Didactic adjustments in fathers' and mothers' speech to their 3-month-old infants

Vocal dialogues of 3-month-old infants with their mothers and fathers were recorded during dyadic interactions in the laboratory. Six-minute speech samples were analyzed for syntacticlexical and temporal-melodic features. Both parents adopted strikingly similar speech registers. Segmentation, reduction in syntactic complexity, repetitiveness, and slow tempo were more marked than reported for parental speech to children above 1 year. However, rather than providing proper linguistic models, parents utilized simplified patterns of expressive melodic contours as the most salient units of speech. This tendency is interpretable as age-specific adjustment to infants' integrative capacities. Structural similarities between maternal and paternal baby talk by far outweighed a few quantitative differences. The intuitive nature of recourse to basic nonverbal properties of vocal communication, together with universality across sex, favors the assumption that baby talk is a part of species-specific didactic support to infant communicative development.     

Distinct Facial Characteristics Differentiate Communicative Intent of Infant‐Directed Speech

Adults and infants can differentiate communicative messages using the nonlinguistic acoustic properties of infant‐directed (ID) speech. Although the distinct prosodic properties of ID speech have been explored extensively, it is currently unknown whether the visual properties of the face during ID speech similarly convey communicative intent and thus represent an additional source of social information for infants during early interactions. To examine whether the dynamic facial movement associated with ID speech confers affective information independent of the acoustic signal, adults' differentiation of the visual properties of speakers' communicative messages was examined in two experiments in which the adults rated silent videos of approving and comforting ID and neutral adult‐directed speech. In Experiment 1, adults differentiated the facial speech groups on ratings of the intended recipient and the speaker's message. In Experiment 2, an original coding scale identified facial characteristics of the speakers. Discriminant correspondence analysis revealed two factors differentiating the facial speech groups on various characteristics. Implications for perception of ID facial movements in relation to speakers' communicative intent are discussed for both typically and atypically developing infants. Copyright © 2012 John Wiley & Sons, Ltd.     

Maternal speech style with prelinguistic twin infants

The mother–infant communicative speech of a group of mothers of 4‐month‐old first‐born twin infants was compared to the speech of a group of mothers of first‐born singleton infants. Maternal groups were matched on age, education level, mother–infant attachment status and infant gender, and maternal depression was assessed as a control variable. Maternal speech was coded for focus, content, complexity and syntax of mothers' utterances. The findings of earlier studies with toddler age twins, that maternal speech style was more directive and less infant‐focused, were replicated in this prelinguistic period of infancy. Compared to mothers of singletons, mothers of twins used less infant‐focused speech, were less responsive to their infants' cues, and attributed less agency to their infants. Mothers of twins also used fewer questions and requests but did not differ from mothers of singletons in their use of negatives and imperatives. These early differences in the language learning environments of twin and singleton infants may be due to the reduced opportunities that mothers of twins have to establish dyadic communicative routines with their infants and to familiarize themselves with their infants as interactive partners, and may have implications for the early language development of twins. Copyright © 2002 John Wiley & Sons, Ltd.     

Frontal brain electrical activity (EEG) and heart rate in response to affective infant-directed (ID) speech in 9-month-old infants

Many studies have shown that infants prefer infant-directed (ID) speech to adult-directed (AD) speech. ID speech functions to aid language learning, obtain and/or maintain an infant's attention, and create emotional communication between the infant and caregiver. We examined psychophysiological responses to ID speech that varied in affective content (i.e., love/comfort, surprise, fear) in a group of typically developing 9-month-old infants. Regional EEG and heart rate were collected continuously during stimulus presentation. We found the pattern of overall frontal EEG power was linearly related to affective intensity of the ID speech, such that EEG power was greatest in response to fear, than surprise than love/comfort; this linear pattern was specific to the frontal region. We also noted that heart rate decelerated to ID speech independent of affective content. As well, infants who were reported by their mothers as temperamentally distressed tended to exhibit greater relative right frontal EEG activity during baseline and in response to affective ID speech, consistent with previous work with visual stimuli and extending it to the auditory modality. Findings are discussed in terms of how increases in frontal EEG power in response to different affective intensity may reflect the cognitive aspects of emotional processing across sensory domains in infancy.     

