The relation between neonatal heart period patterns and developmental outcome

Developmental psychophysiologists have long been interested in a means for evaluating infants at risk for cognitive disabilities. The current research addressed the utility of a noninvasive measure of cardiac vagal tone in predicting developmental outcome. At 40 weeks conceptional age, 3 min of resting EKG were recorded from 80 infants. Four groups of infants were evaluated: prematures who had no medical complications in the postnatal period; prematures who experienced respiratory distress syndrome during the postnatal period; term infants who experienced birth asphyxia during labor and/or postdelivery; and healthy term infants. The mental scale of the Bayley Scales of Mental Development was administered at 8 and 12 months conceptional age. Heart period data were analyzed to derive mean heart period, heart period variability, and estimates of vagal tone for each subject. Analyses of the relationship between the heart period variables and 8- and 12-month outcome (i.e., Bayley Scales) indicated that infants with high vagal tone at 40 weeks conceptional age always had positive developmental outcome at both eight and 12 months of age. Infants with low vagal tone had varied outcomes. Measures of medical complications and other measures of heart period variability were not related to developmental outcome. The results suggest that measurement of cardiac vagal tone may provide an important means for assessing risk in birth stressed populations.     

Neonatal pain cries: effect of circumcision on acoustic features and perceived urgency

The relation between neonatal cry features elicited by painful circumcision procedures and the perceived urgency of those cries was investigated. Vocalizations were recorded during circumcision of 30 normal newborn males, analyzed by spectrographic methods and validated with computer techniques. The most invasive procedures elicited significantly longer crying bouts; shorter quiet intervals; shorter, more frequent vocalizations; higher peak fundamental frequencies; fewer harmonics; and greater variability of the fundamental. Cries elicited by the most intrusive procedures were judged by adult listeners to be the most urgent, and cries from similarly invasive procedures were judged to be of the same degree of urgency. Cries appeared to be judged along 3 dimensions described by harmonic, temporal, and pitch characteristics. Subjective judgments and objective quantitative data converge to demonstrate that infants' cries are perceived as varying and, objectively, do systematically vary with respect to the intensity of painful stimuli.     

The effects of within-group and between-group methodologies in the study of perceptions of infant crying

Recent studies have indicated that various infant cry patterns can be reliably distinguished when directly compared with other infant cry patterns. The purpose of this study was to compare the effects of this within-group method of cry presentation (in which listeners are exposed to 2 types of cry patterns) with the effects of a between-group methodology (in which listeners are exposed to only 1 type of infant cry pattern). 4 groups of adult listeners rated the tape-recorded cries of low- and high-risk infants on 4 Likert-type scale items during experimental phases. In phase 1, subjects were exposed to either the cries of low-risk or high-risk infants but not both. In phase 2, subjects were exposed to both low-risk and high-risk infant cries. In phase 3, subjects were exposed to the cries they heard in phase 1. Whereas all scale items differentiated the low- and high-risk infant cries during the within-group analyses of phase 2, all scale items did not differentiate low- and high-risk infant cries during the between-group phase of the experiment. The specific pattern of results indicate that within-group methods of cry presentation accentuate the perceptual distance among cry types and may actually create many reliable differences that would not be found in between-group comparisons.     

Acoustic Characteristics of Naturally Occurring Cries of Infants with "Colic"

