Changing Opportunities for Learning in Everyday Life: Infant Body Position Over the First Year

Developmental theories depend on characterizing the input to potential learning mechanisms—infants’ everyday experiences. The current study employed a novel ecological momentary assessment (EMA) to measure two aspects of the physical context of those experiences: body position and location. Infant body position was selected because it relates to the development of a variety of other skills. Caregivers of 3‐, 6‐, 9‐, and 12‐month‐olds reported infants’ body position—held, supine, reclined, prone, sitting, or upright—in response to text message notifications over a week to capture infants’ experiences across the entire range of their daily activities. Findings revealed a tremendous disparity in the distribution of body position experiences over the first year. Younger infants spend more time held, supine, and reclined, whereas older infants spend more time sitting and upright. Body position experiences differed substantially between same‐age infants who possess a motor skill (e.g., ability to sit or walk) compared with those who did not, suggesting that developing motor skills change infants’ everyday experiences. Finally, the success of the methodology suggests that similar EMAs might be used to study a wide range of infants’ naturalistic experiences.     

Newborns' Cries are Unique to Individuals (But Not to Language Environment)

Human neonates exhibit individually distinctive patterns of variation—sometimes called cry “signatures”—in the acoustics of their cries. For tests of group differences (e.g., age, health status, or ambient language differences), the uniqueness of cry sounds to individuals means that multiple cries from same infant cannot appropriately be treated as independent events for analysis. This approach violates the assumption of independence that underlies many statistical techniques and runs the risk of uncovering “significant” group effects that do not actually exist. Nonetheless, publications continue to appear in which multiple cries from the same infant have been treated as independent events for analysis. To demonstrate the perils, we have compared the cries of infants born into a Mandarin Chinese language environment with cries of infants born into an American English language environment. We show (1) that treating each cry sound as an independent event yields numerous “significant” group effects and (2) that these effects all but disappear when cries are treated appropriately, as “nested” within individual infants. The latter outcome is in keeping with prevailing models of neonatal cry production and casts doubt on the claim that neonates alter their cries to match features of the language spoken in their environment.     

Relations Between Women's Depressive Symptoms and Perceptions of Infant Distress Signals Varying in Pitch

Fifteen nondepressed, 15 moderately depressed, and 15 severely depressed women rated tape‐recordings of a newborn infant's hunger cry digitally altered to increase in fundamental frequency in 100 Hz increments. Cries were rated on 4 perceptual (e.g., arousing‐not arousing) and 6 caregiving rating scale items (e.g., cuddle, feed) used in previous studies (Zeskind, 1983). Analyses of variance showed that, as cry pitch increased, cries were rated as more arousing, aversive, urgent, and sick sounding. Highest pitched cries received highest levels of caregiving interventions. Severely depressed women rated cries as less perceptually salient and less likely to elicit active caregiving responses. Interaction effects showed that severely depressed women were least responsive to highest pitched cries. These results suggest that women's depression may alter perceptions of infant distress signals, especially at times of greater infant distress.     

The Perceptions of Infant Distress Signals Varying in Pitch by Cocaine‐Using Mothers

Perceptual responses to infant distress signals were studied in 16 cocaine‐using and 15 comparison mothers. All mothers rated tape recordings of 48 replications of a newborn infant's hunger cry digitally altered to increase in fundamental frequency in 100‐Hz increments. Cries were rated on 4 perceptual (arousing, aversive, urgent, and sick) and 6 caregiving rating scale items (clean, cuddle, feed, give pacifier, pick up, and wait and see) used in previous studies. Analyses of variance showed that, as cry pitch increased, cries were rated as more arousing, aversive, and urgent sounding. The highest pitched cries received the highest ratings for caregiving interventions. Main effects for cocaine use showed cocaine‐using mothers (a) rated cries as less arousing, aversive, urgent, and sick; (b) indicated they were less likely to pick up or feed the infant; and (c) indicated they more likely to give the crying infant a pacifier or just “wait and see.” A Group x Cry Pitch interaction effect showed that mothers in the cocaine group gave higher ratings to wait and see as the pitch of the cries increased, whereas mothers in the comparison group gave lower ratings to wait and see as the pitch of the cries increased. These ratings indicate that cocaine‐using mothers found cries to be less perceptually salient and less likely to elicit nurturant caregiving responses. These results suggest that maternal cocaine use is associated with altered perceptions of infant distress signals that may provide the basis for differential social responsivity in the caregiving context.     

