Pi ka pu: The perception of speech sounds by prelinguistic infants

Attention, Perception, & Psychophysics - Experimentation with 14–18-week-old infants indicates that they are capable of grouping together syllables of English depending on whether the...     

Size constancy in infants: 4-month-olds' responses to physical versus retinal image size

This study tested whether 4-month-old infants respond primarily to objects' physical or retinal image sizes. In the study's main experiment, infants were habituated to either a 6-cm-diameter disk at a distance of 18 cm or a 10-cm disk at 50 cm. They were then given 2 test trials in which the 6- and 10-cm disks were presented side by side at a distance of 30 cm. For each infant, one test object had a novel physical size but a familiar retinal image size, and the other had a familiar physical size but a novel retinal image size. The infants exhibited a significant looking preference for the object that had a novel physical size. A preliminary experiment found that 4-month-olds' looking preferences are based on novelty, not familiarity, under the conditions of this study. Given this finding, the results suggest that 4-month-old infants attend and respond primarily to physical size, not to retinal image size.     

A prelinguistic gestural universal of human communication

Several cognitive accounts of human communication argue for a language-independent, prelinguistic basis of human communication and language. The current study provides evidence for the universality of a prelinguistic gestural basis for human communication. We used a standardized, semi-natural elicitation procedure in seven very different cultures around the world to test for the existence of preverbal pointing in infants and their caregivers. Results were that by 10-14 months of age, infants and their caregivers pointed in all cultures in the same basic situation with similar frequencies and the same proto-typical morphology of the extended index finger. Infants' pointing was best predicted by age and caregiver pointing, but not by cultural group. Further analyses revealed a strong relation between the temporal unfolding of caregivers' and infants' pointing events, uncovering a structure of early prelinguistic gestural conversation. Findings support the existence of a gestural, language-independent universal of human communication that forms a culturally shared, prelinguistic basis for diversified linguistic communication.     

Origins of "us" versus "them": prelinguistic infants prefer similar others

A central feature of human psychology is our pervasive tendency to divide the social world into "us" and "them". We prefer to associate with those who are similar to us over those who are different, preferentially allocate resources to similar others, and hold more positive beliefs about similar others. Here we investigate the developmental origins of these biases, asking if preference for similar others occurs prior to language and extensive exposure to cultural norms. We demonstrate that, like adults, prelinguistic infants prefer those who share even trivial similarities with themselves, and these preferences appear to reflect a cognitive comparison process ("like me"/"not like me"). However, unlike adults, infants do not appear to prefer others with an utterly arbitrary similarity to themselves. Together, these findings suggest that the phenomena of ingroup bias, and enhanced interpersonal attraction toward those who resemble ourselves, may be rooted in an inherent preference for similarity to self, which itself may be enhanced during development by the influence of cultural values.     

Different patterns of contingent stimulation differentially affect attention span in prelinguistic infants

The ability to sustain attention influences different domains including cognitive, motor, and communicative behavior. Previous research has demonstrated how an infant's parent can influence sustained attention. The purpose of our study was to expose infants systematically to both sensitive and redirective patterns of behavior to examine how unfamiliar individuals could influence attention. Results revealed infants changed their patterns of looking with the unfamiliar individuals. Infants had longer durations of sustained attention when interacting with a sensitive unfamiliar individual who followed into their attentional focus as opposed to an intrusive person who led their attentional focus. This study demonstrates that infants discriminate patterns of contingency to persons seen for only a short period of time broadening the range of potential mentors for learning.     

Language development in Down syndrome: from the prelinguistic period to the acquisition of literacy

Down syndrome (DS) is associated with abnormalities in multiple organ systems and a characteristic phenotype that includes numerous behavioral features. Language, however, is among the most impaired domains of functioning in DS and, perhaps, also the greatest barrier to independent meaningful inclusion in the community. In this article, we review what is known about the extent, nature, and correlates of the language and related problems of individuals with Down syndrome. In doing so, we focus largely on the syndrome-specific features of the language phenotype, although we also consider within-syndrome variation. The review focuses on the prelinguistic foundations of language and the major components of language (i.e., vocabulary, syntax, and pragmatics). We also consider two topics in the treatment and education of individuals with DS: prelinguistic communication intervention and the acquisition of literacy skills.     

The vocal repertoire of preterm infants: Characteristics and possible applications

We investigated infants’ capacities to express themselves orally at very early developmental stages. Most reports focus on crying when in pain or hungry. We evaluated young preterm infants’ spontaneous vocal production in non-painful contexts. We identified a vocal repertoire composed of nine types of vocalisations. High-pitched sounds were associated with relaxed postures, implying a positive valence, whereas long low-pitched vocalisations, associated more with grimaces and muscle tensions, appeared to have a more negative valence. Infants’ vocalisations were useful indicators of their internal state in two situations (when exposed to clothing constraints and environmental noises).     