Infant vocal development during the first 6 months: speech quality and melodic complexity

The early development of infant non‐distress vocalizations was investigated in this study. Thirteen infants, from 4 to 24 weeks of age, and their mothers were observed weekly in a face‐to‐face interaction situation. The speech quality (syllabic versus vocalic) and melodic complexity (simple versus complex) of infant vocalizations were coded independently. Based on speech quality and melodic complexity, four types of infant non‐distress vocalizations were categorized: simple and complex syllabic (speech‐like) vocalizations as well as simple and complex vocalic (non‐speech‐like) vocalizations. Results showed that complex syllabic sounds were of longer duration and complex vocalic sounds were less frequent than the other types of vocalizations. Curvilinear developmental trends were found in the rate of simple vocalic sounds and in the mean duration of complex syllabic sounds. Furthermore, before 4 months of age, vocalic sounds were more likely to be associated with simple melodic contours, after which syllabic sounds were more likely to be associated with complex melodic contours. A dynamic systems perspective on the early development of infant vocalization is discussed. Copyright © 2000 John Wiley & Sons, Ltd.     

Infants of depressed mothers,although competent learners,fail to learn in response to their own mothers' infant-directed speech

Depressed mothers use less of the exaggerated prosody that is typical of infant-directed (ID) speech than do nondepressed mothers. We investigated the consequences of this reduced perceptual salience in ID speech for infant learning. Infants of nondepressed mothers readily learned that their mothers' speech signaled a face, whereas infants of depressed mothers failed to learn that their mothers' speech signaled the face. Infants of depressed mothers did, however, show strong learning in response to speech produced by an unfamiliar nondepressed mother. These outcomes indicate that the reduced perceptual salience of depressed mothers' ID speech could lead to deficient learning in otherwise competent learners.     

Mothers speak differently to infants at‐risk for dyslexia

Dyslexia is a neurodevelopmental disorder manifested in deficits in reading and spelling skills that is consistently associated with difficulties in phonological processing. Dyslexia is genetically transmitted, but its manifestation in a particular individual is thought to depend on the interaction of epigenetic and environmental factors. We adopt a novel interactional perspective on early linguistic environment and dyslexia by simultaneously studying two pre‐existing factors, one maternal and one infant, that may contribute to these interactions; and two behaviours, one maternal and one infant, to index the effect of these factors. The maternal factor is whether mothers are themselves dyslexic or not (with/without dyslexia) and the infant factor is whether infants are at‐/not‐at family risk for dyslexia (due to their mother or father being dyslexic). The maternal behaviour is mothers’ infant‐directed speech (IDS), which typically involves vowel hyperarticulation, thought to benefit speech perception and language acquisition. The infant behaviour is auditory perception measured by infant sensitivity to amplitude envelope rise time, which has been found to be reduced in dyslexic children. Here, at‐risk infants showed significantly poorer acoustic sensitivity than not‐at‐risk infants and mothers only hyperarticulated vowels to infants who were not at‐risk for dyslexia. Mothers’ own dyslexia status had no effect on IDS quality. Parental speech input is thus affected by infant risk status, with likely consequences for later linguistic development.     

旋律语调疗法及其对失语症的临床应用

失语症是当今人类面临的一个重要的健康问题。旋律语调疗法被认为是治疗失语症的有效手段之一。传统旋律语调疗法强调严格的程序和材料,改编版本则依据患者情况进行调整,二者均能提高失语症者的自发言语产生、言语复述以及命名等能力。研究还表明,旋律语调疗法不仅能提高失语症者相关脑区的激活水平,而且也能通过影响失语症者的相关神经结构改善其言语功能。未来研究需要进一步确定该疗法的干预机制及其对汉语失语症的适用性。     

Observer Influences on Fathers and Mothers: An Experimental Manipulation of the Structure and Function of Parent – Infant Conversation

From studies over the past 20 years four contrasting hypotheses can be made about the nature of parent–infant communication: (1) mothers and fathers display similar skills to their infants and do not exert a differential influence on their development; (2) fathers are less sympathetic to their infants' level of development and therefore inadvertently stretch the child's development more than mothers; (3) both parents differentially socialize their sons' and daughters' early communicative skills; (4) any apparent differences between parents reflect their expectations about being observed. To examine these hypotheses together, this experiment records the communication of 10 mother–infant and 10 father–infant dyads in two conditions: when an observer was present or absent. The analysis revealed two patterns. Firstly, in keeping with most research on parent–child communication, mothers and fathers both simplified their speech to their infants in similar ways. Secondly, both the structure and function of parental communication showed differences between the two conditions and many of these differences were moderated by interactions between condition and sex of parent or child. The data thus provide more support for the first and fourth hypotheses cited above. It is suggested that analyses of parent–infant interaction should move away from simple assumptions about parental ‘influences’ upon children's development to consider the subtleties of different parental styles in different settings.     

