Individual differences in processing speed and curiosity explain infant habituation and dishabituation performance.

Habituation and dishabituation are the most prevalent measures of infant cognitive functioning, and they have reliably been shown to predict later cognitive outcomes. Yet, the exact mechanisms underlying infant habituation and dishabituation are still unclear. To investigate them, we tested 106 8-month-old infants on a classic habituation task and a novel visual learning task. We used a hierarchical Bayesian model to identify individual differences in sustained attention, learning performance, processing speed and curiosity from the visual learning task. These factors were then related to habituation and dishabituation. We found that habituation time was related to individual differences in processing speed, while dishabituation was related to curiosity, but only for infants who did not habituate. These results offer novel insights in the mechanisms underlying habituation and serve as proof of concept for hierarchical models as an effective tool to measure individual differences in infant cognitive functioning. RESEARCH HIGHLIGHTS: We used a hierarchical Bayesian model to measure individual differences in infants' processing speed, learning performance, sustained attention, and curiosity. Faster processing speed was related to shorter habituation time. High curiosity was related to stronger dishabituation responses, but only for infants who did not habituate.

Preterm Birth and Other Measures of Infant Biological Vulnerability: Associations with Maternal Sensitivity and Infant Cognitive Development.

INTRODUCTION: Low birth weight (LBW), biological vulnerability that includes preterm birth (PTB) and small for gestational age (SGA), is associated with reduced maternal sensitivity ("making accurate inferences about an infant's physical and emotional needs and responding appropriately") and impaired infant cognitive development. However, research does not examine if preterm birth, SGA, or both drive these associations. This study separated these measures of biological vulnerability to examine associations of LBW, PTB, and SGA with maternal sensitivity and infant cognitive development (controlling for maternal depression, breastfeeding, and demographic covariates). METHODS: The sample included 6900 9-month-old infants from the Early Childhood Longitudinal Study-Birth Cohort and used birth certificate data, maternal interviews, assessments of maternal sensitivity and infant cognitive development. Multiple linear regressions examined LBW, PTB, and SGA associations with concurrent measures of maternal sensitivity and infant cognition. RESULTS: Of the biological vulnerabilities, preterm birth had the strongest negative association with maternal sensitivity (F1,6450 = 29.48 versus 15.33 and 5.51, ps < .001) and infant cognitive development (F1,6450) = 390.65 versus 248.02 and 14.43, ps < .001). In the final regression model, preterm birth and maternal sensitivity were uniquely associated with infant cognitive development (R2 = .05, p < .001), after controlling for maternal depression, breastfeeding, and demographics. CONCLUSION: In this nationally representative infant sample infants, PTB had a stronger negative association with both maternal sensitivity and infant cognitive development in comparison to SGA or LBW. The LBW designation combines infants born preterm with SGA infants, potentially minimizing differences in developmental outcomes of PTB and SGA infants.

High quality social environment buffers infants' cognitive development from poor maternal mental health: Evidence from a study in Bhutan.

Poor maternal mental health negatively impacts cognitive development from infancy to childhood, affecting both behavior and brain architecture. In a non-western context (Thimphu, Bhutan), we demonstrate that culturally-moderated factors such as family, community social support, and enrichment may buffer and scaffold the development of infant cognition when maternal mental health is poor. We used eye-tracking to measure early building blocks of cognition: attention regulation and social perception, in 9-month-old Bhutanese infants (N = 121). The cognitive development of Bhutanese infants in richer social environments was buffered from poor maternal mental health, while for infants in environments with lower rates of protective social environment factors, worse maternal mental health significantly predicted greater costs for infant attention, a fundamental building block cognition. International policies and interventions geared to improve maternal mental health and child health outcomes should incorporate each regions' unique family, cultural, and community support structures.

Longitudinal infant fNIRS channel-space analyses are robust to variability parameters at the group-level: An image reconstruction investigation.

