Acquisition of Linguistic and Cognitive Skills by ...

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JSLHR JSLHR,, Volume Volume 41, 41, 676–687, 676–687, June June 1998 1998

Acquisition of Linguistic and Cognitive Skills by Children With Cleft Palate Patricia A. Broen Monica C. Devers Shirley S. Doyle Jo McCauley Prouty Karlind T. Moller University of Minnesota Minneapolis

This study compared the early cognitive and linguistic development of young children with cleft palate (N = 28) to that of noncleft children (N = 29). Measures included the Mental scale of the Bayley Scales of Infant Development, the Minnesota Child Development Inventory, Mean Length of Utterance, and words acquired by 24 months. Children with cleft palate, although well within the normal range, performed significantly below the children in the control group on the Mental Scale of the Bayley Scales of Infant Development, some subscales of the Minnesota Child Development Inventory, and words acquired by 24 months. Differences observed in the cognitive development of children with and without cleft palate were verbal as opposed to nonverbal (i.e., linguistic in nature) and were related to hearing status at 12 months and velopharyngeal adequacy. KEY WORDS: cleft palate, language, cognition, hearing

O

ver the last 40 years a number of studies have examined the linguistic and cognitive development of children with cleft palate (Fox, Lynch, & Brookshire, 1978; Goodstein, 1961; Jocelyn, Penko, & Rode, 1996; Lamb, Wilson, & Leeper, 1973; Morris, 1962; Munson & May, 1955; Richman, 1980; Richman & Eliason, 1982; Spriestersbach, Darley, & Morris, 1958). Although measures were varied and results were mixed, the general finding was that the language skills of children with cleft palate were delayed or less well developed than those of their peers. Children with cleft palate performed more poorly on cognitive-intellectual measures than their peers. In addition, a number of studies (Lamb, Wilson, & Leeper, 1973; Richman, 1980; Richman & Eliason, 1982) suggest that the cognitive deficits that have been observed may be secondary to linguistic deficits. For example, some, but not all, studies found that children with cleft palate have lower scores on verbal IQ measures than on performance measures (Goodstein, 1961; Lamb, Wilson, & Leeper, 1973). These differences in the rate of linguistic and cognitive development of children with cleft palate are small, but fairly consistent, and not well understood. The observed deficits may be transient and related to difficulty with speech production. The finding of deficits in sentence length and other measures of expressive language that disappear by the time the child with cleft palate is 4 to 5 years of age is consistent with that interpretation (McWilliams, Morris, & Shelton, 1990; Shames & Rubin, 1979; Spriestersbach, Darley, & Morris, 1958). In other studies, however, early deficits in receptive and expressive language (Morris, 1962) appear to

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Broen et al.: Linguistic and Cognitive Skills and Cleft Palate

