An event-based analysis of the coordination of early infant vocalizations and facial actions

This study used an event-based approach to provide empirical evidence regarding the nature of coordination in 3- and 6-month-old infants. Vocalizations and facial actions of 12 normally developing infants interacting with their caregivers were coded. Coded vocalizations and facial actions were considered coordinated when they temporally overlapped. Results indicate that infants coordinated their vocalizations and facial actions more than expected by chance. Coordinated events were governed by 2 sequence patterns. When 2 communicative events were temporally associated across modalities, 1 event tended to be completely embedded within the other, and vocalizations tended to end before facial actions. This study provides new information about how infant communication is structured, confirms results from other coordination studies, and describes a new method for analysis of event-based data.     

Failure of selective attention to phonetic segments in consonant-vowel syllables

Subjects performed a two-choice speeded classification task that required selective attention to either the consonant or the vowel in synthetic consonant-vowel (CV) syllables. When required to attend selectively to the consonant, subjects could not ignore irrelevant variation in the vowel. Similarly, when required to attend selectively to the vowel, they could not ignore irrelevant variation in the consonant. These results suggest that information about an initial stop consonant and the following vowel is processed as an integral unit.     

Object labeling influences infant phonetic learning and generalization

Different kinds of speech sounds are used to signify possible word forms in every language. For example, lexical stress is used in Spanish (/‘be.be/, ‘he/she drinks’ versus /be.’be/, ‘baby’), but not in French (/‘be.be/ and /be.’be/ both mean ‘baby’). Infants learn many such native language phonetic contrasts in their first year of life, likely using a number of cues from parental speech input. One such cue could be parents’ object labeling, which can explicitly highlight relevant contrasts. Here we ask whether phonetic learning from object labeling is abstract—that is, if learning can generalize to new phonetic contexts. We investigate this issue in the prosodic domain, as the abstraction of prosodic cues (like lexical stress) has been shown to be particularly difficult. One group of 10-month-old French-learners was given consistent word labels that contrasted on lexical stress (e.g., Object A was labeled /‘ma.bu/, and Object B was labeled /ma.’bu/). Another group of 10-month-olds was given inconsistent word labels (i.e., mixed pairings), and stress discrimination in both groups was measured in a test phase with words made up of new syllables. Infants trained with consistently contrastive labels showed an earlier effect of discrimination compared to infants trained with inconsistent labels. Results indicate that phonetic learning from object labeling can indeed generalize, and suggest one way infants may learn the sound properties of their native language(s).     

Affiliative vocalizations in infant rhesus macaques (Macaca mulatta).

In Experiment 1, infant rhesus monkeys (Macaca mulatta) were separated and then reunited with mothers, united with a male, or placed in an empty cage. Infants girned more when with mothers or the male than when alone. Girns declined over time when infants were united with the male. Coo rates were high when the infant was alone or with the male. Shrieks, barks, and fear-related behavior were higher with the male. In Experiment 2 the vocalizations of infants were examined during separation when alone or when mothers or a male were in the same room. Infants cooed more when mothers or a male were present. Cooing increased over time, with a greater increase in the mothers' presence. Girns were given to both mothers and males, but more were given to mothers. Coos and girns are both affiliative vocalizations but are differentially modulated as infants cease cooing when they receive contact comfort.     

How the components of speaking rate influence perception of phonetic segments

In two studies we investigated the way in which the components of speaking rate, articulation rate and pause rate, combine to influence processing of the silence-duration cue for the voicing distinction in medial stop consonants. First, we replicated the finding that the articulation rate of a carrier sentence, that is, the rate at which the speech itself is produced, influences how the duration information is used to assign voicing values. Second, and more importantly, the assignment of voicing values was also influenced by the pause rate of the sentence. Thus, the listener adjusts for both articulation rate and pause rate when processing the phonetically relevant information. Finally, the two rate components did not function in an equivalent manner, since changes in articulation rate had considerably more effect on phonetic judgments than did changes in pause rate. Alternative explanations fo the relative weighting of the two variables are discussed.     

A phonetic approach to consonant repetition in early words

The goal of this study was to evaluate movement-based principles for understanding early speech output patterns. Consonant repetition patterns within children's actual productions of word forms were analyzed using spontaneous speech data from 10 typically developing American-English learning children between 12 and 36 months of age. Place of articulation, word level patterns, and developmental trends in CVC and CVCV repeated word forms were evaluated. Labial and coronal place repetitions dominated. Regressive repetition (e.g., [gag] for “dog”) occurred frequently in CVC but not in CVCV word forms. Consonant repetition decreased over time. However, the children produced sound types available reported as being within young children's production system capabilities in consonant repetitions in all time periods. Findings suggest that a movement-based approach can provide a framework for comprehensively characterizing consonant place repetition patterns in early speech development.     