The first 1000 days from conception to two-years of age are a critical period in brain development, and there is an increasing drive for developing technologies to help advance our understanding of neurodevelopmental processes during this time. Functional near-infrared spectroscopy (fNIRS) has enabled longitudinal infant brain function to be studied in a multitude of settings. Conventional fNIRS analyses tend to occur in the channel-space, where data from equivalent channels across individuals are combined, which implicitly assumes that head size and source-detector positions (i.e. array position) on the scalp are constant across individuals. The validity of such assumptions in longitudinal infant fNIRS analyses, where head growth is most rapid, has not previously been investigated. We employed an image reconstruction approach to analyse fNIRS data collected from a longitudinal cohort of infants in The Gambia aged 5- to 12-months. This enabled us to investigate the effect of variability in both head size and array position on the anatomical and statistical inferences drawn from the data at both the group- and the individual-level. We also sought to investigate the impact of group size on inferences drawn from the data. We found that variability in array position was the driving factor between differing inferences drawn from the data at both the individual- and group-level, but its effect was weakened as group size increased towards the full cohort size (N = 53 at 5-months, N = 40 at 8-months and N = 45 at 12-months). We conclude that, at the group sizes in our dataset, group-level channel-space analysis of longitudinal infant fNIRS data is robust to assumptions about head size and array position given the variability in these parameters in our dataset. These findings support a more widespread use of image reconstruction techniques in longitudinal infant fNIRS studies.

Functional imaging of the developing brain with wearable high-density diffuse optical tomography: A new benchmark for infant neuroimaging outside the scanner environment.

Studies of cortical function in the awake infant are extremely challenging to undertake with traditional neuroimaging approaches. Partly in response to this challenge, functional near-infrared spectroscopy (fNIRS) has become increasingly common in developmental neuroscience, but has significant limitations including resolution, spatial specificity and ergonomics. In adults, high-density arrays of near-infrared sources and detectors have recently been shown to yield dramatic improvements in spatial resolution and specificity when compared to typical fNIRS approaches. However, most existing fNIRS devices only permit the acquisition of ~20-100 sparsely distributed fNIRS channels, and increasing the number of optodes presents significant mechanical challenges, particularly for infant applications. A new generation of wearable, modular, high-density diffuse optical tomography (HD-DOT) technologies has recently emerged that overcomes many of the limitations of traditional, fibre-based and low-density fNIRS measurements. Driven by the development of this new technology, we have undertaken the first study of the infant brain using wearable HD-DOT. Using a well-established social stimulus paradigm, and combining this new imaging technology with advances in cap design and spatial registration, we show that it is now possible to obtain high-quality, functional images of the infant brain with minimal constraints on either the environment or on the infant participants. Our results are consistent with prior low-density fNIRS measures based on similar paradigms, but demonstrate superior spatial localization, improved depth specificity, higher SNR and a dramatic improvement in the consistency of the responses across participants. Our data retention rates also demonstrate that this new generation of wearable technology is well tolerated by the infant population.

Mapping cortical rhythms to infant behavioral tendencies via baseline EEG and parent-report.

An important goal of developmental science is to understand how the early organization of the brain and behavioral tendencies are interconnected. A foundational step in pursuit of this goal is to identify brain-behavior relations. Much progress has been made identifying such relations during infancy by linking baseline electroencephalography (EEG) activity to infants' performance in lab-based measures of socio-emotional and cognitive development. Parent-report represents another resource in expanding our understanding to infants' behavioral tendencies in their natural environment. The current study explored how parent-report of 6- to 12-month-old (N = 53) infants' attention and regulatory abilities relates to cortical activity. The results confirmed one key hypothesis that lower levels of theta and higher levels of beta and gamma over the frontal region would be related to infants' attentional abilities. These results are consistent with the extant baseline EEG literature. Cuddliness was robustly related to higher levels of theta and lower levels of beta over the posterior, likely reflecting infants' tendency to use another person to self-regulate. Our results indicate links between these cortical rhythms and attention and regulatory processes have infant origins. Our results indicate furture research investigating brain-behavior relations using parent-report is warranted.

Neural signatures for sustaining object representations attributed to others in preverbal human infants.

