Visual short-term memory in the first year of life: capacity and recency effects.

A span task was developed to assess the amount of information infants could hold in short-term memory. In this task, infants were presented with up to 4 items in succession and then tested for recognition by successively pairing each item with a novel one. A large sample of full-terms and low-birth-weight preterms (< 1,750 g) was tested longitudinally, at 5, 7, and 12 months of age. Results were similar for both groups: (a) Longer spans were more difficult, especially at the 2 younger ages; (b) memory capacity increased over the 1st year of life--whereas less than 25% of the sample could hold as many as 3-4 items in mind at once at the younger ages, nearly half could do so by 12 months of age; (c) there was a marked recency effect (greater memory for the final item) for spans of 3 and 4 at all ages; and (d) there were modest cross-age correlations, indicating that individual differences in memory capacity showed some stability from age to age.     

Language specific prosodic preferences during the first half year of life: Evidence from German and French infants

There is converging evidence that infants are sensitive to prosodic cues from birth onwards and use this kind of information in their earliest steps into the acquisition of words and syntactic regularities of their target language. Regarding word segmentation, it has been found that English-learning infants segment trochaic words by 7.5 months of age, and iambic words only by 10.5 months of age [Jusczyk, P. W., Houston, D. M., & Newsome, M. (1999). The beginnings of word segmentation in English-learning infants. Cognitive Psychology, 39, 159–207]. The question remains how to interpret this finding in relation to results showing that English-learning infants develop a preference for trochaic over iambic words between 6 and 9 months of age [Jusczyk, P. W., Cutler, A., & Redanz, N. (1993). Preference for the predominant stress patterns of English words. Child Development, 64, 675–687]. In the following, we report the results of four experiments using the headturn preference procedure (HPP) to explore the trochaic bias issue in German- and French-learning infants. For German, a trochaic preference was found at 6 but not at 4 months, suggesting an emergence of this preference between both ages (Experiments 1 and 2). For French, 6-month-old infants did not show a preference for either stress pattern (Experiment 3) while they were found to discriminate between the two stress patterns (Experiment 4). Our findings are the first to demonstrate that the trochaic bias is acquired by 6 months of age, is language specific and can be predicted by the rhythmic properties of the language in acquisition. We discuss the implications of this very early acquisition for our understanding of the emergence of segmentation abilities.     

Influence of breastfeeding and iron status on mental and psychomotor development during the first year of life.

Breastfeeding (BF) confers numerous benefits on the developing infant in both the short and the long term including psychological development, but there are multiple other factors that must be taken into account when these relationships are studied. To analyse how breastfeeding during the first 4 months of life affects infant mental and psychomotor development (MPD) at 6 and 12 months in a group of healthy infants from a Mediterranean Spanish city considering many important potential confounds. This is a longitudinal study conducted on infants from birth until the age of 12 months. A total of 154 healthy infants were evaluated by Paediatric Unit of Sant Joan University Hospital in Reus, Spain. Type of feeding, clinical history, anthropometry, iron status and mental and psychomotor development were assessed and analysed. At 4 months, 24% of infants received BF and 26% received mixed feeding (MF). Multiple Linear Regression models were applied adjusting for potential prenatal, perinatal and postnatal confounds showing that infants who received BF for at least four months presented higher psychomotor development index (PDI) at 6 and at 12 months of age. Also, gestational age and BMI at 6 m were associated positively with PDI at 6 m, and haemoglobin levels at 12 m and birth height were associated with PDI and MDI at 12 m (respectively).In conclusion, after the adjustment of important potential confounds, BF during at least four months and adequate infant iron status are related to better psychomotor development during the first year. No associations were found between BF and mental development.     

Native-language sensitivities: evolution in the first year of life

In the first few months of their lives, human infants can perceive differences in phonetic contrasts not present in their environment and that their parents cannot discriminate. At 12 months, their pattern of discrimination approaches that of their parents. Until recently, it was believed that the perception of native-language categories did not significantly evolve in that period. Kuhl et al. offer compelling new evidence indicating significant increase in native-language perception.     

Infant temperament and maternal sensitivity behavior in the first year of life

Maternal sensitivity behavior (MSB) and infant temperament were investigated among 56 Finnish low-risk mothers and their full-term and healthy infants. The mothers were from families with good economic status, the infant's parents lived together, and the mothers were well educated. Mothers and infants were video-recorded in free-play situations at home, and evaluated using the Parent-Child Early Relational Assessment Scale (PCERA). The infants were also assessed using the Revised Infant Temperament Questionnaire (R-ITQ) and the Toddler Temperament Questionnaire (TTQ). Most of the temperament characteristics showed moderate stability during the first year. MSB was related to infant temperament characteristics at 3, 6 and 12 months of age. Gender differences in temperament were evident already at 6 and 12 months of age. Few prior studies have reported gender differences in infancy.     