ACOUSTIC ANALYSIS OF ORAL PRODUCTIONS OF INFANTS LATER DIAGNOSED WITH AUTISM AND THEIR MOTHER

Research on early signs of autism in social interactions often focuses on infants’ motor behaviors; few studies have focused on speech characteristics. This study examines infant‐directed speech of mothers of infants later diagnosed with autism (LDA; n = 12) or of typically developing infants (TD; n = 11) as well as infants’ productions (13 LDA, 13 TD). Since LDA infants appear to behave differently in the first months of life, it can affect the functioning of dyadic interactions, especially the first vocal productions, sensitive to expressiveness and emotions sharing. We assumed that in the first 6 months of life, prosodic characteristics (mean duration, mean pitch, and intonative contour types) will be different in dyads with autism. We extracted infants’ and mothers’ vocal productions from family home movies and analyzed the mean duration and pitch as well as the pitch contours in interactive episodes. Results show that mothers of LDA infants use relatively shorter productions as compared to mothers talking to TD infants. LDA infants’ productions are not different in duration or pitch, but they use less complex modulated productions (i.e., those with more than two melodic modulations) than do TD. Further studies should focus on developmental profiles in the first year, analyzing prosody monthly.     

Maternal mind-mindedness over infants’ first three months

Maternal mind-mindedness refers to mothers’ ability to reflect upon their infants’ mental states and respond appropriately. The present study assessed mind-mindedness longitudinally from the newborn period to the infant age of three months. The study is the first to assess maternal mind-mindedness in the infant’s early life prior to three months (one week, one month, two months, three months). To measure maternal mind-mindedness, mothers’ speech to their infants is coded for mental state comments about the infants’ thoughts, desires, and emotions. Appropriate mind-minded comments are judged to accurately reflect the infants’ mental states; non-attuned mind-minded comments are judged to misinterpret the infants’ mental states. Mothers’ individual stability (rank order stability) and group level continuity (mean level of stability across the infant ages) were assessed. Mothers showed modest temporal stability in both appropriate and non-attuned mind-mindedness over the infants’ first three months. The continuity of mind-mindedness showed that appropriate mind-mindedness increased over the infant ages, but non-attuned mind-mindedness showed no change. In infants’ early lives, mothers’ ability to accurately interpret their infants’ mental states is enhanced as the mother-infant relationship develops and infants become more communicative partners.     

Evolutionary roots of intuitive parenting: Maternal competence in chimpanzees

Intuitive parenting behaviours have been shown to be universal in humans and appear to be based on psychobiological preadaptedness. This study is an exploration of the evolutionary roots of intuitive parenting through naturalistic observation of mother chimpanzees' interaction with their very young infants. Maternal competence is demonstrated initially through the behaviours of carrying the newborn infant and allowing the infant to nurse. Very early mother–infant interactions include play, ‘exercise’, cradling and grooming. Chimpanzee mothers also assess their offspring's behavioural state and muscle tone through visual inspections and movement of legs, arms, fingers and toes. Chimpanzee mothers and infants, as early as 2 weeks of age, spend some time in mutual gaze. Neonatal chimpanzees are capable of sustained face-to-face interactions, as these were observed in nursery-reared chimpanzee interactions with human adults; however, it appears that chimpanzee mothers encourage mutual gaze with their infants for only brief durations. Chimpanzees with good maternal competence exhibit sensitive responsivity to infants' communicatory signals. Thus the results of this study support the claim that there are evolutionary and comparative foundations of intuitive parenting evident in the maternal behaviour and maternal competence of chimpanzees.     

The social functions of babbling: acoustic and contextual characteristics that facilitate maternal responsiveness

What is the social function of babbling? An important function of prelinguistic vocalizing may be to elicit parental behavior in ways that facilitate the infant's own learning about speech and language. Infants use parental feedback to their babbling to learn new vocal forms, but the microstructure of parental responses to babbling has not been studied. To enable precise manipulation of the proximal infant cues that may influence maternal behavior, we used a playback paradigm to assess mothers’ responsiveness to prerecorded audiovisual clips of unfamiliar infants’ noncry prelinguistic vocalizations and actions. Acoustic characteristics and directedness of vocalizations were manipulated to test their efficacy in structuring social interactions. We also compared maternal responsiveness in the playback paradigm and in free play with their own infants. Maternal patterns of reactions to babbling were stable across both tasks. In the playback task, we found specific vocal cues, such as the degree of resonance and the transition timing of consonant‐vowel syllables, predicted contingent maternal responding. Vocalizations directed at objects also facilitated increased responsiveness. The responses mothers exhibited, such as sensitive speech and vocal imitation, are known to facilitate vocal learning and development. Infants, by influencing the behavior of their caregivers with their babbling, create social interactions that facilitate their own communicative development.     