Although infantile colic has long been defined by a perceived excessive amount of crying, acoustic attributes of the cry sound may also contribute to perceptions that this early social behavior is excessive or problematic. From an original sample of 76 infants (38 infants referred to physicians for problematic crying, or "colic," and 38 pair-matched comparison infants), 48 infants who produced naturally occurring cry bouts both before and after an evening feeding were studied: 11 infants with Wessel's colic, 15 infants with non-Wessel's colic, and 22 comparison infants. Standard and vociferous cry segments were selected from up to 2 min of tape-recorded crying for spectrum analysis. Vociferous cry segments had a longer duration, a higher fundamental frequency, and a greater percentage of dysphonation than did standard segments. No differences between infant groups were found in cries before feeding. After feeding, infants who were problematic criers, independent of Wessel's criteria, showed a greater percentage of dysphonation in the vociferous cry segment than did comparison infants. This finding resulted from a decrease in dysphonation in the cries of comparison infants after feeding and an increase in those of infants with non-Wessel's colic. The dominant frequency also increased after feeding in the vociferous cries of infants with Wessel's colic, resulting in these infants having higher-pitched cries after feeding than infants in the other 2 groups. Results indicate that infants who are perceived to have problematic crying have objectively different acoustic features in their cry sounds that are particularly aversive, and that complaints about excessive crying cannot be accounted for simply on the basis of reporting bias in overly concerned or emotionally labile parents.     

Neonatal Stress Reactivity: Predictions to Later Emotional Temperament

To investigate the relations among popular measures of neonatal stress and their link to subsequent temperament, 50 full-term newborns from a normal care nursery were examined responding to a heelstick blood draw. Baseline and heelstick measures of behavioral state, heart period, vagal tone, and salivary cortisol were obtained. Recovery measures of behavioral and cardiac activity were also analyzed. Mothers completed Rothbart's Infant Behavior Questionnaire when their infants reached 6 months of age. Baseline vagal tone predicted cortisol in response to the heelstick, suggesting that baseline vagal tone reflects the infants' ability to react to stressors. Greater reactivity to the heelstick (more crying, shorter heart periods, lower vagal tone, and higher cortisol) was associated with lower scores on "Distress-to-Limitations" temperament at 6 months. This finding was consistent with the expectation that the capacity to react strongly to an aversive stimulus would reflect better neurobehavioral organization in the newborn. Recovery measures of cardiac activity approximated and were correlated with baseline measures indicating the strong self-righting properties of the healthy newborn. Finally, vagal tone and salivary cortisol measures were not significantly related, suggesting the importance of assessing both systems in studies of the ontogeny of stress-temperament relations.     

Psychophysiological and perceptual responses to infant cries varying in pitch: comparison of adults with low and high scores on the Child Abuse Potential Inventory.

Based on their scores on the Child Abuse Potential (CAP) Inventory, 30 nonparent adults were classified as either having high CAP scores (n = 15) or low CAP scores (n = 15). Subjects' heart rate and skin conductance were assessed as they listened to audio-taped presentations of four "normal" phonated infant cries and four high-pitched, hyperphonated infant cries. Subjects also rated the cries on several perceptual items. Results showed that both groups of subjects found hyperphonated cries more aversive, distressing, urgent, arousing, and sick than phonated cry sounds. Similarly, all listeners' showed higher skin conductance levels (SCL) in response to hyperphonated than phonated cries. SCL became attenuated over time in response to phonated, but not hyperphonated, cries. Adults in the high-CAP group, showed marginally higher heart rates than low-CAP adults following presentation of all infant cry sounds and responded to phonated cries with marginally higher skin conductance levels than low-CAP adults. The responses of high-CAP nonparent adults are similar to those of parents with histories of physically abusive interactions with their infants.     

Physiological self-regulation and information processing in infancy: cardiac vagal tone and habituation

This study investigates the role of physiological self-regulation (cardiac vagal tone) in information processing (habituation) in 81 infants. Nucleus ambiguus vagal tone (Vna, a measure of respiratory sinus arrhythmia) was used to index cardiac vagal tone. Physiological self-regulation was operationalized as the change in Vna from a baseline period of measurement to habituation. Decreases in Vna consistently related to habituation efficiency, operationalized as accumulated looking time (ALT), in all infants twice at 2 months and twice at 5 months; however, this relation was accounted for by infants who met an habituation criterion on each task. Among habituators, shorter lookers also had greater Vna suppression during habituation. Within-age and between-age suppression of vagal tone predicted ALT, but ALT did not predict suppression of vagal tone. Physiological self-regulation provided by the vagal system appears to play a role in information processing in infancy as indexed by habituation.     