persist in children 8 years old and older. A number of factors have been cited as possible sources for these differences, including long hospital stays, hearing loss associated with middle ear effusion, poor subject selection, and poor speech intelligibility in the young child with cleft palate. Even the repeated exposure to pain related to surgery, experienced by some children with cleft palate, may interfere with their readiness to learn and thus be related to the observed delay (Savage, Neiman, & Reuter, 1994). There are factors that may influence the development of linguistic and cognitive skills in children with and without cleft palate. In her summary chapter, McCarthy (1954) described a number of such variables. For example, in some studies girls acquired language earlier than boys, children from lower socioeconomic families were slower to acquire language skills and performed more poorly on intellectual measures, and firstborn children tended to perform better on cognitive and linguistic measures than later-born children. In related studies, children with better-educated mothers scored higher on measures of intellectual functioning (Bee, Barnard, Eyres, Gray, Hammond, Spietz, Snyder, & Clark, 1982; Smith, Flick, Ferriss, & Sellman, 1972). Low birth weight and other types of perinatal stress have also been shown to be related to poor cognitive development (Smith et al., 1972). These are all possible sources for cognitive and linguistic differences, and, as Richman and Eliason (1982) and Lavigne and Willis (1990) point out, these factors have not been well controlled in studies of children with cleft palate. There are also factors specific to children with cleft palate that should be controlled or at least identified. Some studies have found that children with clefts of the secondary palate only (Goodstein, 1961) or children in lower-frequency cleft-type-by-sex groups (i.e., girls with cleft lip and palate and boys with cleft palate only) were more apt to have delayed language (Lamb, Wilson, & Leeper, 1973). Also, it is reasonable to anticipate that intelligibility would be related to language production in individuals with cleft palate. This has been found to be true in some studies of children (Faircloth & Faircloth, 1971) and of adults (Pannbacker, 1975). Congenital anomalies that include clefting may also include intellectual deficits, and children with such anomalies should be excluded from studies. Finally, children with cleft palate are prone to middle ear effusion and the mild-tomoderate hearing loss that may accompany it. These hearing losses may affect linguistic development (FrielPatti, Finitzo-Hieber, Conti, & Brown, 1982; Teele, Klein, & Rosner, 1984). The study presented here will re-examine some of these issues. Some of the variables cited as causes for delay no longer affect most children with cleft palate.

For example, children are seldom hospitalized for extended periods for repair of their palate. Hospital stays typically are now no longer than a day or two, and parents are encouraged to stay with their child. Furthermore, subject selection can be better controlled. Syndromes that include cleft palate are better recognized and delineated, and children with such syndromes are not, or need not be, included in the subject population. In the past, hearing data have often been retrospective, speculative, or unavailable. In the study presented here, information on hearing and middle-ear function was obtained prospectively and longitudinally throughout early childhood. This study will compare the cognitive and linguistic development of children with and without cleft palate during their first 30 months and describe the relationship among measures of language, cognitive ability, hearing, and velopharyngeal function. The following specific questions are addressed: 1.

Are the early cognitive and linguistic skills of children with cleft palate delayed relative to their noncleft peers?

2.

If there are differences in cognitive skills, are those differences language based?

3.

If there are differences in linguistic skills, are those differences related to hearing or to velopharyngeal function?

Method Subjects Two groups of children were followed: 28 children with cleft palate (18 boys and 10 girls) and 29 noncleft children (19 boys and 10 girls) (see Table 1). Among the children with cleft palate, 21 (17 boys and 4 girls) had complete clefts of the primary and secondary palate and 7 (1 boy and 6 girls) had clefts of the secondary palate only. On average, children were 13.3 months old (SD = 2.9) when their palate was repaired (range: 9 to 22 months); only 4 children were older than 15 months. Twelve of the children in the cleft group and 18 of the children in the noncleft group were first born. The socioeconomic status (SES) of the families of most of the children in both groups would receive Hollingshead (1975) ratings of 1 or 2—that is, professional or semiprofessional (see Table 1). The middle- to upper-middle-class nature of this sample is also reflected in the education of the mothers. All mothers were high-school graduates; the majority of the mothers had at least some education beyond high school, and more than 10% had some graduate school education (see Table 1). In part, this sample of more highly educated mothers occurred because these were the parents who were willing and able to participate in Journal of Speech, Language, and Hearing Research


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JSLHR, Volume 41, 676–687, June 1998

Table 1. Description of the cleft and noncleft groups. Cleft

No cleft

No.

%

No.