Reception and transmission of infant vocalizations with dedicated telephone lines

A remote control home amplifier is described that allows the investigator to use dedicated telephone lines between the laboratory and the home to record infant vocalizations and provide auditory stimulation to the infant. The procedure allows daily test sessions with the infant, and several infants can be studied each day with one set of laboratory equipment.     

Beyond ba-ba and gu-gu: Challenges and strategies in coding infant vocalizations

Infant vocal behaviors are extremely complex. Consequently, coding these behaviors is difficult and is typically associated with low reliability across observers. Various difficulties that arise when dealing with prelinguistic vocalizations, especially in the first 6 months of life, are outlined here. A proposed database of digitized infant vocalizations that illustrates strategies used to deal with these difficulties is then described. These strategies are based on theoretical infraphonological constructs, empirical observations, and information about the nature of mature phonological systems. Furthermore, the strategies are open-ended and can be modified as new information becomes available regarding infant vocal behaviors. At present, a preliminary database is available on the Web that illustrates some of these strategies. As the database is expanded, it is expected to provide a general framework for observers to categorize infant vocalizations and thereby enhance observer reliability.     

The melody of surprise: maternal surprise vocalizations during play with her infant

Two groups of mothers and their infants (24 infants, mean age=3.5 months and 24 infants, mean age=5.5 months) were video‐ and audio‐taped in their homes while playing with a Jack‐in‐the‐box. The mean fundamental frequency of spontaneous surprise exclamations of mothers when opening the toy were analysed, and infant and maternal facial expressions of surprise were coded in three regions of the face. A t‐test established that significantly more of the older children in comparison with younger children showed surprise (t=?2.96, df=46, p<0.005, 2‐tailed). Twenty‐nine per cent of the younger infants, in comparison with 67% of the older children showed facial expressions of surprise. A t‐test of maternal pitch height (Hz) indicated that mothers exclaimed in surprise with a higher pitch when the child did not show a surprise facial expression (mean=415.61 Hz) in comparison with the child showing surprise (mean=358.97 Hz; t=2.9, df=46, p=0.006, 2‐tailed). A multiple regression established that infant's expression was a stronger predictor of maternal vocal pitch than was the age of the infant. These results are discussed in terms of maternal use of emotional expressions as ‘social signals’. Copyright © 2002 John Wiley & Sons, Ltd.     

The effects of infant simulators on early adolescents

The researchers examined the effects of infant simulators (computerized dolls designed to simulate normal infants) on 236 eighth-grade students. As part of their health and sex education curriculum, students had to provide care--24 hours a day, over several days--to dolls that cried when they "were hungry," "needed a diaper change," or "needed attention." The dolls enabled teachers to evaluate the care given by students. Students kept daily charts and journals, and wrote essays about their experiences. One to two years later, the students were surveyed, along with 461 comparison students who did not have the infant simulator experience. The findings indicated that the doll experience had a significant impact on the students, especially the females. It helped them to learn about the challenges of infant care, and to think of the implications before engaging in sexual intercourse. The comparison group felt less knowledgeable about what it takes to care for an infant, and judged infant care as less time consuming, difficult, and expensive than did those who had the infant simulator experience.     

Limits on phonetic integration in duplex perception

The telling fact about duplex perception is that listeners integrate into a unitary phonetic percept signals that are coherent from a phonetic point of view, even though the signals are, on purely auditory grounds, separate sources. Here we explore the limits on the integration of a sinusoidal consonant cue (theF3 transition for [da] vs. [ga]) with the resonances of the remainder of the syllable. Perceiving duplexly, listeners hear the whistle of the sinusoid, but also the [da] and [ga] for which the sinusoid provides the critical information. In the first experiment, phonetic integration was significantly reduced, but not to zero, by a precursor that extended the transition cue forward in time so that it started 50 msec before the cue. The effect was the same above and below the duplexity threshold (the intensity of sinusoid in the combined pattern at which the whistle was just barely audible). In the second experiment, integration was reduced once again by the precursor, and also, but only below the duplexity threshold, by harmonics of the cues that were simultaneous with it. The third experiment showed that the simultaneous harmonics reduced phonetic integration only by serving as distractors while also permitting the conclusion that the precursor produced its effects by making the cue part of a coherent and competing auditory pattern, and so “capturing” it. The fourth experiment supported this interpretation by showing that for some subjects the amount of capture was reduced when the capturing tone was itself captured by being made part of a tonal complex. The results support the assumption that the independent phonetic system will integrate across disparate sources according to the cohesive power of that system as measured against the evidence for separate sources.     