Cognitive Set and Coping Strategy Affect Mothers' Sensitivity to Infant Cries: A Signal Detection Approach

We used Signal Detection methodology to examine how cognitiveset affects mothers' response to an infant cry. We asked whether a cry from a "difficult" versus an "easy" infant would elicit a change in sensitivity or response bias in mother processing of these cries. Thirty-eight mothers of 4- to 6-month-old infants participated in a Signal Detection task in which they were asked whether they could detect differences between a standard cry and 1 to 4 cry variants. Cry variants differed from the standard cry in small, systematic changes in fundamental frequency. The task was conducted in 2 parts; each part constituted a condition wherein mother received a cognitive set manipulation that labeled the identical cry as coming from either a'difficult'or an "easy" infant. An increase in mothers' sensitivity was associated with the "difficult" infant cognitive set. We examined as well how a coping strategy(illusion of control) affected cry signal processing. Mothers who Exhibited high illusory control were least -sensitive in detecting differences between cries. Two information-prcessing, measures response time and heart rate, were also collected and showed that greater sensitivity was associated with more efficient processing of the cry signal.     

Verbal and Behavioral Responsiveness to the Cries of Atypical Infants

A total of 176 subjects (53 male students, 65 female students, and 58 mothers) were exposed to 1 of 6 types of infant cries coming from an adjacent room while their behavioral and affective responses were observed. The cries were the pain cries of 2 normal newborns, 1 infant with maladie du cri du chat, 1 with Down syndrome, 1 asphyxiated infant with brain damage, and one asphyxiated infant without brain damage. Subsequently the subjects rated the overhead cry on a series of affective, attributional, and perceptual dimensions. The results indicated that the 6 cries differentially affected the subjects' affective, self-reported, and behavioral responses, as well as their tendency to report not hearing the cry. In general, the findings suggested that the highest- pitched cries (those of the asphyxiated infants), in comparison to the lowest-pitched cries (those of the normal and Down infants), elicited less optimal responses from the listeners.     

Neurobehavioral Syndromes in Cocaine-exposed Newborn Infants

The effects of fetal cocaine exposure on newborn cry characteristics were studied in 80 cocaine-exposed and 80 control infants. The groups were stratified to be similar on maternal demographic characteristics and maternal use of other illegal substances and alcohol during pregnancy. The hypothesis was that excitable cry characteristics were related to the direct effects of cocaine, while depressed cry characteristics were related to the indirect effects of cocaine secondary to low birthweight. Structural equation modeling (EQS) showed direct effects of cocaine on cries with a longer duration, higher fundamental frequency, and a higher and more variable first formant frequency. Indirect effects of cocaine secondary to low birthweight resulted in cries with a longer latency, fewer utterances, lower amplitude, and more dysphonation. Cocaine-exposed infants had a lower birthweight, shorter length, and smaller head circumference than the unexposed controls. Findings were consistent with the notion that 2 neurobehavioral syndromes, excitable and depressed, can be described in cocaine-exposed infants, and that these 2 syndromes are due, respectively, to direct neurotoxic effects and indirect effects secondary to intrauterine growth retardation.     

Associations Between First‐Time Expectant Women's Representations of Attachment and Their Physiological Reactivity to Infant Cry

Associations among 53 primiparous women's Adult Attachment Interview classifications (secure–autonomous vs. insecure–dismissing) and physiological and self‐reported responses to infant crying were explored. Heart rate, skin conductance levels, and respiratory sinus arrhythmia (RSA) were recorded continuously. In response to the cry, secure–autonomous women demonstrated RSA declines, consistent with approach‐oriented responses. Insecure–dismissing women displayed RSA and electrodermal increases, consistent with behavioral inhibition. Furthermore, insecure–dismissing women rated the cries as more aversive than secure–autonomous women. Nine months postpartum, secure–autonomous women, who prenatally manifested an approach‐oriented response to the unfamiliar cry stimulus, were observed as more sensitive when responding to their own distressed infant, whereas women classified prenatally as insecure–dismissing were observed as less sensitive with their own infants.     