%

Gender Male Female

18 10

64.3 35.7

19 10

65.5 34.5

Cleft Type Primary & secondary Secondary only

21 7

75.0 25.0

SES 1&2 3, 4, & 5

20 8

71.4 28.6

22 7

75.9 24.1

Birth order First born Later born

12 16

42.9 57.1

18 11

62.1 37.9

6 10

21.4 35.7

1 8

3.4 27.6

9 3

32.1 10.7

15 5

51.7 17.2

Maternal education High school only Vocational school or some college Bachelor’s degree Graduate school

a longitudinal study lasting almost two years. Although the two groups were quite well matched on SES, there was a bias toward better-educated mothers in the noncleft group. For this reason, mother’s education was used as one of the covariates in the analysis of data, because maternal education has been shown to be one of the predictors of later child IQ (Bee et al., 1982). Birth order was also used as a covariate because more noncleft children were first born, and first-born children appear to acquire language skills at an earlier age (McCarthy, 1954). Children with cleft palate were identified through physicians and surgeons serving on cleft-palate teams and through parent support groups. Noncleft children were recruited from lists of parents who expressed an interest in participating in research at the time their child was born and from among the friends of the parents of the children with cleft palate. All children whose parents agreed to participate and who satisfied the following criteria were included in the study: (a) no identifiable syndrome, (b) weighed more than 5 pounds at birth and not considered premature (i.e., no more than 5 weeks preterm), (c) passed a developmental screening (Minnesota Infant Development Inventory, Ireton & Thwing, 1980), and (d) passed at least one hearing screening during the course of the study. Twenty-eight of the 33 children with cleft palate who were identified participated. Two children were unable to participate for personal reasons, 1 child was developmentally delayed and did not pass the initial cognitive screening, 1 child was 8 weeks premature, and one child never Journal of Speech, Language, and Hearing Research


passed a hearing screening. Twenty-nine of the 36 noncleft children identified were included in the study. Two children moved from the area, 2 were unable to complete the study for personal reasons, 2 exhibited behavior that made them untestable, and 1 child never passed a hearing screening. An attempt was made to match noncleft children to the children with cleft palate on gender and socioeconomic status, but attrition made exact matches impossible. For all children, English was the only language spoken in the home.

Procedures Children were seen in a university laboratory setting at 3-month intervals when they were between 9 and 30 months of age. Four children with cleft palate were identified late and did not begin the study until they were 12 months old. Each time a child was seen, hearing and middle-ear function were screened, and the child and parent were videorecorded as they played for 20 min in a sound-treated room equipped with childsized furniture and age-appropriate toys. Both parent and child wore transmitter microphones clipped 4 to 6 inches from their mouths. The videorecorder had highfidelity sound recording capabilities. Between 12 and 24 months, parents recorded each new word their child used. At 24 months the Mental scale of the Bayley Scales of Infant Development (BSID; Bayley, 1969) was administered, and at 30 months parents completed the Minnesota Child Development Inventory (MCDI; Ireton & Thwing, 1972). Videofluoroscopy was done for all of the children with cleft palate. Health records were obtained for all children from physicians, surgeons, cleft-palate teams, speech-language pathologists, and other health care providers.

Hearing Hearing was screened at .5, 1, and 2 kHz using warble tones in sound field and visual reinforcement. The exception to this procedure occurred at 30 months, when most children’s hearing was screened under earphones. Screening levels were 30 dB HL at 9 months, 25 dB HL at 12 months, and 20 dB HL thereafter. If a child failed a hearing screening, thresholds were obtained. These procedures were used because time constraints precluded obtaining thresholds for each child at each session. A Mean Warble Tone Score (MWTS) was calculated by averaging the child’s threshold performance (or the screening level) at the three frequencies tested. If it was not possible to obtain information at all three test frequencies, the pass-fail decision and the MWTS were based on the frequencies that were successfully tested. For children with cleft palate, decisions were based on three frequencies 92.3% of the time, two


frequencies 4.3% of the time, and one frequency 3.4% of the time. For the noncleft children, decisions were based on three frequencies 96.8% of the time, two frequencies 1.6% of the time, and one frequency 1.6% of the time. In some instances it was not possible to obtain a MWTS because children were uncooperative. Also, because 4 children with cleft palate did not begin the study until they were 12 months old, a 9-month MWTS was not available. Of the 456 possible hearing screenings, 17 (3.7%) were not obtained. All children retained in the study passed at least one hearing screening during the study, and hearing screening failures were assumed to reflect the effects of middle ear effusion. This assumption is supported by the observation that children who passed tympanometry in both ears rarely failed the screening (see Figure 1). For a more detailed account of hearing and middle-ear function in these children see Broen, Moller, Carlstrom, Doyle, Devers, and Keenan (1996).