Parent and Nonparent Perception of the Multimodal Infant Cry

This study examined whether perceivers can detect infant distress in the visual and acoustic signals within the cry. Parent and nonparent perceivers rated distress in 3‐, 6‐, 8‐, and 12‐month‐old infants' cries that were manipulated to separate facial, vocal, and bodily action. Mean perceiver ratings differed for high‐ and low‐distress cries at each infant age on the basis of facial and vocal action, but not bodily movement. Perceivers rated the cry sound as more distressed and the cry face as less distressed with increasing infant age. Parents rated the cries as less distressed overall than did nonparents. The results suggest that information about distress is available for perceivers in the crying infant's face and voice.     

Body Representation in the First Year of Life

Like faces, bodies are significant sources of social information. However, research suggests that infants do not develop body representation (i.e., knowledge about typical human bodies) until the second year of life, although they are sensitive to facial information much earlier. Yet, previous research only examined whether infants are sensitive to the typical arrangement of body parts. We examined whether younger infants have body knowledge of a different kind, namely the relative size of body parts. Five‐ and 9‐month‐old infants were tested for their preference between a normal versus a proportionally distorted body. Nine‐month‐olds exhibited a preference for the normal body when images were presented upright but not when they were inverted. Five‐month‐olds failed to exhibit a preference in either condition. These results indicate that infants have knowledge about human bodies by the second half of the first year of life. Moreover, given that better performance on upright than on inverted stimuli has been tied to expertise, the fact that older infants exhibited an inversion effect with body images indicates that at least some level of expertise in body processing develops by 9 months of age.     

Evidence of the Face Inversion Effect in 4‐Month‐Old Infants

This study tested the presence of the face inversion effect in 4‐month‐old infants using habituation to criterion followed by a novelty preference paradigm. Results of Experiment 1 confirmed previous findings, showing that when 1 single photograph of a face is presented in the habituation phase and when infants are required to recognize the same photograph, no differences in recognition performance with upright and inverted faces are found. However, Experiment 2 showed that, when infants are habituated to a face shown in a variety of poses and are required to recognize a new pose of the same face, infants' recognition performances were higher for upright than for inverted faces. Overall, results indicate that, under some experimental conditions, 4‐month‐olds process faces differently according to whether faces are presented upright or inverted.     

Role of Clinical Diagnosis and Medication Use in Effects of Maternal Depression on Infant‐Directed Speech

Infant‐directed (ID) speech was recorded from mothers as they interacted with their 4‐ to 12‐month‐old infants. Hierarchical regression analyses revealed that two variables, age of the mother and mother's diagnosed depression, independently accounted for significant proportions of the variance in the extent of change in fundamental frequency (ΔF0). Specifically, depressed mothers produced ID speech with smaller ΔF0 than did nondepressed mothers, and older mothers produced ID speech with larger ΔF0 than did younger mothers. Mothers who were taking antidepressant medication and who were diagnosed as being in at least partial remission produced ID speech with mean ΔF0 values that were comparable to those of nondepressed mothers. These results demonstrate explicit associations between major depressive disorder and an acoustic attribute of ID speech that is highly salient to young infants.     

Mothers' Speech to Hearing‐Impaired Infants and Children With Cochlear Implants

This study investigated the effects of age, hearing loss, and cochlear implantation on mothers' speech to infants and children. We recorded normal‐hearing (NH) mothers speaking to their children as they typically would do at home and speaking to an adult experimenter. Nine infants (10–37 months) were hearing‐impaired and had used a cochlear implant (CI) for 3 to 18 months. Eighteen NH infants and children were matched either by chronological age (10–37 months) or hearing experience (3–18 months) to the CI children. Prosodic characteristics such as fundamental frequency, utterance duration, and pause duration were measured across utterances in the speech samples. The results revealed that mothers use a typical infant‐directed speech style when speaking to hearing‐impaired children with CIs. The results also suggested that NH mothers speak with more similar vocal styles to NH children and hearing‐impaired children with CIs when matched by hearing experience rather than chronological age. Thus, mothers are sensitive to hearing experience and linguistic abilities of their NH children as well as hearing‐impaired children with CIs.     