Infant Crying and Adults'' Anticipated Caregiving Responses: Acoustic and Contextual Influences

These studies assessed adults' latencies to signal that they would respond to infant crying as functions of (1) the degree of infant distress they perceived in the cry, and (2) contextual information relevant to caregiving. In the first study (N = 34), listeners waited longer to respond to cries that they had earlier rated as sounding less distressed than when they heard cries of higher distress. Further, those who had been told that the infant needed sleep waited longer to respond than those without this information. This effect of context information, however, was limited to the latencies; in another study (N = 50), listeners' ratings of distress were not affected. Several acoustic features of the cries correlated with distress ratings and with latencies to signal a caregiving response. Taken together, the results suggest that adults' responses to crying are influenced both by acoustic gradations in the cry itself and by the caregiving context. Ratings of degree of distress manifest in the cry, in other words, may be highly predictive of caregiving behavior but not wholly so. Finally, although certain acoustic variations related to greater perceived distress and speed of response, differences were apparent between infants in the magnitude of these variations. The implication that the general process of cry perception may be calibrated, or fine tuned, to the range of acoustic variation provided by individual infants is discussed.     

Embracing the Biological Roots of the Infant’s Cry

SYNOPSIS

Across species of mammals, the cry of a young infant has profound effects on the parent’s brain, physiology, emotions, and behavior. High levels of infant crying can trigger increases in testosterone in men, which is accompanied by less sensitive caregiving. By learning about the biological roots and essential functions of the infant’s cry, parents may be empowered to take steps to manage the stress that is inherently induced by these cries.     

Effects of marijuana use during pregnancy on newborn cry

The effects of maternal marijuana use on the newborn cry were studied in Jamaica, where it was possible to rule out confounding factors such as the use of other substances and demographic variables that have clouded previous studies and where higher dosages may make the effects more visible. The acoustic characteristics of the cries of 20 infants of marijuana users and 20 controls were analyzed. The cries of the infants of marijuana users were shorter, had a higher percentage of dysphonation, a higher and more variable fundamental frequency, and a lower first formant than controls. There was also a dose response relation between the first formant and marijuana use. We suggest that heavy marijuana use affects the neurophysiological integrity of the infant.     

Adult Perception of Emotion Intensity in Human Infant Cries: Effects of Infant Age and Cry Acoustics

The relation between adult perception of emotion intensity in the cries of 1- and 6-month-old infants and the acoustic characteristics of the cries was examined. In the first study, adults who were inexperienced in child care rated 40 cries on 3 emotion intensity scales: anger, fear, and distress. The cries of 6-month-olds were rated as being significantly more intense. Different acoustic variables accounted for emotion intensity ratings for the 2 infant ages. Peak amplitude and noisiness of the cry predicted adult judgments of intensity ratings of 1-month-olds' cries; a measure of amplitude ratio (in 2 frequency bands) was the best predictor of intensity ratings of 6-month-olds' cries. In the second study, parents of infants rated the same cries on the same scales. They also rated the older infants' cries as being more intense. The 2 adult groups did not differ on their ratings, and a regression equation derived from one adult group predicted the other adult group's rating of the same infant age better than it predicted its own ratings for the other infant age. Infant age, and its associated acoustic features, seems to be a more important determinant of adults' perception of emotion intensity than are such adult characteristics as gender or infant-care experience.     

Adult perceptions of pain and hunger cries: a synchrony of arousal

180 male and female nonparent adults rated tape-recordings of the initial, middle, and final 10-sec segments of pain and hunger cries on 4 7-point Likert-type scale items describing how urgent, arousing, aversive, and sick the cry segments sounded. Multivariate analyses of variance showed that the final segment of the pain cry was perceived as less urgent, arousing, and aversive than the initial and middle segments. The hunger cry was perceived as increasingly more urgent, arousing, and aversive from the initial to the middle to the final cry segments, with the final segment receiving higher ratings than the final segment of the pain cry. The middle segment of both cries was the most sick sounding. While females were more aroused than males as the hunger cry intensified, and females were less aroused than males as the pain cry subsided, the initial segments of the pain cry were particularly potent stimuli to both males and females. These results suggest that different segments of cries resulting from the same stimulus provide different messages that communicate the presumed level of infant arousal.     