679 Figure 1. Mean Warble Tone Score (MWTS) for children with cleft palate who passed tympanometry in no ears, one ear, or both ears. (Because of the procedures used, the best MWTS children could obtain was 30 dB at 9 months, 25 dB at 12 months, and 20 dB after 12 months). No child failed tympanometry in both ears at 30 months.

Velopharyngeal Function Although this study describes linguistic and cognitive development only through 30 months, medical and clinical records through at least 5 years were available. Velopharyngeal treatment decisions by age 5 were used as an indication of the adequacy of the velopharyngeal closure mechanism. It was assumed that by this time decisions could be made regarding the need for speech treatment or physical management of the velopharyngeal closure mechanism. Children who received no treatment beyond primary palatal surgery were assumed to have an adequate velopharyngeal mechanism, children who had secondary management of the velopharyngeal port were assumed to have inadequate velopharyngeal closure following primary palatal surgery, and children who received speech treatment were assumed to have a marginally adequate velopharyngeal mechanism or to accomplish velopharyngeal closure inconsistently for speech. If language learning is aided by the ability to produce intelligible, age-appropriate speech, the children with adequate velopharyngeal function following primary surgery should have an advantage. Lateral videofluoroscopic recordings of the velopharyngeal structures were obtained at 30 months as a part of the study. During this procedure, children were asked to repeat a list of words and phrases containing non-nasal consonants. Understandably, children varied in their ability to cooperate in the task. Using the recordings, judgments were made regarding the length and mobility of the soft palate and the extent and consistency of contact between the soft palate and the posterior pharyngeal wall. All judgments were made by one of the authors (KTM). Information obtained from the videofluoroscopic assessment was used to support

judgments of velopharyngeal adequacy that were based on treatment decisions. Velopharyngeal function, as reflected in (a) no treatment, (b) speech treatment, or (c) physical management, was used as an index of the adequacy of the velopharyngeal mechanism. Among the 28 children with cleft palate, 14 required no additional treatment beyond primary palatal surgery. The results of videofluoroscopy indicated that 12 of the 14 children were described as having goodto-extensive contact of the soft palate and the posterior pharyngeal wall. One child did not produce enough speech for a judgment to be made but appeared to have sufficient length for contact, and one child was judged as having inconsistent contact. Of the 14 children who required additional treatment, 8 received speech treatment but no physical management. These children were described as having short (4/8), short but sufficient (2/8), or sufficient (2/8) palatal length. Four were described as having inconsistent contact of the soft palate and the posterior pharyngeal wall, 2 as consistent contact, 1 could not be assessed, and 1 had contact that was described as fairly extensive. All of the 6 children who eventually required physical improvement of velopharyngeal closure (surgery in every case) were described as having short palates. Half demonstrated no pharyngeal wall contact; the other half had inconsistent, questionable, or occasional touch contact. Although a child could be referred for speech treatment for reasons other than concern with velopharyngeal closure (e.g., 2 children in the control group), information from videofluoroscopy suggested that the 8 children receiving speech treatment had less than an optimal Journal of Speech, Language, and Hearing Research


680 velopharyngeal mechanism, and the 6 children who had physical improvement of the velopharyngeal mechanism had videofluoroscopic findings consistent with inadequate closure, at least as seen in the lateral projection.

