Design Choices in the Infant Habituation Paradigm: A Pre-registered Crowd-Sourced Systematic Review and Meta-Analysis

Methodological variations and inconsistency in reporting practices pose considerable challenges to the interpretation and generalizability of outcomes derived from the habituation paradigm - one of the most prominent methods for studying infant cognition. In a systematic review, we map out experimental design choices in habituation study samples aged 0-18 months using looking time measures. 2,853 records published in peer-reviewed journals between 2000-2019 were extracted from PsycInfo and Web of Science. 785 (27.5%) papers were identified after screening (Fleiss kappa = .60, 95%, CI[.40 - .80], 6 blind raters). We adopt a collaborative, multi-lab approach for crowd-sourced data collection involving raters from the developmental research community. In a meta-analysis, we assess the impact of habituation detection criteria on the novelty effect size, moderated by age. Our results will inform a detailed evaluation of experimental designs and a set of specific guidelines to improve research and reporting practices in infant habituation research.

Some notes on Mindsponge in infant cognition

I noted some thoughts on applying Mindsponge framework to some issues in infant cognition.

Birdsong fails to support object categorization in human infants

Recent evidence reveals a precocious link between language and cognition in human infants: listening to their native language supports infants’ core cognitive processes, including object categorization, and does so in a way that other acoustic signals (e.g., time-reversed speech; sine-wave tone sequences) do not. Moreover, language is not the only signal that confers this cognitive advantage: listening to vocalizations of non-human primates also supports object categorization in 3- and 4-month-olds. Here, we move beyond primate vocalizations to clarify the breadth of acoustic signals that promote infant cognition. We ask whether listening to birdsong, another naturally produced animal vocalization, also supports object categorization in 3- and 4-month-old infants. We report that listening to zebra finch song failed to confer a cognitive advantage. This outcome brings us closer to identifying a boundary condition on the range of non-linguistic acoustic signals that initially support infant cognition.

A Fine-Tooth Comb for Measurement Reliability: Predicting True Score and Error Variance in Hierarchical Models

The primary objective of this work is to extend classical test theory (CTT), in particular, forthe case of repeated measurement studies. The guiding idea that motivates this work is that anytheory ought to be expanded when it is not compatible with commonly observed phenomena-namely, that homogeneous variance components appear to be the exception and not the rule inpsychological applications. Additionally, advancements in methodology should also be consideredin light of theory expansion, when appropriate. We argue both goals can be accomplishedby merging heterogeneous variance modeling with the central tenants of CTT. To this end, weintroduce novel methodology that is based on the mixed-effects location scale model. This allows for fitting explanatory models to the true score (between-group) and error (within-group)variance. Two illustrative examples, that span from educational research to infant cognition,highlight such possibilities. The results revealed that there can be substantial individual differences in error variance, which necessarily implies the same for reliability, and that true scorevariance can be a function of covariates. We incorporate this variance heterogeneity into novel reliability indices that can be used to forecast group or person-specific reliability. These extend traditional formulations that assume the variance components are homogeneous. This powerful approach can be used to identify predictors of true score and error variance, which can then be used to refine measurement. The methods are implemented in the user-friendly R packageICCier.

Simplicity and validity in infant research

Infancy researchers have often drawn rich conclusions about early capacities to understand abstract concepts like "causality" or "prosociality" from infants' responses to highly simplified and artificial stimuli, leading to questions about the validity of studies utilizing these methods. Indeed, do these stimuli effectively illustrate abstract concepts to infant participants? And if they do, why not assess infants’ cognitive capacities using ecologically valid stimuli of the sort that infants encounter in their everyday lives? Here, using examples from infant cognitive and social developmental research, we make explicit the underlying logic of using simplified stimuli in studies with infant populations by discussing the tradeoff infancy researchers are forced to make between measurement validity and ecological validity. Though we agree that concerns about the validity of simplified stimuli that emerge from this trade-off are founded, we argue that results from these studies should not be dismissed purely on ecological grounds. Rather, we present guidelines for productively challenging the validity of infant research in ways that further our understanding of infant cognition.

Associations of maternal fructose and sugar-sweetened beverage and juice intake during lactation with infant neurodevelopmental outcomes at 24 months

