreover, Embrechts et
al. (2000) used the CBQ whereas Anderson et al. (2003) used the Behavioral Style Questionnaire
(BSQ). Anderson et al. proposed that it would be wise to use both the BSQ and the CBQ in
future studies.
On the other hand, Johnson, Conture, Walden & Karrass (2012) theorized that attention
regulation in CWS may vary depending on stuttering severity. Their findings indicate that
children who have a mild stutter may be more able to regulate their emotions than children who
have a moderate to severe stutter. Thus, it may be that the studies mentioned above did not find
differences in attention regulation between CWS and CWNS because they did not account for
stuttering severity.
Research hypotheses
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Therefore, there is sufficient evidence in the literature to suggest that there might be a
relation between NA and EC in CWS and CWNS. With the use of the CBQ, the present study
explored this relation in the context of four different stutter groups at two time points separated,
in most cases, by a period of eight months. The groups were: children who did not stutter at
either time point (CWNS), children who stuttered at both time points (Persistent), children who
stuttered at time point 1 but did not stutter at time point 2 (Recovered), and children who did not
stutter at time point 1 but stuttered at time point 2 (Transitional).
First, it was hypothesized that the two groups that stuttered at time point 1, Persistent and
Recovered, would have (1) lower scores on EC and (2) higher scores on NA than the two groups
that did not stutter at time point 1, CWNS and Transitional. Similarly, it was hypothesized that
the two groups that stuttered at time point 2, Persistent and Transitional, would have (1) lower
scores on EC and (2) higher scores on NA than the two groups that did not stutter at time point 2,
CWNS and Transitional. Second, it was predicted that the participants in the Transitional group
would have (1) higher scores of EC and (2) lower scores of NAat time point 1 than at time point
2. Third, it was hypothesized that the participants in the Recovered group would have (1) lower
scores of EC and (2) higher scores of NA at time point 1 than at time point 2.
Methods
Participants
Participants consisted of 60 preschool aged boys and 32 preschool aged girls, all native
speakers of American English. Participants were involved in a several studies conducted by
Vanderbilt University's Developmental Stuttering Project.
Participants were divided into four groups according to whether or not they stuttered at
time point 1 and at time point 2: CWNS (15 girls and 15 boys), Persistent, (15 boys and 2 girls),
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Recovered (23 boys and 7 girls), and Transitional (7 boys and 8 girls). For the majority of the
participants (85), the time points were separated by a period of 8 months. However, due to
missed appointments, 6 participants had 15-17 months between visits, and one had 25 months
between time point 1 and time point 2. An analysis of variance (ANOVA) reveled significant
differences in gender (F(3,88) = 4.00, p = .01), which was expected due to the fact that three to
four times more boys than girls who stutter.
Participants were between the ages of 2;11 (years; months) and 6;4 at time point 1
(CWNS: M = 48.87, SD = 7.87; Persistent: M = 46.53, SD = 6.75; Recovered: M = 49.43, SD =
10.02; Transitional: M = 47.93, SD = 11.13) with no significant difference in age, F(3, 88) = .41,
p = .74, and between the ages of 3;7 and 7;0 at time point 2 (CWNS: M = 57.43, SD = 7.80;
Persistent: M = 57.24, SD = 8.76; ; Recovered: M = 58.80, SD = 10.72; Transitional: M = 56.53,
SD = 10.79) with no significant difference in age, F(3,88) = .23, p = .88.
All participants were paid volunteers referred to the Vanderbilt Bill Wilkerson Center by
their caregivers. Recruitment occurred through (a) advertisements in a free parent-orientated
magazine based in Middle Tennessee (e.g. the “Nashville Parent), (b) referrals from Nashville
area speech-language pathologists, health care providers, researchers, and day cares, (c) or self or
professional referral for initial assessment for childhood stuttering. Some participants reported
having received formal or structured treatment for stuttering. Participants had no known or
reported developmental, academic, hearing, intellectual, neurological, or emotional problems.
Each participant’s caregiver signed informed consent and each participant assented.
Classification
Children who do not stutter (CWNS). A child was considered a CWNS if he or she
displayed less than three stuttering-like disfluencies (i.e., sound prolongations, sound/syllable
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repetitions, monosyllabic whole-word repetitions, and broken words) per 100 words during a
play-based conversation (from a 300-word sample; Conture, 2001) at both time point 1 (M =
1.25, SD = .71) and time point 2 (M = 1.19, SD = .74).
