The potential role of robust face representations learned within families when searching for one's child in a crowd.

Own child's face is one of the most socially salient stimuli for parents, and a faster search for it than for other children's faces may help provide warmer and more sensitive care. However, it has not been experimentally examined whether parents find their child's face faster. In addition, although own child's face is specially processed, the search time for own child's face may be similar to that for other socially salient stimuli, such as own or spouse's faces. This study tested these possibilities using a visual search paradigm. Participants (parents) searched for their child's, own, spouse's, other child's, same-sex adult's, or opposite-sex adult's faces as search targets. Our findings indicate that both mothers and fathers identified their child's face more quickly than other children's faces. Similarly, parents found their own and spouse's faces more quickly than other adults' faces. Moreover, the search time for family members' faces increased with the number of faces on the search display, suggesting an attentional serial search. These results suggest that robust face representations learned within families and close relationships can support reduced search times for family members' faces.

Selective attention to the mouth of a talker in Japanese-learning infants and toddlers: Its relationship with vocabulary and compensation for noise.

Infants increasingly gaze at the mouth of talking faces during the latter half of the first postnatal year. This study investigated mouth-looking behavior of 120 full-term infants and toddlers (6 months-3 years) and 12 young adults (21-24 years) from Japanese monolingual families. The purpose of the study included: (1) Is such an attentional shift to the mouth in infancy similarly observed in Japanese environment where contribution of visual speech is known to be relatively weak? (2) Can noisy conditions increase mouth-looking behavior of Japanese young children? (3) Is the mouth-looking behavior related to language acquisition? To this end, movies of a talker speaking short phrases were presented while manipulating signal-to-noise ratio (SNR: Clear, SN+4, and SN-4). Expressive vocabulary of toddlers was obtained through their parents. The results indicated that Japanese infants initially have a strong preference for the eyes to mouth which is weakened toward 10 months, but the shift was later and in a milder fashion compared to known results for English-learning infants. Even after 10 months, no clear-cut preference for the mouth was observed even in linguistically challenging situations with strong noise until 3 years of age. In the Clear condition, there was a return of the gaze to the eyes as early as 3 years of age, where they showed increasing attention to the mouth with increasing noise level. In addition, multiple regression analyses revealed a tendency that 2- and 3-year-olds with larger vocabulary increasingly look at the eyes. Overall, the gaze of Japanese-learning infants and toddlers was more biased to the eyes in various aspects compared to known results of English-learning infants. The present findings shed new light on our understanding of the development of selective attention to the mouth in non-western populations.

Relationship between oxytocin and maternal approach behaviors to infants' vocalizations.

Infants communicate their emotions to caregivers mainly through vocalizations. Research has shown that maternal oxytocin levels relate to adaptive parenting; however, little empirical research exists regarding the effects of endogenous oxytocin levels on maternal responses to infant vocalizations. Thus, in this study, we examined the relationship between mothers' salivary oxytocin levels, subjective feelings, and behavioral response to infants' emotional vocalizations. Additionally, we examined the relationship between psychological traits and maternal behavioral responses to infant vocalizations. In this study, 39 mothers were asked to stand on a balance board while listening to infant vocalization stimuli, to measure movements of their center of pressure, an index of approach-avoidance behavior. Sixty infant vocalizations (laughter, crying, and neutral) were presented for 6 â€‹s each. Afterwards, participants were asked to rate their subjective responses to each stimulus (not aroused - aroused, displeased - pleased, not urgent - urgent, and healthy - sick). Maternal oxytocin levels were negatively correlated with anterior movement of the center of pressure in response to infants' crying and babbling vocalizations, though no relationship was found between maternal approach-avoidance behavior toward infant laughter and oxytocin levels. This study indicated that maternal approach behavior toward infant vocalizations varies as a function of maternal endogenous oxytocin and the type of infant vocalization.

Corrigendum: Touching! An Augmented Reality System for Unveiling Face Topography in Very Young Children.

[This corrects the article DOI: 10.3389/fnhum.2019.00189.].

Touching! An Augmented Reality System for Unveiling Face Topography in Very Young Children.