Measures Bayley Scales of Infant Development (BSID) The Mental scale of the BSID (Bayley, 1969) provides a well-standardized assessment of early mental and psychomotor development that spans the period from infancy to early childhood. It was administered at 24 months to all subjects by one of the authors (JP), who was trained in its administration. At 24 months of age children typically obtain a perfect score on the first 122 items of the Mental scale of the BSID. The next 41 items (i.e., items 123 through 163) are the items that discriminate among children at this age. These items were grouped as follows: 10 were considered expressive verbal items requiring the child to talk, 11 were considered receptive verbal items requiring the child to understand speech to complete the item, and 20 were nonverbal items that could be completed without understanding or using language. The expressive and receptive items were combined for an overall verbal score. The following are examples from each category: Expressive Verbal 124. What is this? (The child is shown a ball.) 136. Uses a sentence of at least 2 words. 150. Names the watch on the second picture. Receptive Verbal 126. Follows directions: “Put the doll on the chair.” 132. Points to three pictures. 158. Understands 2 prepositions: “Put the block on the cup.” “Put the block in the cup.” “Put the block under the cup.” Nonverbal 123. Puts pegs in peg board in 42 seconds. 143. Builds a tower of six cubes. 159. Completes blue board (round and square puzzle pieces) in 90 seconds. This division of items is consistent with the division used by Paul and Elwood (1991) and Paul and Jennings (1992). Because all of the children were 24 months old when this scale was administered, raw score performance will be reported.

Minnesota Child Development Inventory (MCDI) The Minnesota Child Development Inventory (Ireton & Thwing, 1972) was completed by parents before the Journal of Speech, Language, and Hearing Research



30-month session. This parent report measure has a General Development scale and seven subscales, including Expressive Language, Comprehension-Conceptual (a measure of receptive language), Gross Motor, Fine Motor, Personal-Social, Situation Comprehension, and Self-Help. At age 2, the language scales on the MCDI have been found to be correlated with and predictive of MLU and performance on the Sequenced Inventory of Communication Development (Tomblin, Shonrock, & Hardy, 1989). Both the BSID and the MCDI are cognitive-developmental measures, and both have language components, allowing any deficit observed on the cognitive measure to be related to linguistic ability. Again, because all children were 30 months old when this measure was completed, results will be reported in terms of raw scores.

Vocabulary The parent-report measure of vocabulary acquisition was obtained by asking parents to write down each new word their child used when their child was between 12 and 24 months of age. At the end of each 3-month period, parents brought their lists of words to the regular laboratory session. At the laboratory session, parents were questioned to determine the accuracy and completeness of their record.

Mean Length of Utterance (MLU) Sentence or utterance length is another measure of expressive language. One could assume that the longer the child’s sentences, the more complex the syntax. It has been suggested that MLU is a sensitive index of expressive syntactic abilities when MLU is greater than 1.0 and less than 4.0 (Brown, 1973; Miller, 1981; Templin, 1957). The MLUs in this study fall in that range. MLU was obtained for each child that was based on the first 50 intelligible utterances used by the child in the 30-month play session (Brown, 1973; Miller, 1981). Only one child failed to produce 50 intelligible utterances at 30 months. His MLU was based on 48 utterances. As a check on the reliability of the MLU measure, 8 tapes were scored by a second transcriber. Children from both groups were occasionally unintelligible. The transcribers scored the first 50 utterances that were intelligible to them, but what was intelligible to one transcriber was not always intelligible to the other transcriber. For this reason, the samples scored by the two transcribers were not identical. For the children with cleft palate, 77.8% (175/225) of the utterances scored by any transcriber were scored by both transcribers; for the noncleft children 80.2% (178/222) were scored by both transcribers. For utterances scored by both transcribers, the two transcribers were in exact agreement 82.9% of the time and agreed within one morpheme 97.1% of

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the time for children with cleft palate. For the noncleft children, exact agreement was 91.0%, and agreement within one morpheme occurred 98.3% of the time. The correlation between the MLUs obtained by the two transcribers was .99.