Persistent. A child was considered Persistent if he or she displayed three or more
stuttering-like disfluencies per 100 words during a play-based conversation (from a 300 word
sample) at both time point 1 (M = 9.22, SD = 4.98) and at time point 2 (M = 7.40, SD = 4.88).
Recovered. A child was considered Recovered if he or she displayed three or more
stuttering-like disfluencies per 100 words during a play-based conversation (from a 300 word
sample) at time point 1 (M = 5.89, SD = 3.35) but displayed less than three stuttering-like
disfluencies per 100 words of a play-based conversation (from a 300 word sample) at time point
2 (M = 1.40, SD = .74).
Transitional. A child was considered Transitional if he or she displayed less than three
stuttering-like disfluencies per 100 words during a play-based conversation (from a 300 word
sample) at time point 1 (M = 2.0, SD = .85) but displayed three or more stuttering-like
disfluencies per 100 words of a play-based conversation (from a 300 word sample) at time point
2 (M = 4.56, SD = 2.86).
Excluded Participants
From an initial group of 147 participants, 55 participants were excluded (43 CWNS, 1
Transitional, 3 Persistent, and 8 Recovered). The main reason for exclusion was an incomplete
CBQ at either time point, (23 participants; 11 CWNS, 1 Transitional, 3 Persistent, and 8
Recovered). Thus, 124 participants had a complete CBQ at both time point 1 and time point 2
(62 CWNS, 15 Transitional, 17 Persistent, and 30 Recovered). All 15 Transitional, 17 Persistent,
EFFORTFUL CONTROL AND NEGATIVE AFFECTIVITY
12
and 30 Recovered participants were included in the study. However, to make the groups roughly
equivalent in number, 15 girls and 15 boys were randomly selected from the 62 CWNS.
Standardized speech-language tests and hearing screening
To participate in this study, each participant must have scored above the 16th percentile or
higher on a series of standardized speech-language tests: (a) Peabody Picture Vocabulary TestThird or Fourth Edition (PPVT-III or IV A or B; Dunn & Dunn, 1997, 2007), a measure of
receptive vocabulary, (b) Expressive Vocabulary Test First or Second Edition (EVT or EVT-2;
Williams, 1997, 2007), a measure of expressive vocabulary, (c) Test of Early Language
Development-3 (TELD-3; Hresko, Reid, & Hamill, 1999), a measure of receptive and expressive
language, and (d) “Sounds in Words” subtest of the Goldman-Fristoe Test of Articulation-2
(GFTA-2; Goldman & Fristoe, 2000). Additionally, each child passed a bilateral pure tone
hearing screening and tympanometric screening. All tests were conducted at the Vanderbilt Bill
Wilkerson Center.
Race
The participants’ race was obtained through a parent interview. The CWNS group
included 23 Caucasian, 4 African American, and 2 biracial participants; the Persistent group
included 12 Caucasian, 2 African American, 1 biracial, and 1 Asian participant; the Recovered
group included 26 Caucasian, and 4 biracial participants; and the Transitional group included 14
Caucasian and 1 African American participant. Three participants, 2 CWNS and 1 from the
Persistent group, opted to not disclose their race.
Measures
The Children’s Behavior Questionnaire (CBQ) assesses temperament of preschool-aged
children (ages 3 to 7) along 15 temperamental characteristics or scales. The temperamental scales
EFFORTFUL CONTROL AND NEGATIVE AFFECTIVITY
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make up three composite higher order factors: Effortful Control (EC), Negative Affectivity
(NA), and Extraversion/Surgency. Detail is provided in Table 1.
This study focused on the higher order factors of EC and NA (excluding
Extraversion/Surgency) because several participants lacked scores in the Extraversion/Surgency
scales as their parents completed the short version of the CBQ (70 questions) instead of the
longer version (237 questions). Parents rated each item from 1 (“extremely untrue of your child”)
to 7 (“extremely true of your child”). Scale scores were calculated by averaging the item scores.