A major feat of social beings is to encode what their conspecifics see, know or believe. While various non-human animals show precursors of these abilities, humans perform uniquely sophisticated inferences about other people's mental states. However, it is still unclear how these possibly human-specific capacities develop and whether preverbal infants, similarly to adults, form representations of other agents' mental states, specifically metarepresentations. We explored the neurocognitive bases of eight-month-olds' ability to encode the world from another person's perspective, using gamma-band electroencephalographic activity over the temporal lobes, an established neural signature for sustained object representation after occlusion. We observed such gamma-band activity when an object was occluded from the infants' perspective, as well as when it was occluded only from the other person (study 1), and also when subsequently the object disappeared, but the person falsely believed the object to be present (study 2). These findings suggest that the cognitive systems involved in representing the world from infants' own perspective are also recruited for encoding others' beliefs. Such results point to an early-developing, powerful apparatus suitable to deal with multiple concurrent representations, and suggest that infants can have a metarepresentational understanding of other minds even before the onset of language.

Minding the gap: a sex difference in young infants' mental rotation through thirty degrees of arc.

Mental rotation (MR) is an important feature of spatial cognition invoking mental imagery of an object's appearance when viewed from a new orientation. Prior studies have revealed evidence of MR in infants, including a sex difference similar to that detected in older populations. Some of these studies used visual habituation methods whereby infants were familiarized with an object rotating through a 240° angle, followed by test trials showing either the habituation object or a mirror image object rotating through the previously unseen 120° angle. Significantly longer looking at either of these objects was taken to reflect infants' ability to recognize the habituation object even when seen from a novel viewpoint, suggesting the capacity for MR. However, these infants' responses could, in theory, be explained with reference to perceptual discrimination rather than MR, because the views of the habituation and test objects were very similar in some video frames. In the current study, we observed a diverse population of 5-month-olds (24 females, 24 males) for evidence of MR through 30° of arc. In this more challenging test, our stimuli left a 30° gap angle between critical video frames representing the habituation and test objects. Consistent with earlier reports, we found that relative to female infants, male infants looked significantly longer at the mirror image test stimulus immediately following habituation. These results add to an emerging consensus that some young infants are capable of MR, and that male and female infants on average behave differently in this type of MR task.

Mother-infant self- and interactive contingency at four months and infant cognition at one year: A view from microanalysis.

Although a considerable literature documents associations between early mother-infant interaction and cognitive outcomes in the first years of life, few studies examine the contributions of contingently coordinated mother-infant interaction to infant cognitive development. This study examined associations between the temporal dynamics of the contingent coordination of mother-infant face-to-face interaction at 4 months and cognitive performance on the Bayley Scales of Infant Development at age one year in a sample of (N = 100) Latina mother-infant pairs. Split-screen videotaped interactions were coded on a one second time base for the communication modalities of infant and mother gaze and facial affect, infant vocal affect, and mother touch. Multi-level time-series models evaluated self- and interactive contingent processes in these modalities and revealed 4-month patterns of interaction associated with higher one-year cognitive performance, not identified in prior studies. Infant and mother self-contingency, the moment-to-moment probability that the individual's prior behavior predicts the individual's future behavior, was the most robust measure associated with infant cognitive performance. Self-contingency findings showed that more varying infant behavior was optimal for higher infant cognitive performance, namely, greater modulation of negative affect; more stable maternal behavior was optimal for higher infant cognitive performance, namely, greater likelihood of sustaining positive facial affect. Although interactive contingency findings were sparse, they showed that, when mothers looked away, or dampened their faces to interest or mild negative facial affect, infants with higher 12-month cognitive performance were less likely to show negative vocal affect. We suggest that infant ability to modulate negative affect, and maternal ability to sustain positive affect, may be mutually reinforcing, together creating a dyadic climate that is associated with more optimal infant cognitive development.

The sound of silence: Reconsidering infants' object categorization in silence, with labels, and with nonlinguistic sounds.