Gender differences in phonetic processing

In research on dyslexia, inadequate or inappropriate comparisons have often been made with control subjects, frequently overlooking important gender differences. More information is needed regarding the performance of control subjects, and adults, on measures purportedly assessing phonological and orthographic processing. Using tests similar to those used in dyslexic research, 20 female and 20 male college-age students were tested to examine gender differences in phonetic processing skills. The findings suggest that in equally competent readers, gender and other factors do play a significant role in determining the time it takes for phoneme manipulation and word identification. Females, especially those with poorer academic records, are significantly slower than males on measures typically used in dyslexic research. These findings show a need for a reexamination of control group equivalence (especially regarding gender), and further exploration of variables that might influence performance on these tasks.     

Gender differences in phonetic processing

In research on dyslexia, inadequate or inappropriate comparisons have often been made with control subjects, frequently overlooking important gender differences. More information is needed regarding the performance of control subjects, and adults, on measures purportedly assessing phonological and orthographic processing. Using tests similar to those used in dyslexic research, 20 female and 20 male college-age students were tested to examine gender differences in phonetic processing skills. The findings suggest that in equally competent readers, gender and other factors do play a significant role in determining the time it takes for phoneme manipulation and word identification. Females, especially those with poorer academic records, are significantly slower than males on measures typically used in dyslexic research. These findings show a need for a reexamination of control group equivalence (especially regarding gender), and further exploration of variables that might influence performance on these tasks.     

Lipread-induced phonetic recalibration in dyslexia

Auditory phoneme categories are less well-defined in developmental dyslexic readers than in fluent readers. Here, we examined whether poor recalibration of phonetic boundaries might be associated with this deficit. 22 adult dyslexic readers were compared with 22 fluent readers on a phoneme identification task and a task that measured phonetic recalibration by lipread speech (Bertelson, Vroomen, & De Gelder, 2003). In line with previous reports, we found that dyslexics were less categorical in the labeling of the speech sounds. The size of their phonetic recalibration effect, though, was comparable to that of normal readers. This result indicates that phonetic recalibration is unaffected in dyslexic readers, and that it is unlikely to lie at the foundation of their auditory phoneme categorization impairments. For normal readers however, it appeared that a well-calibrated system is related to auditory precision as the steepness of the auditory identification curve positively correlated with recalibration.     

Enhancing early communication through infant sign training

Existing research suggests that there may be benefits to teaching signing to hearing infants who have not yet developed vocal communication. In the current study, each of 4 infants ranging in age from 6 to 10 months was taught a simple sign using delayed prompting and reinforcement. In addition, Experiment 1 showed that 2 children independently signed in a variety of novel stimulus conditions (e.g., in a classroom, with father) after participating in sign training under controlled experimental conditions. In Experiment 2, crying and whining were replaced with signing when sign training was implemented in combination with extinction.     

Maternal sensitivity behavior and infant behavior in early interaction

Maternal sensitivity behavior and infant behavior in early interaction were investigated among 57 Finnish mother–child pairs. Their interaction was video‐recorded at home in free‐play situation when the infants were 3 months and 12 months of age, and evaluated using the Parent–Child Early Relational Assessment Scale (PCERA). Maternal sensitivity behavior was mainly related to infant's positive aspects of mood, social and play behavior, and visual contact, both at 3 months and 12 months of age. Even though maternal sensitivity behavior correlated to infant behavior at 3 months and 12 months, infant behavior at 3 months of age contributed to later maternal sensitivity behavior. ©2001 Michigan Association for Infant Mental Health.     

The temporal coordination of early infant communication

The ability to coordinate expressive behaviors is crucial to the development of social and emotional communication. Coordination involves systematic sequencing of behaviors from two different modalities that have some temporal overlap. A bootstrapping procedure was used to determine whether preverbal 3- and 6-month-old infants sequence vocalizations, gazes at their mothers' faces, and facial expressions into pairs of coordinated patterns nonrandomly. Smiles and frowns were highly coordinated with vocalizations. Smiles were also coordinated with gazes at mothers' faces, which became stronger with age. Vocalizations were not coordinated with gazes at mothers' faces. These findings illustrate the manner in which infants temporally coordinate communicative actions and provide new evidence that facial expressions (particularly smiles) are central to early infant communications.