Children's emotions and behaviors in response to infants' cries

Infant crying can elicit in others both a range of emotions and contrasting behavioral reactions, such as altruistic caregiving versus aggression. Variations in reactions to young infants' cries were examined in 60 children ranging in age from late preschool to preadolescence. Each child over-heard either a preterm or a full-term tape-recorded cry from an adjacent room. Then a mother, carrying her infant, came looking for her (previously) "crying" infant's bottle. Later each child was interviewed after hearing a tape recording of a preterm and a full-term cry. Children's emotions and behaviors thus were assessed in response to simulated, real distresses and hypothetical representations of distress. Children's self-reports of empathy, their verbalized intentions to help, their actual helping responses, and observers' ratings of negative emotion were common responses to cries at all ages. In addition there were significant increases with age in prosocial, behavioral interventions. Expressions of negative emotion were inversely related to subsequent forms of prosocial behavior that required direct interaction with the infant. The emotions and behaviors of most children were not influenced by whether they heard preterm or full-term cries. They were, however, able to discriminate between such cries and some articulated "theories" about the impact of the cries on the listener.     

Cross-cultural differences in maternal perceptions of cries of low- and high-risk infants

The tape-recorded cries of low- and high-risk newborn infants were rated by 150 inner-city Anglo-American, Black-American, and Cuban-American mothers during the hospital lying-in period following childbirth. Half of each cultural group was primiparous and half was multiparous. The mothers rated the cries along 4 perceptual and 6 caregiving response scale items. Reliable differences were found between low- and high-risk infant cries on all perceptual responses with the effects of culture and parental experience affecting the degree of differences. Generally, Anglo-American mothers found the cries more distressing, urgent, arousing, and sick sounding than Black-American mothers, while Cuban-American mothers showed similarities to both Black- and Anglo-American mothers depending on the scale items. The ratings on the caregiving response scale items paralleled cultural differences found on the perception scale items and previous reports of the mother-infant interaction patterns of other Anglo-, Black-, and Cuban-American samples. The results are discussed as being important in developing nonethnocentric views of the functional significance of the behaviors of the infant at risk, yet as providing evidence of the cross-cultural significance of the cry sound of the infant at risk.     

Gene-environment contributions to the development of infant vagal reactivity: the interaction of dopamine and maternal sensitivity

This study investigated dopamine receptor genes (DRD2 and DRD4) and maternal sensitivity as predictors of infant respiratory sinus arrhythmia (RSA) and RSA reactivity, purported indices of vagal tone and vagal regulation, in a challenge task at 3, 6, and 12 months in 173 infant-mother dyads. Hierarchical linear modeling (HLM) revealed that at 3 and 6 months, RSA withdrawal in response to maternal separation was greater (suggesting expected physiological regulation) in infants without the DRD2 risk allele than those with the risk allele. At 12 months, infants with the risk allele who were also exposed to maternal sensitivity showed levels of RSA withdrawal comparable to infants who were not at genetic risk. Findings demonstrate the importance of developmental analysis of gene-environment interaction.     

On the importance of fundamental frequency and other acoustic features in cry perception and infant development

This study examined acoustic correlates of adults' ratings of infants' cries. Parents and nonparents rated 12 spontaneous cries from young infants on 8 items describing the cries' aversiveness and on 9 semantic differential items. The results indicated that the duration, the amount of dysphonation, and proportion of energy in various frequency bands were highly correlated with adults' ratings. Further, the pattern of correlations between each of the 17 rating scale items and the acoustic attributes was virtually the same, suggesting that the items represented a single underlying dimension of perceived aversiveness. Finally, no differences were found between the results for parents and nonparents. General issues in the study of cry perception are discussed.