A large body of research based on a specific stimulus set (dinosaur/fish) has argued that auditory labels and novel communicative signals (such as beeps used in a communicative context) facilitate category formation in infants, that such effects can be attributed to the auditory signals' communicative nature, and that other auditory stimuli have no effect on categorization. A contrasting view, the auditory overshadowing hypothesis, maintains that auditory signals disrupt processing of visual information and, therefore, interfere with categorization, with more unfamiliar sounds having a more disruptive effect than familiar ones. Here, we used the dinosaur/fish stimulus set to test these contrasting theories in two experiments. In Experiment 1 (N = 17), we found that 6-month-old infants were able to form categories of these stimuli in silence, weakening the claim that labels facilitated their categorization in infants. These results imply that prior findings of no categorization of these stimuli in the presence of nonlinguistic sounds must be due to disruptive effects of such sounds. In Experiment 2 (N = 17), we showed that familiarity modulated the disruptive effect of nonlinguistic sounds on infants' categorization of these stimuli. Together, these results support the auditory overshadowing hypothesis and provide new insights into the interaction between visual and auditory information in infants' category formation.

Associations of human milk oligosaccharides and bioactive proteins with infant growth and development among Malawian mother-infant dyads.

BACKGROUND: Human milk oligosaccharides (HMOs) and bioactive breast milk proteins have many beneficial properties. Information is sparse regarding associations between these milk constituents and infant growth and development in lower-income countries. OBJECTIVES: We aimed to examine associations of milk content of HMOs and bioactive proteins at 6 mo postpartum with infant growth and motor and cognitive development. These are secondary analyses of a randomized controlled trial in rural Malawi. METHODS: Breast milk samples were analyzed at 6 mo (n = 659) for general categories of HMOs (total HMOs, fucosylated HMOs, and sialylated HMOs), 51 individual HMOs, and 6 bioactive proteins (lactalbumin, lactoferrin, lysozyme, antitrypsin, IgA, and osteopontin). We examined associations of the relative abundances of HMOs and concentrations of bioactive proteins with infant growth from 6 to 12 mo [change in length-for-age (ΔLAZ), weight-for-age, weight-for-length, and head circumference z-scores] as well as ability to stand or walk alone at 12 mo, and motor and language skills, socioemotional development, executive function, and working memory at 18 mo. Analyses were adjusted for covariates and multiple hypothesis testing. RESULTS: Among all participants, there were inverse associations of IgA and lactoferrin concentrations with motor skills (P = 0.018 and P = 0.044), and a positive association of lactalbumin concentration with motor skills (P = 0.038). Among secretors only [fucosyltransferase 2 gene (FUT2) positive], there were positive associations of absolute abundance of HMOs with ΔLAZ (P = 0.035), and relative abundance of fucosylated and sialylated HMOs with language at 18 mo (P < 0.001 and P = 0.033, respectively), and inverse associations of osteopontin with standing and walking at 12 mo (P = 0.007 and 0.002, respectively). Relative abundances of several individual HMOs were associated with growth and development, mostly among secretors. CONCLUSIONS: Certain bioactive breast milk proteins and HMOs are associated with infant growth and motor and cognitive development. Further studies are needed to determine if a causal relation exists.This trial was registered at clinicaltrials.gov as NCT01239693.

The development of mental rotation ability across the first year after birth.

Mental rotation (MR) is the ability to imagine the appearance of an object from a different perspective. This ability is involved in many human cognitive and behavioral activities. We discuss studies that have examined MR in infants and its development across the first year after birth. Despite some conflicting findings across these studies, several conclusions can be reached. First, MR may be available to human infants as young as 3 months of age. Second, MR processes in infancy may be similar or identical to MR processes later in life. Third, there may be sex differences in MR performance, in general favoring males. Fourth, there appear to be multiple influences on infants' MR performance, including infants' motor activity, stimulus complexity, hormones, and parental attitudes. We conclude by calling for additional research to examine more carefully the causes and consequences of MR abilities early in life.

Thiamine dose response in human milk with supplementation among lactating women in Cambodia: study protocol for a double-blind, four-parallel arm randomised controlled trial.

