"Twin language": a risk factor for language impairment?

Speech processing performance of Hungarian-speaking twins and singletons

Studying speech processing in twins versus their singleton peers provides opportunities to study both genetic and environmental effects on how children acquire these aspects of their speech and - by extension - their phonological systems. Our study focused on speech processing in typically developing Hungarian-speaking twins and their singleton peers between 5 and 9 years of age. Participants included 384 monolingual Hungarian-speaking children (192 twins, and 192 singletons). Data from four tasks - repetition of synthesised monosyllables, nonsense words, well-formed noisy sentences, and well-formed phonologically complex sentences - were analysed. There was a main effect for birth status, and singletons outperformed their twin peers on the majority of the speech processing tasks. Age and task also had effects on the performance of the participants, and there was a three-way task by age by twin versus singleton status indicating that the speech processing performance of twins versus singletons is interdependent with the type of task and age. Our results also indicate that monolingual Hungarian-speaking twins may be at higher risk for developmental speech delays relative to their singleton peers.

Effect of sex and dyad composition on speech and gesture development of singleton and twin children

Children's early vocabulary shows sex differences - with boys having smaller vocabularies than age-comparable girls - a pattern that becomes evident in both singletons and twins. Twins also use fewer words than their singleton peers. However, we know relatively less about sex differences in early gesturing in singletons or twins, and also how singletons and twins might differ in their early gesture use. We examine the patterns of speech and gesture production of singleton and twin children, ages 0;10-to-3;4, during structured parent-child play. Boys and girls - singleton or twin - were similar in speech and gesture production, but singletons used a greater amount and diversity of speech and gestures than twins. There was no effect of twin dyad type (boy-boy, girl-girl, boy-girl) on either speech or gesture production. These results confirm earlier research showing close integration between gesture and speech in singletons in early language development, and further extend these patterns to twin children.

Longitudinal Study of Expressive Language and Speech of Twins at 3 and 5 Years: Outgrowing a Twinning Effect

Purpose This study examines the expressive language and speech of twins, relative to singletons, at 3 and 5 years, with the aim of determining if a twinning effect occurs during this developmental period. The possibility of twins outgrowing a twinning effect was investigated. Method A weighted population-based sample of 185 twins and 1,309 closely spaced singletons who participated in the Growing Up in Ireland study was analyzed. Their development was compared using a standardized expressive vocabulary assessment and parent interview at 3 and 5 years as well as teacher reports at 5 years. Causal steps mediation analyses were subsequently conducted to determine if gestation and birth weight mediated twin-singleton differences in expressive vocabulary development. Results Twins' expressive vocabulary scores were slightly lower than those of singletons at 3 years, but there was no significant difference at 5 years. More parents of twins reported "a little" concern about their child's expressive language and speech skills at 3 years, although there was no significant twin-singleton difference 2 years later. Teachers' ratings of twins' and singletons' expressive language and speech skills at 5 years were comparable. Shorter gestations and lower birth weights mediated twins' lower expressive vocabulary scores at 3 years. Conclusions A very small twinning effect on expressive vocabulary development exists at 3 years and is outgrown by 5 years. Twins born after shorter gestations or at a lower birth weight are at an increased risk of having less developed expressive vocabulary skills at 3 years.

The relationship between twin language, twins' close ties, and social competence

This study investigated the relationship between twin language, twins' close ties, and social competence in a prospective longitudinal study. We hypothesized that twins whose tie is close would be more likely to develop a twin language, and these twins would be less likely to develop social competence. In addition, we hypothesize that some environmental factors, such as having an older sibling, preschool attendance, zygosity, and sex are also related to twin language, twins' close ties, and social competence. At baseline in 1999 a mailed questionnaire survey was conducted, and a follow-up questionnaire was distributed in 2004 among 958 mothers. As a result, 516 respondents returned the questionnaire (53.9%). In this study, we used 261 twin pairs aged from 6 to 12 years (school-age children) for analysis, excluding those with missing values. In the present study, we found that zygosity and sex were associated with twins' close ties. Having an older sibling and preschool attendance did not affect the twins' close tie, twin language, or social competence. One of the most important findings was that social competence was not affected directly by twins' close tie, but was affected when a twin language was found.