The effect of masks on the visual preference for faces in the first year of life

To prevent the spread of COVID-19, face masks were mandatory in many public spaces around the world. Since faces are the gateway to early social cognition, this raised major concerns about the effect face masks may have on infants' attention to faces as well as on their language and social development. The goal of the present study was to assess how face masks modulate infants' attention to faces over the course of the first year of life. We measured 3, 6, 9, and 12-month-olds’ looking behavior using a paired visual preference paradigm under two experimental conditions. First, we tested infants' preference for upright masked or unmasked faces of the same female individual. We found that regardless of age, infants looked equally long at the masked and unmasked faces. Second, we compared infants' attention to an upright masked versus an inverted masked face. Three- and 6-month-olds looked equally long to the masked faces when they were upright or inverted. However, 9- and 12-month-old infants showed a novelty preference for the inverted masked face. Our findings suggest that more experience with faces, including masked faces, leads to efficient adaptations of infants' visual system for processing impoverished social stimuli, such as partially occluded faces.     

The Relationship Between Processing Facial Identity and Emotional Expression in 8‐Month‐Old Infants

In Experiment 1, it was investigated whether infants process facial identity and emotional expression independently or in conjunction with one another. Eight‐month‐old infants were habituated to two upright or two inverted faces varying in facial identity and emotional expression. Infants were tested with a habituation face, a switch face, and a novel face. In the switch faces, a new combination of identity and emotional expression was presented. The results show that infants differentiated between switch and habituation faces only in the upright condition but not in the inverted condition. Experiment 2 provides evidence that infants’ nonresponse in the inverted condition can be attributed to their independent processing of facial identity and emotional expression. This suggests that infants in the upright condition processed facial identity and emotional expression in conjunction with one another.     

Body Structure Perception in Infancy

Structural cues, such as the relative size and arrangement of parts, are key aspects of adults' representation of human bodies, and they are used to derive significant social information such as age, sex, and attractiveness. Prior studies have not clearly addressed young infants' sensitivity to these body characteristics. In the current experiments, 3.5‐month‐olds exhibited a preference between images of intact bodies versus those with parts in wrong locations. Infants also discriminated between intact bodies and those with distorted part proportions. In both cases, infants discriminated when images were presented upright but not when they were inverted. These results indicate that infants are sensitive to the arrangement and size of human body parts at least by 3.5 months of age. Thus, contrary to some prior reports, body representation early in life is developed enough to include structural information.     

Experimenter Affective Expression and Gaze Following in 7‐Month‐Olds

The study of gaze following in infants younger than 12 months of age has emphasized the effects of gesture, type of target, and its position or placement. This experiment extends this literature by examining the effects of adults' affective expression on 7‐month‐olds' gaze following. The effects of 3 affective expressions—happy, sad, and neutral—on 7‐month‐olds' frequency of gaze following were examined. The results indicated that infants more frequently followed the gaze of an adult posing a neutral expression than that of an adult posing either a happy or a sad expression. The infants also looked proportionately longer toward the indicated target when the adult's expression was neutral. The results are interpreted in terms of infants' flexibility of attention.     

Changes in Preference for Infant‐Directed Speech in Low and Moderate Noise by 4.5‐ to 13‐Month‐Olds

Although a large literature discusses infants' preference for infant‐directed speech (IDS), few studies have examined how this preference might change over time or across listening situations. The work reported here compares infants' preference for IDS while listening in a quiet versus a noisy environment, and across 3 points in development: 4.5 months of age, 9 months of age, and 13 months of age. Several studies have suggested that IDS might help infants to pick out speech in the context of noise (Colombo, Frick, Ryther, Coldren, & Mitchell, 1995; Fernald, 1984; Newman, 2003); this might suggest that infants' preference for IDS would increase in these settings. However, this was not found to be the case; at all 3 ages, infants showed similar advantage (or lack thereof) for IDS as compared to adult‐directed speech when presented in noise versus silence. There was, however, a significant interaction across ages: Infants aged 4.5 months showed an overall preference for IDS, whereas older infants did not, despite listening to the same stimuli. The lack of an effect with older infants replicates and extends recent findings by Hayashi, Tamekawa, and Kiritani (2001), suggesting that the variations in fundamental frequency and affect are not sufficient cues to IDS for older infants.     

Let Me Go: The Influences of Crawling Experience and Temperament on the Development of Anger Expression

Infants’ emerging ability to move independently by crawling is associated with changes in multiple domains, including an increase in expressions of anger in situations that block infants’ goals, but it is unknown whether increased anger is specifically because of experience with being able to move autonomously or simply related to age. To examine the influence of locomotion on developmental change in anger, infants’ (N = 20) anger expressions during an arm restraint procedure were observed longitudinally at a precrawling baseline assessment and 2 and 6 weeks after the onset of crawling. Infant age at each crawling stage was unrelated to the frequency of anger expressed in response to arm restraint. At 6 weeks postcrawling onset, infants whose mothers rated them as temperamentally higher in distress to limitations, compared with those rated lower, showed a greater increase in the frequency of anger expressed during the arm restraint relative to earlier assessments and took longer to reduce the frequency of anger expressed when no longer restrained. Findings suggest that experience with autonomous crawling has an effect on anger expression, independent of age, and that a temperamental tendency to become distressed by limitations may exacerbate the effect of crawling on anger expression.     