ABSTRACT Background Our prior studies revealed that infant somatic growth is influenced by fructose in breast milk, and fructose in breast milk is increased in response to maternal sugar-sweetened beverage (SSB) intake in lactation. It is unknown whether infant neurodevelopmental outcomes are also influenced by maternal SSBs in lactation. Objectives To determine whether infant cognitive development at 24 postnatal months was influenced by maternal fructose consumption during lactation, and whether this relation persisted after accounting for maternal SSB and juice (SSB + J) intake. Methods Hispanic mother–infant pairs (n = 88) were recruited across the spectrum of prepregnancy BMI. Mothers completed two 24-h dietary recalls at 1 and 6 postnatal months, and reported breastfeedings per day. The Bayley-III Scales of Infant Development were administered at 24 postnatal months to assess infant cognition. Linear regressions were used to examine associations, reported as unstandardized (B) coefficients, 95% CIs, and P values. Results Mothers consumed 1656 ± 470 kcal, 21.8 ± 12 g fructose, and 2.5 ± 2.6 servings SSBs + J, and reported 6.9 ± 2.1 breastfeedings per day at 1 postnatal month. Controlling for maternal age, prepregnancy BMI, education level, kilocalories, infant age, sex, and birthweight revealed that infant cognitive development scores at 24 postnatal months correlated inversely with maternal fructose consumption at 1 postnatal month (B = −0.08; 95% CI = −0.13, −0.03; P < 0.01). The association of infant cognitive development scores with maternal fructose consumption was no longer significant after adjustment for maternal SSB + J intake (B = −0.05; 95% CI = −0.10, 0.00; P = 0.07), whereas maternal SSB + J intake was significant in the same model (B = −0.29; 95% CI = −0.52, −0.05; P = 0.02). Infant cognitive development scores were not associated with maternal fructose and SSB + J consumption at 6 postnatal months. Conclusions Our findings suggest that infant neurodevelopmental outcomes at 24 postnatal months can be adversely influenced by maternal fructose intake in early lactation, and this could be attributed to maternal SSB + J intake.

Bilingualism affects infant cognition: Insights from new and open data

Bilingualism has been hypothesized to shape domain-general cognitive abilities across the lifespan, in what some have called the “bilingual advantage”. Here, we examined the replicability of a seminal study that showed monolingual–bilingual differences in infancy (Kovács & Mehler, 2009a) by collecting new data from 7-month-olds and 20-month-olds and reanalyzing three open datasets from 7–9 month-olds (D’Souza et al., 2020, Experiment 1; Kalashikova et al., 2020, Visual and Auditory conditions). All infants (total N = 181) were tested in an anticipatory eye movement paradigm, where they learned to use a visual and/or auditory cue to anticipate a visual reward presented consistently on one side of a screen during training, and on the opposite side of the screen at test. To correctly anticipate the reward at test, infants had to update their previously learned behavior. Across 3 out of 4 studies, results from a new analytic approach showed that 7–9 month-old bilinguals were better able to update the previously-learned response at test (a “bilingual advantage”), which could be related to bilinguals’ weaker initial learning of the contingency during the learning phase (a “monolingual advantage”). At 20 months, bilinguals performed better at test, though groups showed similar performance during the learning phase. Overall, these results show that bilingualism affects how infants process both new and updated information during learning.

Infant Precursors of Executive Function in Down Syndrome

Background. Though early features of infant cognition are predictive of executive function (EF) in typically developing (TD) children, there is little information regarding the developmental origins of EF in neurogenetic conditions, such as Down syndrome (DS). Methods. The current study compared the performance of infants with and without DS on four dimensions that are hypothesized EF precursors: attention shifting, sustained attention, processing speed, and action planning. The relationship between these EF precursors at Time 1 and EF performance at Time 2 (6 months later) was also examined in the DS group. Participants were 58 infants with DS, M chronological age = 11.32 months, SD = 3.50; M developmental age = 7.93 months, SD = 2.79, and 40 TD infants, M chronological age = 8.14, SD = 3.25; M developmental age = 8.18 months, SD = 3.51. Results. Results showed that infants with DS shifted their attention more slowly, looked at objects for longer durations, and demonstrated a longer latency to contact objects when compared to TD infants at Time 1. Attention shifting at Time 1 significantly predicted EF performance at Time 2 in the DS group. Conclusions. This study provides evidence that an early atypical presentation of EF precursors is detectable during infancy in DS and is predictive of subsequent EF performance. These findings contribute to the identification of areas of early cognitive risk in DS and can inform future interventions in this population.

Do 15-month-old infants prefer helpers? A replication of Hamlin et al . (2007)

Hamlin et al . found in 2007 that preverbal infants displayed a preference for helpers over hinderers. The robustness of this finding and the conditions under which infant sociomoral evaluation can be elicited has since been debated. Here, we conducted a replication of the original study, in which we tested 14- to 16-month-olds using a familiarization procedure with three-dimensional animated video stimuli. Unlike previous replication attempts, ours uniquely benefited from detailed procedural advice by Hamlin. In contrast with the original results, only 16 out of 32 infants (50%) in our study reached for the helper; thus, we were not able to replicate the findings. A possible reason for this failure is that infants' preference for prosocial agents may not be reliably elicited with the procedure and stimuli adopted. Alternatively, the effect size of infants’ preference may be smaller than originally estimated. The study addresses ongoing methodological debates on the replicability of influential findings in infant cognition.