Motor development of Japanese twins in childhood as reported by mothers

OBJECTIVE

Twins tend to lag behind singletons in their motor development, though the causes of this appear to be complicated and are not yet fully understood. The present study was performed to clarify the factors associated with the motor development of twins.

METHODS

The twins in the first group consisted of school applicants, including 1131 twin pairs, and the second group consisted of children of members of several maternal associations, and included 951 pairs. All data were gathered by questionnaire survey, and six gross-motor development milestones were analyzed in individuals or pairs.

RESULTS

Relative to general population norms in Japan, twins tended to be delayed in reaching several motor development milestones. Stepwise regression analysis showed that of all the variables measured, gestational age was the most influential on all six milestones. Birthweight was also influential on most milestones. Other factors affecting motor development milestones were parity for 'sitting without support,' 'pulling up to a standing position,' and 'walking without support,' and zygosity for 'walking without support.' In these cases, longer gestational age, heavier birthweighf, primiparity, and dizygosity showed a tendency toward earlier attainment of development. Motor development within pairs was more similar in monozygotic pairs compared with dizygotic pairs regarding each item, suggesting genetic contributions.

CONCLUSION

The results of the present study showed specific and nonspecific factors that affect motor development of twins. These findings should prove useful in understanding the motor development of twin children and help clinicians to refine maternal and child health care for multiple-birth children.

Relationship Between Parents' Report Rate of Twin Language and Factors Related to Linguistic Development: Older Sibling, Nonverbal Play and Preschool Attendance

The definition and nature of twin language has been a focus of recent studies concerned with the phenomenon. There has been a call for a tighter definition and understanding of the meaning of twin language (Thorpe et al., 2001). This article sought to identify social factors associated with the parent report of twin language and thus provide further understanding of the phenomenon. Data from 583 mothers of twins aged 25 to 59 months were analyzed using multiple logistic regression. Factors included in the modeling of parent-report twin language included social experience factors such as presence of siblings, attendance at preschool education and reports of nonverbal play. It was found that twin pairs who didn't have an older sibling, who showed frequent nonverbal play and who didn't attend preschool were more likely to have a twin language. Moreover, in the group not having an older sibling, the influence of whether twins attended preschool or not was strong and the odds ratio was 0.589 (95% confidence intervals 0.360–0.963). The findings suggest that social experience factors are important predictors of the parent reporting of twin language.

Attention interchanges at story-time: a case study from a deaf and hearing twin pair acquiring Swedish sign language in their deaf family

This case study longitudinally analyzes and describes the changes of attentional expressions in interchanges between a pair of fraternal twins, 1 deaf and 1 hearing, from the age of 10-40 months, and their Deaf family members. The video-observed attentional expressions of initiating and reestablishing interchange were grouped in 5 functional categories: "getting," "directing," "maintaining," "redirecting," and "checking" attention. Changes appear to be associated with development during the twins' ages of 10-13, 15-24, and 28-40 months, including the use of vision in communication. Although there are similarities in the changes of each twin's communicative initiations, there are also differences based on hearing status, personality, and use of modality. This is evident in the ways in which each twin's individual attention interchanges unfold over time; it is also connected with the parents' negotiating attention and arranging "seating positions" with them. Implications and findings for special educational purposes are discussed.

An alternating treatment comparison of minimal and maximal opposition sound selection in Turkish phonological disorders

A single-subject alternating treatment design in combination with a staggered multiple baseline model across subjects was implemented with two 6:0 year-old girls, monozygotic twins, who were referred to a university clinic for evaluation and treatment. The treatment programme was structured according to variants of minimal pair contrast treatment in which the target sounds and their oppositions were selected according to either minimal or maximal opposition (including major-class differences) contrast treatments to evaluate which of the sound selection strategy would result in better learning. Independent variables were the minimal and maximal opposition conditions; dependent variables were the target phonemes treated. Consistent with the literature, maximal opposition treatment resulted in significantly greater changes in the sound systems of the twins than minimal opposition treatment.

