Reasoning about a hidden object after a delay: evidence for robust representations in 5-month-old infants

The present research examined two alternative interpretations of violation-of-expectation findings that young infants can represent hidden objects. One interpretation is that, when watching an event in which an object becomes hidden behind another object, infants form a prediction about the event's outcome while both objects are still visible, and then check whether this prediction was accurate. The other interpretation is that infants' initial representations of hidden objects are weak and short-lived and as such sufficient for success in most violation-of-expectation tasks (as objects are typically hidden for only a few seconds at a time), but not more challenging tasks. Five-month-old infants succeeded in reasoning about the interaction of a visible and a hidden object even though (1) the two objects were never simultaneously visible, and (2) a 3- or 4-min delay preceded the test trials. These results provide evidence for robust representations of hidden objects in young infants.     

The role of surface discontinuity and shape in 4-month-old infants' object segregation

This research examined whether 4-month-old infants use a discontinuity in an object's front surface to visually segregate a display into two separate objects, and whether object shape enables its use. In Experiment 1, infants saw a three-dimensional display composed of two parts with distinctly different shapes. Two groups of infants saw a display in which these two shapes were divided by a visible discontinuity in the front surface (i.e., a boundary between the two objects). One of these groups saw the display move apart at the discontinuity when a gloved hand pulled one object; the second group saw the two objects move together as a single unit. A third group saw a modified version of this display that had no discontinuity present. The results suggested that infants regarded the discontinuity as an indication that the display could be composed of more than one object. In Experiment 2, infants saw the same display, but with a shape that did not highlight the discontinuity. The infants in this study showed no evidence of using the discontinuity. Together, the findings suggest that 4-month-old infants use the surface discontinuity between two objects as an indication that multiple objects could be present in a display, but only when scanning the outer edges of the display leads them to attend to it.     

Patterns of brain-electrical activity during declarative memory performance in 10-month-old infants

This study of infant declarative memory concurrently examined brain-electrical activity and deferred imitation performance in 10-month-old infants. Continuous electroencephalogram (EEG) measures were collected throughout the activity-matched baseline, encoding (modeling) and retrieval (delayed test) phases of a within-subjects deferred imitation task. Infants were divided into two memory performance groups based on the exhibition of ordered-recall after a 24-h delay. Whereas no group differences were found in EEG collected during encoding, performance-group differences in EEG were present during retrieval. Infants who successfully displayed ordered-recall showed a pattern of increasing EEG from baseline to task at anterior temporal scalp locations, whereas infants showing no ordered-recall displayed no changes in EEG from baseline to task. These findings are discussed with respect to the biobehavioral developments underlying declarative memory abilities.     

Play for Success: An intervention to boost object exploration in infants from low-income households

Infants from low-income households typically spend less time exploring objects and use less mature strategies when they do explore compared to their higher-income peers (e.g., Clearfield et al., 2014). The current study tested a novel intervention designed to boost early object exploration in infants from low-income households. The intervention, called Play for Success, was administered through the Early Head Start home visiting program, and asked all infants to explore a toy with a caregiver for 10 min a day every day for two weeks. Forty-two 6- to 10-month-old infants were randomly assigned to one of three intervention groups: Social (unstructured direction), Teach Two (simple structured direction), or Teach Many (complex structured direction). Infants’ exploratory behaviors were tested three times: before the intervention, immediately following, and again four weeks later. The results demonstrated that only infants in Teach 2 maintained their level of exploration at both the post-test and 4 weeks later while infants in the other groups showed significant decreases in exploration over time. These results suggest that Play for Success is a promising new intervention, but only in the condition that included repeated simple structured direction.     

The BDNFval66met polymorphism and individual differences in temperament in 4-month-old infants: A pilot study

Individual differences in infants’ temperament are under genetic control. We investigated the association between brain-derived-neurotrophic-factor (BDNF_val66met) polymorphism and temperament in 63 full-term infants. Met-carriers (N = 25) had lower Regulatory capacities compared to val-homozygotes (N = 38). These findings suggest that the BDNF polymorphism affects early temperament individual differences.     