Continuity in mind-mindedness from pregnancy to the first year of life

Relations between parents' representations of the unborn child and postpartum infant-parent interaction were investigated in 25 couples and 3 solo mothers. In the last trimester of pregnancy, participants reported on involvement with the fetus and predicted what the unborn child would be like at age 6 months. Mothers (n=21) and fathers (n=17) were observed during separate interactions with their 6-month olds, which yielded measures of their tendency appropriately to interpret their infants' internal states (mind-mindedness). Parents' involvement with the fetus was unrelated to antenatal predictions and to postnatal mind-mindedness. Parents who had predicted more about the unborn child's characteristics were more likely to comment appropriately on their infants' internal states during infant-parent interaction. For fathers, overall antenatal predictions were also positively associated with misinterpretations of their infants' thoughts and feelings. Findings are discussed with reference to mind-mindedness being governed by caregiver-centered factors and differences between mothers and fathers in caregiving practices.     

Generalization of deferred imitation during the first year of life

Infants first generalize across contexts and cues at 3 months of age in operant tasks but not until 12 months of age in imitation tasks. Three experiments using an imitation task examined whether infants younger than 12 months of age might generalize imitation if conditions were more like those in operant studies. Infants sat on a distinctive mat in a room in their home (the context) while an adult modeled actions on a hand puppet (the cue). When they were tested 24 h later, 6-month-olds generalized imitation when either the mat or the room (but not both) differed, whereas 9-month-olds generalized when both the mat and the room differed. In addition, 9-month-olds who imitated immediately also generalized to a novel test cue, whereas 6-month-olds did not. These results parallel results from operant studies and reveal that the similarity between the conditions of encoding and retrieval-not the type of task-determines whether infants generalize. The findings offer further evidence that memory development during infancy is a continuous function.     

A meta-analysis of mental rotation in the first years of life

Mental rotation, the cognitive process of moving an object in mind to predict how it looks in a new orientation, is coupled to intelligence, learning, and educational achievement. On average, adolescent and adult males solve mental rotation tasks slightly better (i.e., faster and/or more accurate) than females. When such behavioral differences emerge during development, however, remains poorly understood. Here we analyzed effect sizes derived from 62 experiments conducted in 1705 infants aged 3–16 months. We found that male infants recognized rotated objects slightly more reliably than female infants. This difference survives correction for small degrees of publication bias. These findings indicate that gender differences in mental rotation are small and not robustly detectable in the first months of postnatal life.

Research Highlights

• We analyzed effect sizes of 62 mental rotation experiments including 1705 infants.
• Looking time reveals that 3–16-months-old infants are able to perform mental rotation.
• Mental rotation is slightly more reliable in male infants compared to female infants.
• Gender difference in mental rotation is robust to small degrees of publication bias.

     

Consistency in maternal affect and positive vocalization over the first year of life

Consistency in parenting infants has positive developmental outcomes. Yet, the role of socioeconomic status (SES) in consistency of maternal behaviors is not well understood. We investigated individual-order continuity of maternal smile and laughter and positive vocalization from 6 to 12 months of age in 82 mother-infant dyads. Overall, individual differences in maternal smile and laughter, and positive vocalization were consistent across time. A multidimensional measure of SES moderated the association of maternal smile and laughter from 6 to 12 months, such that infants from lower SES families were vulnerable to unpredictable parenting - experiencing a lack of consistency in maternal smiles and laughter.     

The developmental course of lexical tone perception in the first year of life

Perceptual reorganisation of infants' speech perception has been found from 6 months for consonants and earlier for vowels. Recently, similar reorganisation has been found for lexical tone between 6 and 9 months of age. Given that there is a close relationship between vowels and tones, this study investigates whether the perceptual reorganisation for tone begins earlier than 6 months. Non-tone language English and French infants were tested with the Thai low vs. rising lexical tone contrast, using the stimulus alternating preference procedure. Four- and 6-month-old infants discriminated the lexical tones, and there was no decline in discrimination performance across these ages. However, 9-month-olds failed to discriminate the lexical tones. This particular pattern of decline in nonnative tone discrimination over age indicates that perceptual reorganisation for tone does not parallel the developmentally prior decline observed in vowel perception. The findings converge with previous developmental cross-language findings on tone perception in English-language infants [Mattock, K., & Burnham, D. (2006). Chinese and English infants' tone perception: Evidence for perceptual reorganization. Infancy, 10(3)], and extend them by showing similar perceptual reorganisation for non-tone language infants learning rhythmically different non-tone languages (English and French).     