Brain responses differ to faces of mothers and fathers

We encounter many faces each day but relatively few are personally familiar. Once faces are familiar, they evoke semantic and social information known about the person. Neuroimaging studies demonstrate differential brain activity to familiar and non-familiar faces; however, brain responses related to personally familiar faces have been more rarely studied. We examined brain activity with fMRI in adults in response to faces of their mothers and fathers compared to faces of celebrities and strangers. Overall, faces of mothers elicited more activity in core and extended brain regions associated with face processing, compared to fathers, celebrity or stranger faces. Fathers’ faces elicited activity in the caudate, a deep brain structure associated with feelings of love. These new findings of differential brain responses elicited by faces of mothers and fathers are consistent with psychological research on attachment, evident even during adulthood.     

Consistent witness responses: The effects of age and negative feedback

The effect of negative feedback in the absence of leading questions within a simulated forensic interview was investigated across young, middle-aged and older adults. Participants aged 18–82 (N = 101) watched a mock crime incident, were questioned, received feedback and re-questioned. It was hypothesised that when compared with neutral feedback, negative feedback would result in greater response changes and higher ratings of interview difficulty. The results supported this hypothesis and are consistent with Gudjonsson and Clark’s (1986) model of interrogative suggestibility. Correlation analysis revealed a significant negative association between age and response change following explicit negative feedback. Older adults showed reduced susceptibility to interrogative pressure.     

Measuring stress responses in postpartum mothers: perspectives from studies in human and animal populations

Reduced hypothalamic-pituitary-adrenal (HPA) responses to stress during the last week of pregnancy and lactation have been consistently observed in rat studies. Several contributing factors have been proposed for this phenomenon in lactation, including the suckling stimulus from the pups, hormones (oxytocin and prolactin) and opioids, a decrease in the ability of noradrenaline to potentiate hypothalamic responses and changes in pituitary responsiveness to ACTH secretagogues (AVP and CRF). In contrast to this vast literature using the rat model, only few studies have addressed this issue in the human population. The consensus is that women engaging in breastfeeding activities exhibit reduced anxiety, although the reductions in neuroendocrine and autonomic responses to stressors are variable, in part because of the different nature of the stressors used. Further work is required to investigate how additional factors, such as maternal parity or emotional salience of the stressor can affect stress responsiveness in postpartum women. Here, we review first the findings regarding stress responsiveness during lactation in both rat and human studies, and then discuss potential research avenues and methodological issues that could be the lead to future research protocols in human subjects. Knowing the reciprocal relationship in the mother-infant dyad, it is clear that investigation of the mechanisms regulating stress responses and mental health in postpartum mothers can only be beneficial to the development of the infant.     

Interactions between mothers and infants: impact of maternal anxiety

The aim of the study was to examine the impact of anxiety in the postnatal year on maternal contribution to mother-infant interaction. Participants were 32 mothers with high anxiety and 32 mothers with low anxiety, when their infants were aged 10-14 months. Mother-infant interaction was videotaped during a standardized play situation and coded blind to group status. High trait anxiety mothers showed less sensitive responsivity (p<.05) and reduced emotional tone (p<.05) during interaction. When participants scoring high in depressive symptomatology were removed for a subgroup analysis, the same pattern of results was obtained, suggesting that the observed differences in mother-infant interaction were due to group differences in anxiety.     

On the existence of prelinguistic categories: A case study

The purpose of this study was to investigate whether infants spontaneously form categories during the prelinguistic period and whether these categories are based on the same principles as adult basic-level categories. A new methodology, using a functional use measure as the determinant of category composition, was employed in a case study of one infant's horn category. Results indicated that this category met Schlesinger's (1982) criteria for a prelinguistic category and that the category was based on similarity relationships, as adult categories are.     

Attachment representations in mothers of preterm infants

The aim of the study was to assess attachment representations in mothers of preterm infants using the Working Model of Child Interview (WMCI) at the 12 months of the infant's corrected age. In addition, the relation between WMCI representation categories and the Edinburgh Postnatal Depression Scale score at 6 months of the infant's corrected age was studied. There were 38 mothers of preterm infants (<1500 g or <32 gestational weeks) and 45 mothers of full-term infants. The results showed no differences between the study groups in the distribution of the three main representation categories (balanced, disengaged and distorted). However, there were qualitative differences in representations between the groups. Furthermore, maternal depression symptoms were associated with distorted representation category. We suggest that despite the qualitative differences in the mothers’ representations, mothers of preterm infants are as likely to form balanced attachments with their infants as mothers of full-term infants.