Keeping track of locations during movement in 8- to 10-month-old infants

Infants of $\text{8}\text{1}\text{2}$ and $\text{9}\text{1}\text{2}$ mo of age were tested for the ability to “keep track,” i.e., to determine the location of an object hidden in one of two covered containers before their left-right positions were reversed. Infants in both age groups for whom the covers were the same color and younger infants for whom the covers were different colors were generally unable to keep track. Only the older infants provided with different colored covers were able to do so. An analysis which separated keeping track from the sensorimotor stage 4 error indicated that (a) there was no contingency between the two and (b) there were developmental differences in the nature of the error.     

Stability of deferred imitation in 12- to 18-month-old infants: A closer look into developmental dynamics

Deferred imitation is used to assess declarative memory in infants. Although a lot of studies show that infants from 6 months onwards are able to re-enact actions following a delay, only a few studies describe early declarative memory longitudinally. From a variable-centred approach, these studies found a modest relationship between measurement occasions that increases with age. However, no studies have analysed the differential aspect of memory development from a person-centred perspective. The present study analyses memory stabilities both from a variable-centred and person-centred approach within a sample of N = 87 infants of a 2-wave longitudinal design (12- and 18-month-olds). From a variable-centred perspective, the results indicate that, first, there was a significant increase in infants' memory performance and, second, that although reliable, the stability of infants' memory performance was relatively low. From a person-centred perspective two vs. three groups of infants were differentiated showing different developmental growth trajectories and stability correlations but no differences in language, cognitive and motor development. The implications of those results in terms of further test development are discussed. Furthermore, important methodological expansions for the analysis of infants' memory data are presented and discussed.     

Brain dynamics of visual anticipation during spatial occlusion tasks in expert tennis players

Stimulus identification and action outcome understanding for a rapid and accurate response selection, play a fundamental role in racquet sports. Here, we investigated the neurodynamics of visual anticipation in tennis manipulating the postural and kinematic information associated with the body of opponents by means of a spatial occlusion protocol. Event Related Potentials (ERPs) were evaluated in two groups of professional tennis players (N = 37) with different levels of expertise, while they observed pictures of opponents and predicted the landing position as fast and accurately as possible. The observed action was manipulated by deleting different body districts of the opponent (legs, ball, racket and arm, trunk). Full body image (no occlusion) was used as control condition. The worst accuracy and the slowest response time were observed in the occlusion of trunk and ball. The former was associated with a reduced amplitude of the ERP components likely linked to body processing (the N1 in the right hemisphere) and visual-motor integration awareness (the pP1), as well as with an increase of the late frontal negativity (the pN2), possibly reflecting an effort by the insula to recover and/or complete the most correct sensory-motor representation. In both occlusions, a decrease in the pP2 may reflect an impairment of decisional processes upon action execution following sensory evidence accumulation. Enhanced amplitude of the P3 and the pN2 components were found in more experienced players, suggesting a greater allocation of resources in the process connecting sensory encoding and response execution, and sensory-motor representation.     

Visual exploration of reaching space during left and right arm movements in 6-month-old infants

Infant's manual laterality and eye-hand coordination emerge during the second part of the first year of life with the development of reaching. Nevertheless, little is known about the potential asymmetric characteristics of this coordination. The aim of this study was to describe visuo-spatial exploration in 6-month-old infants during reaching, according to the hand used. More specifically, we examined if the use of the left or the right hand was linked to a specific type of visual exploration. Gaze direction during goal-directed reaching towards an object placed on the table was measured with a remote ASL 504 eye tracker (Bedford MA). Twelve babies aged 6 months were observed during six reaching sessions, alterning three sessions with an object on the left side of the subject and three with an object on the right side. Gaze direction and some hand variables (hand activity, hand opening and hand position from the body) were coded with The Observer software. Results showed that babies visually explore their reaching space differently according to the hand used: they look more at the object when they use their right hand and more around the object when they use their left hand; they also look more often at their left hand than at their right one. These results suggest that an asymmetric visuo-manual coordination exists as early as 6 months: vision seems to support (1) left hand during reaching for evaluate distances from object to baby by means of visual feedbacks and (2) right hand for identify what sort of object is. Results are discussed in light of manual specialization and specific hemispheric skills at this age.     

