Infants’ preference for prosocial behaviors: A literature review

In 2007, a study carried out by Hamlin, Wynn, and Bloom provided concrete evidence that infants as young as 6 months were capable of social evaluation, displaying an early preference for agents performing a prosocial behavior. Since then the development of early social abilities to judge other’s behavior has been the topic of a growing body of research. The present paper reviews studies conducted between 2007 and 2015 that experimentally examined infants’ social evaluation abilities by testing their preference for agents acting prosocially. We performed a detailed analysis of a corpus of 16 research studies including 59 experimental results, scrutinizing their methods and findings, and identifying their convergent and divergent features. This analysis showed that a preference for agents who perform prosocial behaviors (as opposed to antisocial or neutral) was present in a majority of infants, but some conflicting results have also been reported. The rich interpretation that infants are endowed with mature socio-moral evaluation abilities has not really been sufficiently discussed. In order to deepen this debate, we assessed other studies that have further explored infants’ understanding of the social value of behaviors. Many of the studies provide evidence that young infants manage to identify and prefer the prosocial agent by taking into account the context and agents' mental states beyond the behavior itself.In this study two specific areas are assessed: (1) studies that have previously explored social evaluation abilities beyond a basic preference for prosocial behavior and (2) current theories which attempt to explain how and why such preferences could exist so early in infancy. Future directions for research on social evaluation abilities in infants are also discussed as well as a review of the literature.     

6- to 9-Month old infants discriminate vowel durations in variable speech contexts

Discriminating temporal relationships in speech is crucial for speech and language development. However, temporal variation of vowels is difficult to perceive for young infants when it is determined by surrounding speech sounds. Using a familiarization-discrimination paradigm, we show that English-learning 6- to 9-month-olds are capable of discriminating non-native acoustic vowel duration differences that systematically vary with subsequent consonantal durations. Furthermore, temporal regularity of stimulus presentation potentially makes the task easier for infants. These findings show that young infants can process fine-grained temporal aspects of speech sounds, a capacity that lays the foundation for building a phonological system of their ambient language(s).     

Baby babbling at five months linked to sex hormone levels in early infancy

Gender-dependent differentiation of the brain at morphological, neurochemical and functional levels of organization have been shown to be primarily controlled by sex differences in gonadal hormone concentrations during pre- and early postnatal development. Indeed, previous studies have reported that pre- and perinatal hormonal environments influence brain development and, consequently, affect sex specific long-term language outcomes.Herein, we investigated whether postnatal surges of estrogen (estradiol) and androgen (testosterone) may predict properties of pre-speech babbling at five months. This study is the first attempt to investigate a possible correlation between sex hormones and infants’ articulatory skills during the typical postnatal period of extended hormonal activity known as ‘mini-puberty.’ A hierarchical, multiple regression approach revealed a significant, robust positive relationship between 4-week concentrations of estradiol and individual articulatory skills. In contrast, testosterone concentrations at five months negatively correlated with articulatory skills at the same age in both boys and girls. Our findings reinforce the assumption of the importance of sex hormones for auditory–vocal development towards language in human infants.     

Associations between touchscreen exposure and hot and cool inhibitory control in 10-month-old infants

Touchscreen use amongst young children has proliferated in recent years, yet little is known about the association between daily touchscreen exposure and inhibitory control in the first year of life. Previous research has found a negative association between the amount of television viewing and inhibitory control in early childhood, but it is unclear whether negative associations with screen use extend to touchscreens. The current study presents an exploratory analysis of the cross-sectional associations between inhibitory control and the amount of touchscreen use amongst 10-month-olds (n = 128–156). Touchscreen exposure was assessed via parent-report. In order to include a range of “hot” and “cool” aspects of inhibitory control, these skills were assessed using lab-based response inhibition and prohibition tasks as well as parent-reported observations of infants’ inhibitory control abilities and broader regulatory behaviors. A “Cognitive Executive Function (EEFQ-CEF)” score (encompassing Inhibitory Control, Flexibility, and Working Memory items) was included as a secondary broader executive function construct to examine whether effects showed specificity to inhibitory control rather than executive functions more generally. Correlation analyses indicated no association between touchscreen exposure and the four indices of IC. However, a positive association was found for the amount of touchscreen exposure and EEFQ-CEF once accounting for sociodemographic variables. The implications of these findings and future directions are discussed.     

Binocular vision in infancy: Responsiveness to uncrossed horizontal disparity

This research explored the onset of stereopsis, the ability to perceive depth from the different views provided by the two eyes. In a longitudinal study, infants were tested weekly from 6 to 20 weeks of age. The primary goal of the study was to establish the onset and the early development of sensitivity to uncrossed horizontal disparity. The infant participants were shown dynamic random dot stereograms displaying two squares, one with uncrossed horizontal disparity (0.5°) and one with vertical disparity (0.5°). The stimuli were presented on an autostereoscopic monitor. We used two methods, the forced-choice preferential looking (FPL) method and the classical natural preference (CNP) method, to measure whether the infants preferred the uncrossed over the vertical disparity display. According to the FPL data, the mean relative preferences for horizontal over vertical disparity were significantly greater than chance probability (0.50) from 13 weeks of age onward. With the CNP method we found significant preferences for uncrossed horizontal disparity from 15 weeks onward. The FPL method was hence more sensitive than the CNP method as it indicated an earlier onset of responsiveness to stereoscopic information.     