The development of infants' preference for motherese

Generally, infants prefer infant-directed (ID) to adult-directed (AD) speech. Mostly, researchers have used unfamiliar female voices in these studies. We investigated preferences for maternal ID speech in 1- and 4-month-olds. Using a procedure in which infants controlled access to voices by fixating a visual display, infants listened to recordings of natural female ID and AD speech. In Experiment 1, 1-month-olds heard recordings of maternal ID and AD speech, but these infants showed no preference for maternal ID speech. In Experiment 2, 1-month-olds heard the same ID and AD speech tapes but were not familiar with the speakers. Contrary to Experiment 1, these infants preferred ID speech. In Experiment 3, 4-month-olds heard recordings of maternal ID and AD speech and showed a significant preference for ID speech. Collectively, these results suggest that infant attention to ID speech depends on both speaker-general and speaker-specific characteristics, with interesting developmental changes occuring during early infancy.     

The development of referential offering in the first year

The ontogeny of referential offers was examined in a longitudinal, within dyad case study of two mother–infant pairs. A combination of microanalytic and qualitative methodologies was employed in describing the functions and morphology of this gesture, as well as its temporal and sequential organization with a number of infant and maternal behaviours. Offers were found to emerge from repetitive, exploratory play routines that provide infants with alternative visual perspectives on objects, and were facilitated by mothers' support of infants' immature attentional, motoric and arousal regulation capacities. Offers were observed to co. occur with maternal behaviours that direct and maintain infants' attention to objects. Our observations suggest that offers are transformed through guided interactions into conventional communicative gestures. Offering arises as mothers become part of the infants' exploratory play routines, gradually changing the function of the behaviour of the infants. These observations are consistent with dynamic systems models of development.     

Infants of chronically depressed mothers learn in response to male, but not female, infant-directed speech

Previous research using a conditioned-attention paradigm demonstrated that 4-month-old infants of depressed mothers (a) failed to acquire associations when a segment of their mothers' infant-directed (ID) speech signaled the presentation of a smiling face but (b) did acquire associations when a segment of an unfamiliar nondepressed mother's ID speech signaled the face (P. S. Kaplan, J. -A. Bachorowski, M. J. Smoski, & W. J. Hudenko, 2002). In the present study, 5- to 13-month-old infants of depressed mothers failed to acquire associations when either their own mothers' (Experiment 1) or an unfamiliar nondepressed mother's (Experiments 1 and 2) ID speech signaled a face. However, these infants acquired associations when a segment of an unfamiliar nondepressed father's ID speech served as the signal (Experiment 2). One possible explanation of these results is that infants of depressed mothers selectively "tune out" ID speech from their mothers and from other, nondepressed, women.     

Infants use meter to categorize rhythms and melodies: implications for musical structure learning

Little is known about whether infants perceive meter, the underlying temporal structure of music. We employed a habituation paradigm to examine whether 7-month-old infants could categorize rhythmic and melodic patterns on the basis of the underlying meter, which was implied from event and accent frequency of occurrence. In Experiment 1, infants discriminated duple and triple classes of rhythm on the basis of implied meter. Experiment 2 replicated this result while controlling for rhythmic grouping structure, confirming that infants perceived metrical structure despite occasional ambiguities and conflicting group structure. In Experiment 3, infants categorized melodies on the basis of contingencies between metrical position and pitch. Infants presented with metrical melodies detected reversals of pitch/meter contingencies, while infants presented with non-metrical melodies showed no preference. Results indicate that infants can infer meter from rhythmic patterns, and that they may use this metrical structure to bootstrap their knowledge acquisition in music learning.     

Prosody in Infant-Directed Speech Is Similar Across Western and Traditional Cultures

When speaking to infants, adults typically alter the acoustic properties of their speech in a variety of ways compared with how they speak to other adults; for example, they use higher pitch, increased pitch range, more pitch variability, and slower speech rate. Research shows that these vocal changes happen similarly across industrialized populations, but no studies have carefully examined basic acoustic properties of infant-directed (ID) speech in traditional societies. Moreover, some scholars have suggested that ID speech is culturally specific and does not exist in some small-scale societies. We examined fundamental frequency (F₀) production and speech rate in mothers speaking to both infants and adults in three cultures: Fijians, Kenyans, and North Americans. In all three cultures, speakers used higher F₀ when speaking to infants relative to when speaking to other adults, and they also used significantly greater F₀ variation and fewer syllables per second. Previous research has found that American mothers tend to use higher pitch than do mothers from other cultures, but when maternal education was controlled in the current study, we did not find a significant difference in average pitch across our three populations. This is the first research systematically comparing spontaneous ID and adult-directed speech prosody between Western and traditional societies, and it is consistent with a large body of evidence showing similar acoustic patterns in ID speech across industrialized populations.