INTRODUCTION: Thiamine (vitamin B1) deficiency remains a concern in Cambodia where women with low thiamine intake produce thiamine-poor milk, putting their breastfed infants at risk of impaired cognitive development and potentially fatal infantile beriberi. Thiamine fortification of salt is a potentially low-cost, passive means of combating thiamine deficiency; however, both the dose of thiamine required to optimise milk thiamine concentrations as well as usual salt intake of lactating women are unknown. METHODS AND ANALYSIS: In this community-based randomised controlled trial, 320 lactating women from Kampong Thom, Cambodia will be randomised to one of four groups to consume one capsule daily containing 0, 1.2, 2.4 or 10 mg thiamine as thiamine hydrochloride, between 2 and 24 weeks postnatal. The primary objective is to estimate the dose where additional maternal intake of thiamine no longer meaningfully increases infant thiamine diphosphate concentrations 24 weeks postnatally. At 2, 12 and 24 weeks, we will collect sociodemographic, nutrition and health information, a battery of cognitive assessments, maternal (2 and 24 weeks) and infant (24 weeks only) venous blood samples (biomarkers: ThDP and transketolase activity) and human milk samples (also at 4 weeks; biomarker: milk thiamine concentrations). All participants and their families will consume study-provided salt ad libitum throughout the trial, and we will measure salt disappearance each fortnight. Repeat weighed salt intakes and urinary sodium concentrations will be measured among a subset of 100 participants. Parameters of Emax dose-response curves will be estimated using non-linear least squares models with both 'intention to treat' and a secondary 'per-protocol' (capsule compliance ≥80%) analyses. ETHICS AND DISSEMINATION: Ethical approval was obtained in Cambodia (National Ethics Committee for Health Research 112/250NECHR), Canada (Mount Saint Vincent University Research Ethics Board 2017-141) and the USA (University of Oregon Institutional Review Board 07052018.008). Results will be shared with participants' communities, as well as relevant government and scientific stakeholders via presentations, academic manuscripts and consultations. TRIAL REGISTRATION NUMBER: NCT03616288.

Voulez-vous jouer avec moi? Twelve-month-olds understand that foreign languages can communicate.

Infants understand that speech in their native language allows speakers to communicate. Is this understanding limited to their native language or does it extend to non-native languages with which infants have no experience? Twelve-month-old infants saw an actor, the Communicator, repeatedly select one of two objects. When the Communicator could no longer reach the target but a Recipient could, the Communicator vocalized a nonsense phrase either in English (infants' native language), Spanish (rhythmically different), or Russian (phonotactically different), or hummed (a non-speech vocalization). Across all three languages, native and non-native, but not humming, infants looked longer when the Recipient gave the Communicator the non-target object. Although, by 12 months, infants do not readily map non-native words to objects or discriminate most non-native speech contrasts, they understand that non-native languages can transfer information to others. Understanding language as a tool for communication extends beyond infants' native language: By 12 months, infants view language as a universal mechanism for transferring and acquiring new information.

A Plea for Scientific Ambitions: Reply to Commentaries from Martin Wieser, Nikolai Veresov, Asger Neumann, and Peter Krøjgaard.

The paper is a reply to commentaries to "Activity theories and the Ontology of Psychology: Learning from Danish and Russian Experiences" (Mammen and Mironenko 2015). At the same time it is an attempt to reply to more general issues raised by the commentators and an attempt to further develop some general ideas from our paper with a focus on the introduction of the new analytical concepts sense and choice categories. These concepts have been elaborated in an axiomatic frame in (Mammen 2016) and the present paper is thus also pointing forwards to that and supporting it with examples from research on adult human relations of love and affection and on infant cognitive development. A few examples from myth and literature are referred to also. The ambition is to introduce new analytical tools across schools and domains of psychology which open for theoretical inclusion of new phenomena and re-structuring of well-known ones. The hope is to surmount some problems, as e.g. the dilemma between dualism and reductionism, which have been obstacles in the search for conceptual and methodological coherence in psychology. In the first place the hope is also to sharpen the analytical, critical and practical potential of psychology as a science. The ambition is not, here and now, to develop a comprehensive general theory as a container for the huge amount of empirical results collected using very heterogeneous criteria for what belongs to the domain of psychology and very heterogeneous conceptual frames. Here we still need some patience following the lesson from natural science, step by step including new domains as the conceptual and practical frames are expanding, but on the other hand not excluding anything apriori.