Data Analysis The performance of children with and without cleft palate was compared using an analysis of variance for each of the cognitive and linguistic measures to allow comparison with previous studies. A repeated-measures ANOVA was used to examine hearing and word acquisition. Because the groups differed on birth order and maternal education, these were used as covariates in the analysis of all cognitive and linguistic measures (but not hearing). Where group differences were found, a second set of analyses was done which added hearing as a covariate, and a third set was done which added velopharyngeal function as a covariate.

Results Hearing Because of the screening procedure used, no child could obtain a MWTS better than 30 dB at 9 months, 25 dB at 12 months, or 20 dB after 12 months. A modified MWTS was calculated by subtracting the screening level from the child’s score (see Figure 2). This difference score eliminated the effects of changes in screening level with age. The hearing of the children with cleft palate, as reflected in the modified MWTS, was significantly poorer than that of the noncleft children [F(1, 41) = 5.66, p = .022]. Age [F(7, 287) = 7.61, p Figure 2. The difference between Mean Warble Tone Scores (MWTS) and the screening level for children with cleft palate (circles) and without cleft palate (squares).

< .001] and the cleft status-by-age interaction [F(7, 287) = 2.80, p = .008] were also significant. Even with the effects of higher screening levels for younger children removed, younger children had higher MWTS. The interaction reflects the fact that children with cleft palate had higher MWTS than the noncleft children (i.e., poorer hearing) at 9, 12, and 15 months. T tests with Bonferoni corrections indicated that these differences were all significant (.01). Because MWTS are missing for 8 children with cleft palate at 9 months and 2 noncleft children at 15 months, the 12-month MWTS was used as an index of the children’s early hearing in the analysis of the data.

Cognitive-Developmental Measures The Mental Scale of the Bayley Scales of Infant Development The mean raw score for children with cleft palate was 148.7 (SD = 7.2); the mean raw score for noncleft children was 153.3 (SD = 4.9) (see Table 2). Although the difference between these two means was statistically significant [F(1, 53) = 6.61, p = .01], the children with cleft palate were not delayed relative to the norming population. The mean score reported in the normative data for 24month-old children was 144.6 (SD = 8.5). Therefore, as a group, the children with cleft palate in this study were slightly above the mean for their age, and the noncleft children were a standard deviation above the mean. When the performance of the two groups was compared on verbal and nonverbal items, the children with cleft palate scored significantly lower on the verbal, but not on the nonverbal items (see Table 2). The mean verbal score for the children with cleft palate was 13.0 (SD = 4.9) on the 21 verbal items; the mean verbal score for the noncleft children was 16.3 (SD = 3.6). The difference was significant [F(1, 53) = 6.37, p = .01] (see Table 2). This reflected a significant difference in performance on the receptive [F(1, 53) = 6.37, p = .01] but not the expressive [F(1, 53) = 3.02, p = .09] items. The mean nonverbal score for children with cleft palate was 14.1, and for noncleft children the mean score was 15.3 [F(1, 53) = 3.32, p = .07]. Although it has been suggested that lower frequency sex-by-cleft type groups (i.e., males with clefts of the secondary palate only or females with complete clefts) are more apt to be delayed in the development of language skills (Lamb, Wilson, & Leeper, 1973), they did not account for the differences observed in this study. The 5 children in the lower-frequency sex-by-cleft type group (1 boy with a cleft of the secondary palate only and 4 girls with complete cleft of the primary and secondary palate) scored higher on the BSID and on each of the subscales as defined in this study (see Table 3). There was no indication Journal of Speech, Language, and Hearing Research


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Table 2. Performance of children with and without cleft palate on the verbal and nonverbal components of the Mental Scale of the Bayley Scales of Infant Development. The number of items in each subsection appears in parentheses. Birth order and mother’s education were covariates in this analysis. Measure

Cleft

SD

No cleft

SD

Total score Verbal (21) Expressive (10) Receptive (11) Nonverbal (20)

148.7 13.0 6.3 6.7 14.1

7.2 4.9 3.5 2.2 3.2

153.3 16.3 8.0 8.3 15.3

4.9 3.6 2.9 1.6 2.3

F

Probability

6.61 6.37 3.02 7.50 3.32

.01 .01 .09 .008 .07

Note. The mean score for 24-month-old children as reported in the norms is 144.6 (SD = 8.5).