Background Television and Infants’ Allocation of Their Attention During Toy Play

The effect of background television on 6‐ and 12‐month‐olds’ attention during 20 min of toy play was examined. During the first or second half of the session, a clip from a variety of commonly available television programs was presented. The duration and frequency of infants’ looks to the toys and to the television indicated that regardless of age or program content, background television frequently got, but did not hold the infants’ attention. An order effect indicated that infants looked longer at the television when it was available in the second half of the session. Examination of infants’ focused attention to the toys showed a reduction in the mean length of focused episodes when the television was on. A follow‐up of the infants at 24 months indicated greater resistance to distraction by the television during play. Data from the three ages showed that individual differences in the amount of viewing were moderately stable across age and across home and lab contexts.     

Maternal Tactile Stimulation and the Neurodevelopment of Low Birth Weight Infants

The purpose of this study was to determine the relationship of early maternal touch to the neurodevelopmental status of low birth weight (LBW) infants. One hundred and eight LBW infants and their mothers were videotaped during a typical feeding when the infant was 3 months old. This tape was used to analyze both the mother's touch and other facets of caregiving behavior using standardized coding systems. Data on perinatal medical risk were also acquired through chart review, and neurodevelopmental tests were administered to the infants at age 1 year. Results indicate that infants whose mothers used more stimulating touch during caregiving had better visual‐motor skills at 1 year of age. In addition, infants of mothers who touched them frequently had more advanced gross motor development. Findings suggest that stimulating and frequent touch may help to compensate for early neurosensory deficits and promote neurodevelopment for LBW infants. Infant birth weight made the strongest contribution to all measures of infant neurodevelopmental status at age 1 year.     

Infant Auditory Sensitivity to Pure Tones and Frequency‐Modulated Tones

It has been suggested that infants respond preferentially to infant‐directed speech because their auditory sensitivity to sounds with extensive frequency modulation (FM) is better than their sensitivity to less modulated sounds. In this experiment, auditory thresholds for FM tones and for unmodulated, or pure, tones in a background of noise were measured for 4‐month‐old infants using a conditioned response procedure. The FM tones swept from 150 to 275 Hz or from 150 to 550 Hz. The frequency of the pure tone was either 275 or 550 Hz. The results showed that infants were slightly, but significantly, more sensitive to the sounds that included 550 Hz than they were to the lower frequency sounds, whether or not the sound was frequency modulated. It appears that infants could be somewhat more sensitive to infant‐directed than to adult‐directed speech, not because of FM per se, but because the fundamental frequency excursions in infant‐directed speech extend into a higher frequency range than those in adult‐directed speech.     

Six‐Month‐Old Infants Prefer Speech with Raised Formant Frequencies

Voices can be characterized by their fundamental frequency as well as by speech timbre characteristics, such as formant frequencies. While infants' responses to fundamental frequency characteristics are well established, very little is known about how infants respond to changes in formant frequencies. This study tested whether 6‐month‐old infants prefer listening to speech with raised formant frequencies over speech with lowered formant frequencies. Naturally spoken utterances were acoustically manipulated to render raised‐formant and lowered‐formant stimuli that only differed in the formant frequencies, while keeping fundamental frequency and other acoustic characteristics constant. Infants in an infant‐controlled listening procedure listened longer to the raised‐formant than to the lowered‐formant stimuli. These results provide the first evidence that infants distinguish and show preferences for variations in formant frequencies in adult speech.     

Postural Position Constrains Multimodal Object Exploration in Infants

Recent research has revealed the important role of multimodal object exploration in infants' cognitive and social development. Yet, the real‐time effects of postural position on infants' object exploration have been largely ignored. In the current study, 5‐ to 7‐month‐old infants (N = 29) handled objects while placed in supported sitting, supine, and prone postures, and their spontaneous exploratory behaviors were observed. Infants produced more manual, oral, and visual exploration in sitting compared to lying supine and prone. Moreover, while sitting, infants more often coupled manual exploration with mouthing and visual examination. Infants' opportunities for learning from object exploration are embedded within a real‐time postural context that constrains the quantity and quality of exploratory behavior.