A community psychology of object meanings: Identity negotiation during disaster recovery

What do material goods intended for personal consumption mean to community? We use the extreme example of natural disaster recovery in a community to explore this question. Our work describes how members make sense of material objects that transition from private to public possessions (damaged goods) and public to private possessions (donated goods). By blending consumer and community psychology perspectives with our narratives, we employ a three-dimensional framework for analyzing object meanings: (1) material objects as agents of communitas (a shared sense of “we”), (2) material objects as agents of individualism (a focus on “me”), and (3) material objects as agents of opposition (the “we” that speaks for “me” and “us” versus “them”). This theoretical frame allows us to show how different conceptions of identity lead to conflicting meanings of objects within community, and to explain how and why object meanings shift as objects move across time and space from private to public and from scarcity to abundance. We also provide implications for coping with disasters that consider collective and individual identities as well as oppositional stances in between.     

The influence of attachment and temperament on venipuncture distress in 14-month-old infants: the Generation R Study

Objective

This study examined the effects of attachment and temperament on infant distress during venipuncture.

Method

The study was embedded in the Generation R Study, a prospective population-based study. Two different research procedures (i.e., blood sampling and the Ainsworth Strange Situation Procedure) yielded measures of venipuncture distress and attachment security and disorganization in 246 infants aged 14 months. Four temperament traits (distress to limitations, fear, recovery from distress, and sadness) were assessed using the maternally reported Infant Behavior Questionnaire - Revised, at the age of 6 months.

Results

There were no differences between mean levels of distress during venipuncture in infants classified as having insecure attachment, but there was a trend for disorganized attachment. The temperament traits were not related to distress. However, children with a disorganized attachment and higher temperamental fear had more venipuncture distress.

Conclusion

When different risk factors are present simultaneously, infant distress is heightened.     

The development of 3- to 9-month-old infants in two cultural contexts: Bayley longitudinal results for Cameroonian and German infants

Based on the Bayley Scales of Infant Development III, this study provides the results of a longitudinal study on the development of Cameroonian Nso farmer and German middle-class infants. Complete longitudinal data were available for 253 infants (69 from Cameroon and 184 from Germany) with Bayley assessments at 3, 6 and 9 months. The results show large differences between Cameroonian Nso and German infants with regard to gross motor and language development. The developmental sequence within each Bayley scale is more in line with the original Bayley sequence for German than for Cameroonian Nso infants as is indicated by Goodman scalogram analyses. Path analyses show some basic similarities between the developmental paths across ages for Cameroonian Nso and German infants, but more interconnections between the scales in the German sample. The results underline the need to adjust developmental scales to the cultural background of the infants to be tested.     

Attentional engagement during syllable discrimination: The role of salient prosodic cues in 6- to 8-month-old infants

Prosodic cues drive speech segmentation and guide syllable discrimination. However, less is known about the attentional mechanisms underlying an infant's ability to benefit from prosodic cues. This study investigated how 6- to 8-month-old Italian infants allocate their attention to strong vs. weak syllables after familiarization with four repeats of a single CV sequence with alternating strong and weak syllables (different syllables on each trial). In the discrimination test-phase, either the strong or the weak syllable was replaced by a pure tone matching the suprasegmental characteristics of the segmental syllable, i.e., duration, loudness and pitch, whereas the familiarized stimulus was presented as a control. By using an eye-tracker, attention deployment (fixation times) and cognitive resource allocation (pupil dilation) were measured under conditions of high and low saliency that corresponded to the strong and weak syllabic changes, respectively. Italian learning infants were found to look longer and also to show, through pupil dilation, more attention to changes in strong syllable replacement rather than weak syllable replacement, compared to the control condition. These data offer insights into the strategies used by infants to deploy their attention towards segmental units guided by salient prosodic cues, like the stress pattern of syllables, during speech segmentation.     