Examples of EC items include “is hard to get her/his attention when s/he is concentrating on
something” and “can easily shift from one activity to another.” Examples of NA items include
“has temper tantrums when s/he doesn’t get what s/he wants” and “tends to feel ‘down’ at the
end of an exciting day.”
Procedures
Parents completed an online questionnaire (CBQ) and speech language pathologists
(SLPs) measured the participants’ stuttering-like disfluencies (SLDs) at two different time
points. At each time point, SLPs listened to a total of 300 words in a play-based conversation and
recorded the SLDs. If the participant had 3 or more SLDs per 100 words, s/he was considered to
stutter; if s/he had less than 3 SLDs per 100 words, s/he was considered to not stutter. Each visit
also included a parental interview, the language and vocabulary tests (i.e. PPVT, EVT, TELD)
and a hearing test. Each visit took place at the Bill Wilkerson Center at Vanderbilt’s Medical
Center and lasted approximately 2 hours. Parents completed the questionnaires before arriving
and were given information about their children's performance on the speech, language, and
temperament assessments at the end of the visit.
Data Analyses
EFFORTFUL CONTROL AND NEGATIVE AFFECTIVITY
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Group differences in gender and age, at both time point 1 and time point 2, were assessed
using t-tests. Statistical tests of the hypotheses are described below.
Between-groups comparisons. A One Way Analysis of Variance (ANOVA) was
conducted across all groups to determine whether NA and EC, as well as all their respective
scales, differed among the groups at either time point 1 and time point 2. The independent
variable was the stutter group (i.e. CWNS, Persistent, Recovered, or Transitional) and the
dependent variable was the score each participant received in each variable of the CBQ. Next,
pairwise t-tests for significant differences determined which groups differed.
Within-groups comparisons. Repeated Measures ANOVA and ANCOVA, with gender
as a covariate, assessed whether the groups differed at time point 1 and time point 2, while
controlling for gender. The independent variables were the stutter groups and time points (i.e.
time point 1 or time point 2). The dependent variable, again, was the score each participant
received in each variable of the CBQ.
Results
Descriptive Statistics
Levene’s test of equality of error variances was conducted in order to ensure equality of
variance among groups. Additionally, to ensure homogeneity of variance, frequency distribution
graphs were created. Group means for NA and EC scores are in Table 2. Scores all showed
normality and homogeneity of variance. Additionally, Levene’s test of equality of error variance
reveled no significance on EC at time point 1 (F = .57, p = .64), EC at time point 2 (F = .30, p =
.83), NA at time point 1 (F = .63, p = .42), or NA at time point 2 (F = .42, p = .74).
Pearson’s correlations evaluated the relation between EC and NA at both time points.
There was significant negative correlations between NA at time point 1 with EC at time point 1
EFFORTFUL CONTROL AND NEGATIVE AFFECTIVITY
15
(r(92) = -.22, p = .03), and positive correlation between NA at time point 1 with NA at time point
2 (r(92) = .56, p < .001), and EC at time point 1 with EC at time point 2 (r(92) = .65, p < .001).
Between-group differences
ANOVA with gender as a covariate revealed between group differences in EC at both
time point 1 (F(4,87) = 2.55, p = .04) and time point 2 (F(4, 87) = 3.04, p = .03). Results are
illustrated in Figures 1 and 2. No between-group differences were found in NA at either time
point 1 (F(4,87) = 1.07, p = .27) or time point 2 (F(4,87) = 3.04, p = .436). These results are in
Figures 3 and 4.
Fisher’s least significant differences (LSD) were conducted as post hoc tests for EC
scores at time point 1 and time point 2. Results are shown in Table 3. As expected, at time point
1 the Persistent and the CWNS groups were significantly different (p = .02). This difference was
replicated in time point 2 (p = .003). Finally, at time point 1 there was a significant difference
between the Recovered and the CWNS groups (p = 0.02), but no difference at time point 2. This
was expected as, at time point 1 the Recovered group stuttered and the CWNS did not stutter, but
at time point 2, neither group stuttered.
Within-group differences
Repeated measures multivariate analyses of variance (MANOVA) assessed the
hypothesis that the Transitional children would have higher EC at time point 1 than at time point
2 and the hypothesis that the Transitional groups would have lower NA at time point 1 than at
time point 2. The effect of time was significant for NA (p < .01), supporting the hypothesis.