Developmental body topography, particularly of the face, is a fundamental research topic in the current decade. However, empirical investigation of this topic for very young children faces a number of difficulties related to the task requirements and technical procedures. In this study, we developed a new task to study the spatially-sensed position of facial parts in a self-face recognition task for 2.5- and 3.5-year-old children. Using the technique of augmented reality (AR) and 3D face tracking technology, we presented participants with their projected self-image on a screen, accompanied by a digital mark located on parts of their face. We prepared a cheerful visual and auditory reward on the screen when participants showed correct localization of the mark. We then tested whether they could indicate the position of the mark on their own faces and remain motivated for task repetition. To assess the efficacy of this task, 31 2.5- and 11 3.5-year-old children participated in this study. About half of the 2.5-year-olds and 80% of the 3.5-year-olds could perform more than 30 trials. Our new task, then, was to maintain young children's motivation for task repetition using the cheerful visual and auditory reward. The analysis of localization errors suggested the uniqueness of spatial knowledge of self-face in young children. The efficacy of this new task for studying the development of body image has been confirmed.

Differential Effects of Infant Vocalizations on Approach-Avoidance Postural Movements in Mothers.

Infant vocalization plays a pivotal role in communicating infant mood to parents and thereby motivating parenting responses. Although many psychological and neural responses to infant vocalization have been reported, few studies have examined maternal approach-avoidance behavior in response to infant vocalization. Thus, this research sought to determine how infant emotional vocalization affects maternal behavior. Twenty mothers participated in this behavioral study, all of whom had infants of 24 months old or less. In the experiment, they stood on a Balance Board that collected real-time data regarding center of pressure (COP), while listening to a series of infant vocalizations including cry, laugh, and babbling. They then listened to the same vocalizations for a second time and rated their felt emotions in response to each vocalization. The participants demonstrated significant postural movements of approaching in response to cry stimuli or to stimuli regarded as highly urgent. In contrast, they demonstrated postural movement of avoidance in response to laugh vocalization. These findings suggest that parenting behavior in response to infant emotional vocalization is regulated not by the pleasant-unpleasant axis but by the urgency of the stimulus.

The Use of Pitch Accent in Word-Object Association by Monolingual Japanese Infants.

This study investigated the lexical use of Japanese pitch accent in Japanese-learning infants. A word-object association task revealed that 18-month-old infants succeeded in learning the associations between two nonsense objects paired with two nonsense words minimally distinguished by pitch pattern (Experiment 1). In contrast, 14-month-old infants failed (Experiment 2). Eighteen-month-old infants succeeded even for sounds that contained only the prosodic information (Experiment 3). However, a subsequent experiment revealed that 14-month-old infants succeeded in an easier single word-object task using pitch contrast (Experiment 4). These findings indicate that pitch pattern information is robustly available to 18-month-old Japanese monolingual infants in a minimal pair word-learning situation, but only partially accessible in the same context for 14-month-old infants.

Pareidolia in infants.

Faces convey primal information for our social life. This information is so primal that we sometimes find faces in non-face objects. Such illusory perception is called pareidolia. In this study, using infants' orientation behavior toward a sound source, we demonstrated that infants also perceive pareidolic faces. An image formed by four blobs and an outline was shown to infants with or without pure tones, and the time they spent looking at each blob was compared. Since the mouth is the unique sound source in a face and the literature has shown that infants older than 6 months already have sound-mouth association, increased looking time towards the bottom blob (pareidolic mouth area) during sound presentation indicated that they illusorily perceive a face in the image. Infants aged 10 and 12 months looked longer at the bottom blob under the upright-image condition, whereas no differences in looking time were observed for any blob under the inverted-image condition. However, 8-month-olds did not show any difference in looking time under both the upright and inverted conditions, suggesting that the perception of pareidolic faces, through sound association, comes to develop at around 8 to 10 months after birth.

Perception of vowel length by Japanese- and English-learning infants.

This study investigated vowel length discrimination in infants from 2 language backgrounds, Japanese and English, in which vowel length is either phonemic or nonphonemic. Experiment 1 revealed that English 18-month-olds discriminate short and long vowels although vowel length is not phonemically contrastive in English. Experiments 2 and 3 revealed that Japanese 18-month-olds also discriminate the pairs but in an asymmetric manner: They detected only the change from long to short vowel, but not the change in the opposite direction, although English infants in Experiment 1 detected the change in both directions. Experiment 4 tested Japanese 10-month-olds and revealed a symmetric pattern of discrimination similar to that of English 18-month-olds. Experiment 5 revealed that native adult Japanese speakers, unlike Japanese 18-month-old infants who are presumably still developing phonological perception, ultimately acquire a symmetrical discrimination pattern for the vowel contrasts. Taken together, our findings suggest that English 18-month-olds and Japanese 10-month-olds perceive vowel length using simple acoustic?phonetic cues, whereas Japanese 18-month-olds perceive it under the influence of the emerging native phonology, which leads to a transient asymmetric pattern in perception.