The Gender Congruence and Life Satisfaction Scale (GCLS): Development and validation of a scale to measure outcomes from transgender health services

Background: It is vital that the treatment offered at transgender health services can be evaluated to ensure a high quality of care. However, the tools currently used to evaluate treatment at transgender health services are limited by mainly focusing on mental health or because they have been developed for binary transgender people only. This study therefore aimed to develop and validate a tool that addresses these limitations. The Gender Congruence and Life Satisfaction Scale (GCLS) was developed through reviewing the literature, conducting interviews with transgender people, and holding discussions with experts working in transgender healthcare. An initial pool of items was developed and feedback on these was obtained. The tool was then validated.

Method: For the validation of the tool, a total of 789 participants (451 transgender [171 transgender females, 147 transgender males, 133 people identifying as non-binary], and 338 cisgender [254 females, 84 males]) were recruited from the United Kingdom to test the factor structure and validity of the GCLS.

Results: Exploratory factor analysis retained 38 items which formed seven subscales (psychological functioning; genitalia; social gender role recognition; physical and emotional intimacy; chest; other secondary sex characteristics; and life satisfaction). These seven subscales were found to have good internal consistency and convergent validity. The GCLS was also found to be capable of discriminating between groups (e.g., people who have and have not undergone gender affirming medical interventions). Transgender and cisgender subscale norms are provided for the GCLS.

Conclusion: The GCLS is a suitable tool to use with the transgender population to measure health-related outcomes for both clinical and research purposes.     

Are babies sensitive to the context of acute pain episodes? Infant distress and maternal soothing during immunization routines at 3 and 5 months of age

Ninety‐three healthy full‐term Italian infants were observed longitudinally at 3 and 5 months during routine vaccinations. Mothers' behaviour was also observed. Participants were divided into two cohorts depending on procedure of inoculation (the first cohort, n=44, showed more distress; the second cohort, n=49, showed less distress). Results indicate that babies' different levels of behavioural distress correspond to mothers' different soothing strategies. Maternal proximal soothing at 3 months predicts faster infant quieting at 5 months, but concurrent and predictive effects of maternal proximity are apparent only when level of baby distress is not too high. The study confirms the view that young babies are sensitive to the overall context of acute pain episodes, including medical procedure and maternal soothing. Copyright © 2005 John Wiley & Sons, Ltd.     

Bare fingers,but no obvious influence of “prickly” Velcro! In the absence of parents’ encouragement,it is not clear that “sticky mittens” provide an advantage to the process of learning to reach

In their critique of our mittens study, Needham et al. (2015. Infant Behavior and Development) describe our findings as “surprising.” Further; they suggest that babies in our “sticky mittens” condition may have been discouraged from reaching because, in our study, infants may have touched “prickly” Velcro with their bare fingers. In this response, we present data analyses that do not support the interpretation that finger contact with our Velcroed toy surfaces was associated with poor reaching performance in our “sticky” mittens group. We also clarify that our toys were mainly covered with “non-prickly” Velcro. To explain discrepancies between studies, we restate the original intent of our study and reasons for our methodological modifications. We point to confounds and lack of critical control conditions in the Needham et al. studies, which prevent the making of firm inferences about the effectiveness of the “sticky mittens experience” on the learning to reach process. We also present additional analyses on our “sticky” mittens group showing that the increasing rate of finger touch on the toy leads to greater reaching performance while the rate of toy sticking to the mittens does not. We discuss the importance of sensory-motor experience on the development of learning to reach in infancy and conclude that our results are not surprising.     

Leveraging epigenetics to examine differences in developmental trajectories of social attention: A proof-of-principle study of DNA methylation in infants with older siblings with autism

Preliminary evidence suggests that changes in DNA methylation, a widely studied epigenetic mechanism, contribute to the etiology of Autism Spectrum Disorder (ASD). However, data is primarily derived from post-mortem brain samples or peripheral tissue from adults. Deep-phenotyped longitudinal infant cohorts are essential to understand how epigenetic modifications relate to early developmental trajectories and emergence of ASD symptoms. We present a proof-of-principle study designed to evaluate the potential of prospective epigenetic studies of infant siblings of children with ASD.Illumina genome-wide 450 K DNA methylation data from buccal swabs was generated for 63 male infants at multiple time-points from 8 months to 2 years of age (total N = 107 samples). 11 of those infants received a diagnosis of ASD at 3 years. We conducted a series of analyses to characterize DNA methylation signatures associated with categorical outcome and neurocognitive measures from parent-report questionnaire, eye-tracking and electro-encephalography.Effects observed across the entire genome (epigenome-wide association analyses) suggest that collecting DNA methylation samples within infant-sibling designs allows for the detection of meaningful signals with smaller sample sizes than previously estimated. Mapping networks of co-methylated probes associated with neural correlates of social attention implicated enrichment of pathways involved in brain development. Longitudinal modelling found covariation between phenotypic traits and DNA methylation levels in the proximity of genes previously associated with cognitive development, although larger samples and more complete datasets are needed to obtain generalizable results.In conclusion, assessment of DNA methylation profiles at multiple time-points in infant-sibling designs is a promising avenue to comprehend developmental origins and mechanisms of ASD.