However, the effect of time was not significant for EC (p = .62). These findings did not support
the hypotheses.
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16
Additionally, the results reflected a significant effect of time on NA in the Persistent
group (p = .01). Results are illustrated in Figure 5 for NA and Figure 6 for EC. No other groups
differed between time points. Finally, repeated measures analyses with two main effects (group
and time) and one interaction term (group x time) indicated that for NA scores collected at time
point 1 and time point 2, the effect of time and time x gender were significant: p < .05 and p< .05
respectively, but no differences in EC. While a time x gender effect would call for further
analyses, as the Persistent group contains only 2 girls and 15 boys, further analyses are not
possible. In the Persistent group, the mean of NA for girls was 2.57 at time point 1 and 4.10 at
time point 2 and for boys was 3.79 at time point 1 and 4.29 at time point 2. Thus, while NA
increased at time point 2 for both sexes, the increase was more dramatic for girls.
Discussion
The present study’s primary purpose was to investigate the relation between EC, NA, and
developmental stuttering. It extends previous research on the study of temperament and
stuttering as it examines persistence and recovery from stuttering instead of solely the presence
or lack of stuttering. Researchers have commented on the heterogeneity of the CWS group
(Blood, Ridenour, Qualls, & Hammer, 2003), yet few studies explore differences within the
CWS group. By creating subgroups of CWS group (i.e. Persistent, Recovered, and Transitional),
this study goes beyond the CWNS and CWS comparison, increasing the current understanding of
the relation between temperament and the persistence and recovery from stuttering.
Main findings: An overview
The study resulted in three main findings. First, at time point 1, children in the Recovered
and Persistent groups differed in EC from the CWNS group. At time point 1 both the Recovered
and Persistent groups stuttered, suggesting that children who stutter differ from children who do
EFFORTFUL CONTROL AND NEGATIVE AFFECTIVITY
17
not stutter in EC. This is consistent with previous literature and supports the present study’s first
hypothesis. Second, at time point 2 only the Persistent group differed from the CWNS group in
EC. That is, when the Recovered group stopped stuttering, they no longer differed from the
CWNS group. Third, findings indicate that both the Persistent and Transitional groups scored
higher in Negative at time point 2 than at time point 1. While it was hypothesized that the
Transitional group would have higher NA at time point 2 than at time point 1, this was not
hypothesized for the Persistent group.
Differences in Effortful Control
While EC improves significantly throughout childhood, there are large individual
differences in this dimension of temperament. These differences may be influenced by both
biological and environmental factors. EC, or self-regulation, is related to the control of thoughts
and feelings, as well as the ability to resolve conflicts (Rothbart & Bates, 2006). This aspect of
temperament is, thus, important, as children who are not able to regulate themselves tend to
stimulate negative reactions from others (Posner & Rothbart, 2007). Additionally, the skills
involved in EC are important for learning and social competence (Eisenberg, Valiente, &
Eggum, 2010; Eisenberg, Eggum, Vaughan, & Edwards, 2010).
Between-group differences. While at time point 1 the Persistent and the Recovered
group differed from the CWNS group in EC, they did not differ from the Transitional group. One
explanation for this could be that the participants in the transitional group were in the process of
developing a stutter and, thus, were not different from the groups who did stutter (i.e. the
Persistent and Recovered groups). Additionally, while at time point 2 the Persistent group
differed from the CWNS group in EC, it did not differ from the Recovered group. It was also
hypothesized that the Transitional group would differ from both the Recovered and the CWNS
EFFORTFUL CONTROL AND NEGATIVE AFFECTIVITY
18
groups at time point 2 and findings did not support this hypothesis. This may be due to the
instability of both the Recovered and the Transitional groups. The exact time that the participants
in these groups stopped or began to stutter was unknown. Thus, it is possible that a participant
who had stopped or began to stutter 7 months prior would differ in EC from a participant who
had only just stopped or began to stutter.