Audiovisual matching of lips and non-canonical sounds in 8-month-old infants.

Japanese 8-month-olds were tested to investigate the matching of particular lip movements to corresponding non-canonical sounds, namely a bilabial trill (BT) and a whistle (WL). The results showed that the infants succeeded in lip-voice matching for the bilabial trill, whereas they failed to do so for the whistle.

Age-related changes in sensitivity to native phonotactics in Japanese infants.

Japanese infants at the ages of 6, 12, and 18 months were tested on their ability to discriminate three nonsense words with different phonotactic status: canonical keetsu, noncanonical but possible keets, and noncanonical and impossible keet. The results showed that 12 and 18 months olds discriminate the keets/keetsu pair, but infants in all age groups fail to discriminate the keets/keet pair. Taken together with the findings in our previous study [Kajikawa et al., J. Acoust. Soc. Am. 120(4), 2278-2284 (2006)], these results suggest that Japanese infants develop the perceptual sensitivity for native phonotactics after 6 months of age, and that this sensitivity is limited to canonical patterns at this early developmental stage.

Longitudinal developmental changes in spectral peaks of vowels produced by Japanese infants.

This paper describes a longitudinal analysis of the vowel development of two Japanese infants in terms of spectral resonant peaks. This study aims to investigate when and how the two infants become able to produce categorically separated vowels, and covers the ages of 4 to 60 months in order to provide detailed findings on the developmental process of speech production. The two lower spectral peaks were estimated from vowels extracted from natural spontaneous speech produced by the infants. Phoneme labeled and transcription-independent unlabeled data analyses were conducted. The labeled data analysis revealed longitudinal trends in the developmental change, which correspond to the articulation positions of the tongue and the rapid enlargement of the articulatory organs. In addition, the distribution of the two spectral peaks demonstrates the vowel space expansion that occurs with age. An unlabeled data analysis technique derived from the linear discriminant analysis method was introduced to measure the vowel space expansion quantitatively. It revealed that the infant's vowel space becomes similar to that of an adult in the early stages. In terms of both labeled and unlabeled properties, these results suggested that infants become capable of producing categorically separated vowels by 24 months.

Cross-language sensitivity to phonotactic patterns in infants.

This study explored sensitivity to word-level phonotactic patterns in English and Japanese monolingual infants. Infants at the ages of 6, 12, and 18 months were tested on their ability to discriminate between test words using a habituation-switch experimental paradigm. All of the test words, neek, neeks, and neekusu, are phonotactically legitimate for English, whereas the first two words are critically noncanonical in Japanese. The language-specific phonotactical congruence influenced infants' performance in discrimination. English-learning infants could discriminate between neek and neeks at the age of 18 months, but Japanese infants could not. There was a similar developmental pattern for infants of both language groups for discrimination of neek and neeks, but Japanese infants showed a different trajectory from English infants for neekusu/neeks. These differences reflect the different status of these word patterns with respect to the phonotactics of both languages, and reveal early sensitivity to subtle phonotactic and language input patterns in each language.

Baby arithmetic: one object plus one tone.

Recent studies using a violation-of-expectation task suggest that preverbal infants are capable of recognizing basic arithmetical operations involving visual objects. There is still debate, however, over whether their performance is based on any expectation of the arithmetical operations, or on a general perceptual tendency to prefer visually familiar and complex displays. Here we provide new evidence that 5-month-old infants recognize basic arithmetic operations across sensory modalities. Using a violation-of-expectation task that eliminated the possibility of the familiarity and complexity preference, 5-month-old infants were presented alternatively with two types of arithmetical events: the expected, correct outcomes of operations (1 object+1 tone=2 objects and 1 object+2 tones=3 objects) and the unexpected, incorrect ones (1 object+2 tones=2 objects and 1 object+1 tone=3 objects). Results showed that subjects looked significantly longer at the unexpected events than at the expected events, suggesting that infants are able to recognize basic arithmetic operations across sensory modalities.