Table 3. A comparison of the performance of children in low-frequency sex-by-cleft-type groups and children with isolated cleft palate with other children with cleft palate on the Bayley Scales of Infant Development. Bayley Scales of Infant Development Total Group Low frequency Other cleft Cleft of the primary palate only Cleft of the primary and secondary palate

Expressive

Receptive

Nonverbal

n

M

SD

M

SD

M

SD

M

SD

5 23

151.4 148.1

5.6 7.5

7.2 6.1

2.6 3.7

7.6 6.5

1.7 2.3

15.0 13.9

3.2 3.2

7

150.6

8.6

8.4

1.9

7.4

2.2

13.3

4.7

21

148.1

6.8

that the difference between the children with and without cleft palate was the result of poorer performance by the lower-frequency sex-by-cleft type groups. In this study both children with cleft of the primary and secondary palate and children with cleft of the secondary palate only have been included, but these are two separate disorders (Charrow, 1990). Goodstein (1961) found lower mean IQ scores in children with cleft of the secondary palate only than in children with cleft of the primary and secondary palate. There were 7 children, 1 boy and 6 girls, with cleft of the secondary palate only. Again, there was no evidence in our sample that children with isolated cleft of the secondary palate accounted for differences between the cleft and the noncleft groups. Their mean Bayley score and scores on all of the subscales except the nonverbal scale were higher than those of children with cleft of the primary and secondary palate (see Table 3). The mean score of the children with a cleft of the secondary palate only was slightly lower on the nonverbal items, but the difference between the groups was small and not significant [t(26) = .75, p =.46].

Minnesota Child Development Inventory The mean performance of both groups of children on the MCDI was at or near the mean for 30-month-old Journal of Speech, Language, and Hearing Research


5.6

3.7

6.5

2.2

14.3

2.6

children. Although there was a tendency for the children with clefts to perform more poorly than the noncleft children on the General scale of the MCDI (see Table 4), this difference was not significant. When performance on individual subscales was compared, however, the children with clefts performed as well or better than the noncleft children on five of the seven subscales. It was only on the language subscales, Expressive Language [F(1, 53) = 4.37, p = .04] and Comprehension–Conceptual [F(1, 53) = 3.93, p = .05], that the performance of the children with clefts was significantly poorer than the noncleft children.

Language Measures Rate of Vocabulary Acquisition The children with cleft palate acquired words more slowly than the noncleft children (see Figure 3). As a group, they appear to be about 3 months slower. The difference between the parent-reported vocabulary of the cleft and noncleft groups was not significant [F(1, 53) = 3.74, p = .06], but age [F(4, 220) = 111.37, p < .001] and the interaction of cleft-by-age [F(4, 220) = 4.30, p = .002] were. One would expect that age would be a significant factor because, in all children, vocabulary increases in size as they become older. The cleft-by-age interaction

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Table 4. Raw scores obtained on the Minnesota Child Development Inventory at 30 months by children with and without cleft palate. Mother’s education and birth order were covariates. Cleft

No cleft

M

SD

M

SD

F

p

General

84.29

10.55

88.72

8.77

1.59

.21

Comprehension-Conceptual Expressive Language Gross Motor Fine Motor Situation Comprehension Personal-Social Self Help

32.04 43.46 27.39 30.32 30.75 26.46 21.25

7.97 5.84 1.87 1.93 3.97 3.19 4.39

37.45 47.31 26.41 30.83 30.52 26.31 20.38

7.33 5.01 2.03 1.75 4.12 3.47 3.40

3.93 4.37 4.47