Neuromuscular control in individuals with chronic ankle instability: A comparison of unexpected and expected ankle inversion perturbations during a single leg drop-landing

While neuromuscular control deficits during inversion perturbations in chronic ankle instability (CAI) cohorts are well documented in the literature, anticipatory motor control strategies to inversion perturbations in CAI are largely unknown. The purpose of this study was to examine neuromuscular control and ankle kinematics in individuals with CAI (n = 15) and matched controls (n = 15) during unexpected and expected single leg drop-landings onto a tilted surface rotated 20° in the frontal plane. Muscle activity from 200 ms pre- to post-landing was recorded from the tibialis anterior (TA), medial gastrocnemius (MG), peroneus longus (PL) and peroneus brevis (PB). Mean muscle activity, co-contraction index (CCI), and peroneal latency was analyzed. Ankle inversion angle at initial contact, time to maximum inversion angle, maximum inversion angle and velocity were also assessed. Significantly longer PL latency, less time to maximum inversion and greater maximum inversion angle was found in CAI compared to controls. Regarding landing condition, significantly greater maximum inversion angle, less inversion at initial contact, longer PB latency, less TA activity and frontal plane CCI during the post-landing phase was found during the unexpected perturbation. Prolonged PL latency and altered ankle kinematics suggests reduced frontal plane ankle stabilization in CAI. However, similar motor control strategies were utilized in both groups during the ankle inversion perturbations.     

Destructive behavior increases as a function of reductions in alternative reinforcement during schedule thinning: A retrospective quantitative analysis

The behavioral processes determining the magnitude of the resurgence of destructive behavior during reinforcement schedule thinning have yet to be described, despite an uptick in prevalence research on the topic. As predicted by Resurgence as Choice theory, recent animal research has found that resurgence increases with the magnitude of a downshift in alternative reinforcement. Here we reanalyze the data from 2 recent prevalence studies to determine whether the size of the decrease in alternative reinforcement availability predicts the magnitude of resurgence in the clinic. Results from this retrospective analysis suggest that resurgence of destructive behavior increases significantly with decreases in the availability of alternative reinforcement. Implications for future research and translations of theoretical analyses to the clinic are discussed.     

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.     

创造性思维中语义搜索过程：基于答案累积时间函数和语义相似性的量化分析

通过描绘发散性思维测验(物品多用途, AUT)中答案生成在累积函数和语义相似性等一系列参数上的量化特征, 揭示创造性思维的语义搜索过程。结果发现：(1)新颖AUT条件中, 语义搜索呈现与自由联想类似的负加速特点, 但搜索速度较寻常AUT条件更慢。(2)新颖AUT条件中所生成的答案与题目(即物品)均具有较低的语义相似性, 且显著小于寻常AUT条件。(3)新颖AUT条件中生成的答案比寻常AUT条件表现出显著更低的聚类程度, 其中可聚类答案和未聚类答案与题目的语义相似度均较低, 且不存在显著差异, 二者在新颖性上也不存在显著差异。以上结果说明了创造性思维的语义信息搜索过程具有与自由联想类似的激活扩散特征, 但总体搜索速度较慢。新颖性要求使得个体在最初搜索时便开始摆脱题目的语义限制而进行远距离搜索(避免就近搜索), 并倾向于在每个语义场中只生成一个答案(避免局部搜索), 但也可能会在远离题目的语义场中生成多个同类别答案。     

Robustness of the rule-learning effect in 7-month-old infants: A close,multicenter replication of Marcus et al. (1999)