Sobre o desenvolvimento da linguagem de gêmeos monozigóticos

OBJETIVO: analisar o relato dos familiares sobre o desenvolvimento dos filhos gêmeos, desde o momento da descoberta de uma gestação gemelar monozigótica, à procura de indícios dos fatores interacionais e sua relação com a linguagem. MÉTODOS: trata-se de um estudo naturalista observacional e os dados foram coletados por meio de entrevistas semi-estruturadas realizadas com nove famílias de gêmeos monozigóticos, durante 30 meses. A análise dos dados orientou-se pelo paradigma indiciário e pelos preceitos da perspectiva histórico-cultural. RESULTADOS: sete famílias relataram um desenvolvimento diferenciado de linguagem, mas não foi ressaltado de maneira tão relevante a ponto de causar preocupação na família. CONCLUSÃO: no discurso das famílias, a gemelaridade pode trazer implícita a idéia de que o desenvolvimento das crianças não segue o esperado, já que a própria condição de ser gêmeo não é esperada.

Aspectos fonoaudiológicos e pediátricos na linguagem de gêmeos monozigóticos

OBJETIVO: Observar o discurso familiar a respeito da gemelaridade, por meio de categorias inseridas nas práticas sociais, buscando subsidiar e delinear a contribuição do fonoaudiólogo e do pediatra no desenvolvimento de linguagem dos gêmeos monozigóticos. MÉTODOS: O trabalho apóia-se no método qualitativo de pesquisa e a análise dos dados foi realizada segundo a perspectiva histórico-cultural e o paradigma de natureza indiciária. Em 30 meses, foram realizadas oito entrevistas semi-estruturadas seqüenciais, iniciadas à revelação da gestação gemelar e continuadas em intervalos aproximados de três meses até cerca de dois anos de vida dos gêmeos, com dez famílias que tinham em sua composição direta um par de gêmeos idênticos. RESULTADOS: Sete categorias emergiram nos relatos obtidos com os familiares - a descoberta da gemelaridade, a escolha de nomes, o vestuário, a interação, a rotina, a linguagem e a identidade. CONCLUSÕES: Os depoimentos, práticas, valores e pressupostos estão relacionados com o desenvolvimento destas crianças e apontam que essas famílias precisam de um acompanhamento diferenciado e específico, desde o momento gestacional.

Desenvolvimento do sistema fonológico de gêmeos monozigóticos com desvio fonológico: correlação a fatores genéticos e ambientais

OBJETIVO: descrever os sistemas fonológicos de irmãos gêmeos monozigóticos com desvio fonológico e analisar a evolução da terapia fonoaudiológica após a aplicação do Modelo de Oposições Máximas Modificado a fim de investigar a influência de fatores genéticos e ambientais na instalação e manutenção das desordens fonológicas. MÉTODOS: foram comparadas as avaliações fonológicas iniciais, os sons-alvo utilizados no planejamento terapêutico, e as avaliações fonológicas finais de cada ano de tratamento de dois sujeitos gêmeos monozigóticos do gênero masculino, com idade de seis anos e cinco meses no início da pesquisa, e com diagnóstico de desvio fonológico. Os meninos receberam atendimento de agosto de 2002 a dezembro de 2004 por meio do Modelo de Oposições Máximas Modificado. Todos os materiais foram coletados do banco de dados de um projeto desenvolvido no curso do Fonoaudiologia da Universidade Federal de Santa Maria. RESULTADOS: grandes semelhanças foram verificadas nos sistemas fonológicos dos dois sujeitos no início, durante a evolução terapêutica e no final da terapia fonológica, apesar não terem sido utilizados necessariamente os mesmos sons-alvo no tratamento. Os meninos adquiriram os sons ausentes e parcialmente adquiridos, apresentando generalização nas diversas situações possíveis, o que comprovou a eficácia do modelo terapêutico aplicado. CONCLUSÃO: a influência genética interfere na instalação e manutenção das desordens fonológicas, porém os fatores ambientais não podem ser descartados.

Twin children's language development

Scientific studies have consistently reported that, in group analyses, twin children have higher rates of language delay when compared with single-born children. This paper reviews the evidence on twin language by addressing five key questions:The paper concludes that language delay in twins when compared with singletons is mild yet prevalent, particularly in males and is most likely a result of experience of poorer quality of language environment compared to single born children. Occurrence of "private" or "twin" language is rare and not an explanation for the findings of generalised language delay among twins. Given that language delay in twins relates to social-language experience, appropriate intervention and remediation of language delay should focus on providing a more stimulating language environment both within and outside the home. It is recommended that future research examine, longitudinally, the developmental course and consequences of language delay in twin children and trial interventions designed to improve their language experiences.