Within-group differences. While it was hypothesized that the Transitional group would
have higher EC at time point 1 than at time point 2, the results of the present study did not
support this. The results also did not support the hypothesis that the Recovered group would have
lower EC at time point 1 than at time point 2. A possible explanation for these findings may be
that the Recovered and the Transitional groups were in the process of change and, thus, highly
unstable. Additionally, EC was obtained through caregiver report and may be influenced by
extraneous variables. For example, as children age parents expect them to have greater EC and, if
their expectations are not met, their judgment may be affected. Similarly, as many participants
were entering the school system at the time of this investigation, more was expected from them.
Thus, parents may be judging them to be lower in EC compared to similar-aged peers.
Differences in Negative Affectivity
Between-group differences. Whereas previous literature has found that children who
stutter are more negative in their affect than children who do not stutter (e.g. Howell, Davis,
Bartrip, & Wormald, 2004; Johnson, Walden, Conture, & Karrass, 2010; Ntourou, Conture, &
Walden, 2013), the results of the present study did not support this. Specifically, it was
hypothesized that at time point 1 the Recovered and Persistent groups (who both stuttered at time
point 1) would have higher NA than the CWNS and Transitional groups (who did not stutter at
time point 1). It was also hypothesized that at time point 2 the Persistent and Transitional groups
EFFORTFUL CONTROL AND NEGATIVE AFFECTIVITY
19
would have higher NA than the CWNS and Recovered groups. However, findings did not
support these hypotheses. This, again, may be a result from the instability of the Transitional and
the Recovered groups. Moreover, as there were only 15-20 participants per group, the study
lacked power and may have failed to detect an effect that may actually exist.
Within-group differences. As hypothesized, the Transitional group had higher NA at
time point 2 than at time point 1. A possible explanation for these findings is that as participants
in this group developed a stutter, they may have become frustrated with their speech and, thus,
more negative in affect. Moreover, they may be teased by peers, which would again influence
their affect. Findings also indicated that participants in the Persistent group also had higher NA
at time point 2 than at time point 1. While this was not hypothesized, these findings may be due
to the fact that many participants started school between time point 1 and time point 2. An
increase in peer interaction could be stressful and increase negative emotions. Another possible
explanation for this finding is that as participants in the Persistent group would have been
stuttering for a longer period of time at time point 2 than at time point 1, they may have been
more frustrated with their speech and become more negative in affect. Finally, while it was
hypothesized that the Recovered group would have lower NA at time point 2 than at time point
1, results did not support this. Perhaps negative emotions that arise from stuttering may persist
even after the stuttering is gone. Research has found that children who stutter are more likely to
be rejected by their peers and are less popular (Davis, Howll, & Cooke, 2002). The negative
affect that arises from this is unlikely to change within months of the termination of stuttering.
Limitations and future directions
The present study had several limitations. First, as there were only 15-30 participants per
group, the study lacked power. Thus, an effect that may have actually existed may not have been
EFFORTFUL CONTROL AND NEGATIVE AFFECTIVITY
20
detected (a type 2 error). Future research should aim to have more participants per group to avoid
this. However, to increase the number of Transitional participants (i.e. did not stutter at time
point 1 and stuttered at time point 2), a very large sample would be needed, as only 3-5% of the
population stutters. Second, the results from this study are based on the report of a single parent
or caregiver as well as a single testing instrument, the CBQ. As parents may be influenced by
social desirability bias, future research should strive to obtain multiple reports from multiple
sources (e.g. parent, clinician, and teacher reports; observations home or in the laboratory; and
physiological data such as cortisol levels or heart rate). Third, while most participants’ parents
completed the longer version of the CBQ (237 questions), a number of participants completed
the shorter version of the CBQ (70 questions). Although both tests are known to assess the same
variables of EC and NA, future studies should maintain the version of the CBQ constant.
Moreover, participants were said to stutter or not stutter based on the amount of SLDs per
100 words as determined by one SLP. While there is high inter-rater reliability within the SLPs
in the study, future research should assess participants in different contexts and use different
instruments (e.g. the SSI) to determine whether or not he or she stutters. Using multiple criteria
has the advantage of a more accurate diagnosis. However, it has the potential of excluding
participants who are in a transitional period and don’t satisfy multiple criteria. Finally, while in
most cases, time point 1 and time point 2 was divided by a period of eight months, this period
was longer for 7 of the participants. Future research should control for time between time points.