A longitudinal investigation of visual event-related potentials in the first year of life

The goal of the current study was to assess general maturational changes in the ERP in the same sample of infants from 4 to 12 months of age. All participants were tested in two experimental manipulations at each age: a test of facial recognition and one of object recognition. Two sets of analyses were undertaken. First, growth curve modeling with mixed models was used to examine trajectories of development and possible differences in trajectories based on recognition memory (novel versus familiar) and/or stimulus-specific memory (face versus object recognition). Our results suggest that the Pb, Nc and Slow Wave components change significantly in terms of amplitude and latency over the first year of life. Pb amplitude showed a significant non-linear increase over time, whereas Pb latency showed a significant linear decrease over time with a plateau beginning at 10 months. Nc amplitude showed a significant linear decrease over time (i.e. a stronger negative value), whereas Nc latency showed a significant linear decrease over time, with a plateau beginning at 8 months. Second, to relate our findings to those reported in the literature, we examined the effects of memory and stimulus and their combination. Differences between recognition memory and stimulus specific memory were found in the responses to familiar and novel faces and objects for all three components, although the pattern differed across the five ages. These results have implications for future studies that involve the recording of the visual ERP, and point to the advantages of growth curve modeling in examining longitudinal data to account for non-linear development.     

The longitudinal associations between temperament and sleep during the first year of life

Temperament and sleep in infants are related but also distinct concepts. The longitudinal effects of temperament on sleep in infancy remain unclear, although this information is potentially important for the prevention and treatment of early sleep problems. We examined how various temperament features influence sleep development during the first year of life in a large birth cohort. This study comprised mother-infant dyads with complete longitudinal data on sleep, temperament and sociodemographic measurements at six and 12 months (N = 1436). We observed that higher infant Negative Affectivity was related to several sleep problems, and that many subscales of Negative Affectivity and Orienting/Regulation predicted worse sleep and deterioration in sleep problems from six to 12 months. Few associations between Surgency and sleep were found. Our findings highlight especially Negative Affectivity as a risk factor for persistent and increasing sleep problems, and also the specific importance of the fine-grained aspects of temperament in predicting infant sleep development.     

Dimensions of naturally occurring mother-infant separations during the first year of life

The goals of this paper are (1) to introduce a methodology developed to study mother-infant separations that occur in the context of normal family life, including but going beyond separations associated with maternal employment; (2) to present illustrative data that describe the range of separations experienced by one sample of infants; and (3) to demonstrate how a focus on specific underlying dimensions results in a more precise characterization of the separation experience. It is necessary to identify the specific dimensions on which mother-infant separations vary in order to clarify which aspects of separation are relevant to child outcome. Detailed histories of mother-infant separations and concomitant substitute care during the first year of life were obtained by interview from 144 middle-class mothers of first-born infants. Far from being an unusual event, separation from mother was a normal experience during infancy for this sample. Six types of separation were identified, the majority of which have not been studied previously. Analyses indicated that naturally occurring mother-infant separations can be differentiated statistically and compared in terms of amount of separation, stability of care, characteristics of caregivers, and characteristics of the substitute care setting.     

Meaning structures and mental representations

This paper argues for a distinction between meaning structure and mental representation, and presents the outlines of a theoretical model of their interrelationship. Meaning structures are defined as structures in the human mind/brain which develop as the combined result of genetic predispositions and individual experience, and lead to relatively stable patterns of perceiving, thinking, feeling, behaving, etc. Mental representation is defined as the aspect of mental processes which involves imagining and thinking of things that are not perceptually present. It is suggested that the mind includes a central network of meaning structures (CNMS) for the storage of information, and a number of other subsystems (e.g., perceptual systems, behavioral systems, and a verbal system) for the processing of externally and internally generated information. Against the dual-coding theory, it is argued that there is one code for the long-term storage of information, but several codes for the processing of information. Mental representations are seen as products of activation that is spread from the CNMS to more peripheral systems. The spread of activation from the CNMS to perceptual systems results in mental imagery; when activation spreads to the verbal system the result is conceptual thinking; and when activation spreads to behavioral systems it produces intentions. It is argued that this conceptual model can help to solve some basic theoretical problems that have plagued cognitive psychology.     

Maternal anxiety and depression and development of prematurely born infants in the first year of life

The purpose of this study was: (a) to assess and to compare anxiety and depression symptoms in mothers of preterm neonates during hospitalization in the Neonatal Intensive Care Unit, after discharge, and at the end of the infants' first year of life; and (b) to assess the child's development at 12 months of chronological corrected age (CCA). Thirty-six mothers, with no psychiatric antecedents assessed with the SCID-NP, were evaluated by STAI and BDI. The infants were assessed with Bayley-II Scales. There was a significant decrease in clinical symptoms of state-anxiety in mothers (p = .008), comparing the period during hospitalization and after discharge of the infants. Clinical symptoms of anxiety and depression were observed in 20% of the mothers at the end of the infants' first year of age. The majority of the infants exhibited normal development on Bayley-II at 12 months CCA; however, 25% of the infants displayed cognitive problems and 40% motor problems. The mothers' anxiety and depression symptoms decreased at the end of the first year of life of the pre-term infants and the children showed predominately normal development at this phase.