We conducted a close replication of the seminal work by Marcus and colleagues from 1999, which showed that after a brief auditory exposure phase, 7-month-old infants were able to learn and generalize a rule to novel syllables not previously present in the exposure phase. This work became the foundation for the theoretical framework by which we assume that infants are able to learn abstract representations and generalize linguistic rules. While some extensions on the original work have shown evidence of rule learning, the outcomes are mixed, and an exact replication of Marcus et al.'s study has thus far not been reported. A recent meta-analysis by Rabagliati and colleagues brings to light that the rule-learning effect depends on stimulus type (e.g., meaningfulness, speech vs. nonspeech) and is not as robust as often assumed. In light of the theoretical importance of the issue at stake, it is appropriate and necessary to assess the replicability and robustness of Marcus et al.'s findings. Here we have undertaken a replication across four labs with a large sample of 7-month-old infants (N = 96), using the same exposure patterns (ABA and ABB), methodology (Headturn Preference Paradigm), and original stimuli. As in the original study, we tested the hypothesis that infants are able to learn abstract “algebraic” rules and apply them to novel input. Our results did not replicate the original findings: infants showed no difference in looking time between test patterns consistent or inconsistent with the familiarization pattern they were exposed to.     

Robustness of the cognitive gains in 7-month-old bilingual infants: A close multi-center replication of Kovács and Mehler (2009)

We present an exact replication of Experiment 2 from Kovács and Mehler's 2009 study, which showed that 7-month-old infants who are raised bilingually exhibit a cognitive advantage. In the experiment, a sound cue, following an AAB or ABB pattern, predicted the appearance of a visual stimulus on the screen. The stimulus appeared on one side of the screen for nine trials and then switched to the other side. In the original experiment, both mono- and bilingual infants anticipated where the visual stimulus would appear during pre-switch trials. However, during post-switch trials, only bilingual children anticipated that the stimulus would appear on the other side of the screen. The authors took this as evidence of a cognitive advantage. Using the exact same materials in combination with novel analysis techniques (Bayesian analyses, mixed effects modeling and cluster based permutation analyses), we assessed the robustness of these findings in four babylabs (N = 98). Our results did not replicate the original findings: although anticipatory looks increased slightly during post-switch trials for both groups, bilingual infants were not better switchers than monolingual infants. After the original experiment, we presented additional trials to examine whether infants associated sound patterns with cued locations, for which we did not find any evidence either. The results highlight the importance of multicenter replications and more fine-grained statistical analyses to better understand child development.

Highlights

• We carried out an exact replication across four baby labs of the high-impact study by Kovács and Mehler (2009).
• We did not replicate the findings of the original study, calling into question the robustness of the claim that bilingual infants have enhanced cognitive abilities.
• After the original experiment, we presented additional trials to examine whether infants correctly associated sound patterns with cued locations, for which we did not find any evidence.
• The use of novel analysis techniques (Bayesian analyses, mixed effects modeling and cluster based permutation analyses) allowed us to draw better-informed conclusions.

     

The effects of massage velocity on heart rate and heart rate variability in healthy infants: A randomized crossover study

BackgroundInfant massage, in which mothers stroke their infant’s skin slowly and gently, can cause pleasant sensations in the infant that can be affected by the velocity of massage. However, the massage velocity at which infants feel the most pleasant sensations remains unclear.ObjectiveTo investigate the effects of massage velocity on heart rate (HR) and HR variability (HRV) in healthy infants.MethodTwenty-two infant-mother dyads two to seven months of age were recruited. Mothers stroked their infant’s skin at three massage velocities (5.0, 7.5, and 10.0 cm/s) in a randomized order for 15 min. The rhythm of massage velocity was calculated according to the length of three body areas. The massage velocity of the mothers was regulated using a metronome. HR and HRV (high frequency [HF] and low frequency [LF]) were measured at rest and during massage for each velocity. The effects on pleasantness were evaluated using percent change in median baseline value compared with median values for the three massage velocities. Statistical analysis was performed using analysis of variance mixed effect models to exclude “period” and “carryover” effects during massage.ResultsWhen measuring HF, massage (7.5 cm/s) caused a significant increase in pleasantness compared with 10.0 cm/s (p = 0.04). The HR and LF/HF ratio were not significantly changed between velocities.ConclusionResults of this study suggested that a massage velocity of 7.5 cm/s was the most pleasant for infants. Future research should investigate the relationship between an infant massage by optimal velocity and infant development in longitudinal studies.