Conclusions
The present findings indicate that children who stutter differ from children who do not
stutter in terms of EC and NA. Moreover, children who persisted stuttering, recovered from
stuttering, or are in the process of developing a stutter, differ in EC and NA. These differences
EFFORTFUL CONTROL AND NEGATIVE AFFECTIVITY
21
suggest that there is a relation between aspects of temperament and the persistence and recovery
from stuttering. Thus, the findings of the present study are essential in understanding the role that
EC and NA play in the development and maintenance of stuttering in preschool-aged children.
EFFORTFUL CONTROL AND NEGATIVE AFFECTIVITY
22
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EFFORTFUL CONTROL AND NEGATIVE AFFECTIVITY
Tables and Figures
Figure 1
Effortful Control Scores at Time Point 1
Effortful Control score on CBQ
5.1
5
4.9
4.8
4.7
4.6
4.5
4.4
4.3
4.2
4.1
4
Persistent
Transitional
CWNS
Recovered
Stutter Group
Note: Persistent and Recoverd groups differed from CWNS group
Figure 2
Effortful Control Scores at Time Point 2
Effortdul Control Score on CBQ
5
4.9
4.8
4.7
4.6
4.5
4.4
4.3
4.2
4.1
4
Persistent
Transitional
CWNS
Stutter Group
Note: Persistent group differed from CWNS group
Recovered
30
EFFORTFUL CONTROL AND NEGATIVE AFFECTIVITY
Figure 3
Negative Affectivity Scores at Time Point 1
Negative Affectivity score on CBQ
4.2
4.1
4
3.9
3.8
3.7
3.6
3.5
3.4
3.3
Persistent-
Transitional
CWNS
Stutter Group
Recovered
Note: Groups did not differ
Figure 4
Negative Affectivity Scores at Time Point 2
Negative Affectivity Score on CBQ
4.4
4.3
4.2
4.1
4
3.9
3.8
3.7
Persistent
Transitional
CWNS
Stutter Group
Note: Groups did not differ
Recovered
31
EFFORTFUL CONTROL AND NEGATIVE AFFECTIVITY
Figure 5
Effortful Control Score on CBQ
5
Change in Effortful Control Between Time Point 1 and Time
Point 2
4.9
4.8
4.7
4.6
Persistent-
4.5
Transitional
4.4
CWNS
4.3
Recovered
4.2
Before
After
Timepoint
Note: Groups did not differ from time point 1 to time point 2
Figure 6
Negative Affectivity Score on CBQ
Change in Negative Affectivity Between Time Point 1 and
Time Point 2
4.3
4.2
4.1
4
3.9
3.8
Persistent-
3.7
Transitional
3.6
CWNS
3.5
Recovered
3.4
3.3
Before
After
Timepoint
Note: Persistent and Transitional groups differed from time point 1 to time point 2
32
EFFORTFUL CONTROL AND NEGATIVE AFFECTIVITY
Table 1: Dimensions of Temperament Scales that Contribute to Each Higher Order Factor on the
Children’s Behavior Questionnaire
Extraversion/Surgency
Impulsivity
High Intensity Pleasure
Activity Level
Positive Anticipation
Negative Affectivity
Discomfort
Sadness
Fear
Anger/Frustration
Effortful Control
Low Intensity Pleasure
Inhibitory Control
Perceptual Sensitivity
Attentional Focusing
Smiling/Laughter
Soothability/Falling
Reactivity (loading
negatively)
Attentional Shifting
Shyness (loading
negatively)
Excitatory Control
Table 2: Group Means for Negative Affectivity and Effortful Control
NA time point 1 NA time point 2 EC time point 1
3.65
4.11
4.49*
Persistent
3.87
4.23
4.82
Transitional
3.64
3.96
4.93
CWNS
3.98
4.07
4.57*
Recovered
NOTE: * Significant at p < 05.
EC time point 2
4.46*
4.72
4.85
4.66
Table 3: Least Significant Difference Scores for Effortful Control at Time Point 1 and Time
Point 2
Groups
Persistent
Transitional
CWNS
Recovered
Persistent
1
0.089
0.003*
0.115
Transitional
0.113
1
0.335
0.689
CWNS
0.015*
0.56
1
0.097
Recovered
0.654
0.177
0.019*
1
NOTE: above diagonal is time point 1 and below diagonal is time point 2
* Significant at p < 05.