Interdisciplinary and prospective studies necessary to increase insight into developmental language disorders

The study of developmental language disorders is discussed from an interdisciplinary perspective. It is argued that retrospective studies have provided valuable information on developmental language disorders that needs to be integrated into a theoretical model capable of capturing the basic mechanisms of language development.

CONCLUSION

It is concluded that interdisciplinary and prospective studies and theoretical work are necessary to increase insight into developmental language disorders.

Genetic, environmental, and gender effects on individual differences in toddler expressive language

In this article, the authors examined the genetic and environmental factors influencing expressive language development in a sample of 386 toddler twin pairs participating in the Wisconsin Twin Project. Expressive language was assessed using 2 measures from the MacArthur Communicative Development Inventories-Short Form: Total Vocabulary and Two-Word Combination Use (L. Fenson et al., 2000). A sex-limitation structural equation model estimated the contribution of genetics, shared environment, and nonshared environment to individual variation. For vocabulary, heritability was higher for boys than for girls (20% vs. 8%). For word combination use, heritability was higher for girls (28% vs. 10%). However, the majority of individual variation in both boys and girls could be attributed to shared environment (54%-78%).

Factors affecting the appearance of 'twin language': An original language naturally developing within twin pairs

OBJECTIVES

The appearance of 'twin language' has been highlighted as a reason for delayed language development in twins. 'Twin language' is a unique language understandable only within the pair, and not by their mother or others. The purpose of this study was to examine and clarify the factors affecting the appearance of 'twin language'.

METHODS

A mailed questionnaires survey was conducted in 2733 mothers of twins. Of them, 1395 mothers returned the questionnaires. The core questionnaire asked for data on birth weight, age at first spoken word, whether the twins were as alike as two peas in a pod, household members and non-verbal play. Logistic regression analysis was used in this study.

RESULTS

Out of the 1395 pairs included in this analysis, 598 pairs (42.9%) showed the appearance of a 'twin language'. When the 598 pairs were divided by whether the twin pair was exactly alike or not, there were 112 opposite sex pairs, 105 not-alike male pairs, 106 not-alike female pairs, 129 exactly alike male pairs and 140 exactly alike female pairs. Namely, 38.4% of the opposite sex pairs, 40.4% of the not-alike male pairs, 39.3% of the not-alike female pairs, 47.6% of the exactly alike male pairs and 48.4% in the exactly alike female pairs had a twin language. By multivariate logistic regression analysis controlling for twins' age, it was found that 'twin language' was significantly more frequent in exactly alike twin pairs, pairs with non-verbal play, and pairs with fewer older siblings.

CONCLUSIONS

These findings suggest that three factors (whether the twin pair is exactly alike or not, older siblings, non-verbal play) affect the appearance of 'twin language'.

Twins as a natural experiment to study the causes of mild language delay: I: Design; twin-singleton differences in language, and obstetric risks

BACKGROUND

Twins tend to lag behind singletons in their language development, but the causes were unknown. The possibilities suggested include obstetric complications, twin-specific features, and postnatal differences in family interaction. The present study was designed to pit these alternatives against one another as possible causal influences.

METHOD

The Avon Longitudinal Study of Parents and Children (ALSPAC) was used to identify the 116 twin pairs (of whom 96 participated) and 114 pairs of singletons (of whom 98 participated) whose ages were no more than 30 months apart. The McArthur Communicative Development Inventory was completed at 20 months, and the Pre-School Language Scales (PLS-3), and the McCarthy Scales of Children's Abilities at 36 months. Obstetric and perinatal complications were assessed on the basis of detailed systematic parental reports, together with a systematic coded abstraction of all medical records dealing with pregnancy and the neonatal period. Family background details were assessed from parental reports, and the primary carer's verbal functioning was assessed by the Mill Hill Vocabulary Scale. Congenital anomalies were assessed using the method of Waldrop and Halverson.

RESULTS

The language of twins was 1.7 months below that of singletons at 20 months and 3.1 months at 3 years. The verbal cognitive score of twins was about half a standard deviation lower than that of singletons. The twin-singleton differences in language level were found tobe unassociated with obstetric/perinatal features as assessed from both parental reports and medical records, to birthweight or gestation, to birthweight discrepancy within the twin pair, or to congenital anomalies.

CONCLUSION

It is concluded that obstetric/perinatal features do not account for the slower language development in twins as compared with singletons, within a sample born after at least 33 weeks gestation.