Memory for events and locations obtained in the context of elicited imitation: evidence for differential retention in the second year of life

Previous research has suggested that infants may have more robust memory for past experiences relative to memory for locations that have been encountered previously. This assertion, however, primarily results from the comparison of data that were collected using different experimental procedures. In the present study, we examined memory for events and memory for locations in the context of elicited imitation. Specifically, 13-, 16-, and 20-month-old infants were tested for long-term memory for events and locations after between-subjects delays of 1, 3, 6, 9, and 12 months. The results indicated that the event memory was retained over lengthier delays relative to the location memory, despite superior encoding of location information. The possible adaptive significance of long-term memory for events ontogenetically preceding long-term memory for locations is discussed.     

The emergence of tool use during the second year of life

Despite a growing interest in the question of tool-use development in infants, no study so far has systematically investigated how learning to use a tool to retrieve an out-of-reach object progresses with age. This was the first aim of this study, in which 60 infants, aged 14, 16, 18, 20, and 22months, were presented with an attractive toy and a rake-like tool. There were five conditions of spatial relationships between the toy and the tool, going from the toy and tool being connected to there being a large spatial gap between them. A second aim of the study was to evaluate at what age infants who spontaneously fail the task can learn this complex skill by being given a demonstration from an adult. Results show that even some of the youngest infants could spontaneously retrieve the toy when it was presented inside and touching the top part of the tool. In contrast, in conditions with a spatial gap, the first spontaneous successes were observed at 18months, suggesting that a true understanding of the use of the tool has not been fully acquired before that age. Interestingly, it is also at 18months that infants began to benefit from the demonstration in the conditions with a spatial gap. The developmental steps for tool use observed here are discussed in terms of changes in infants' ability to attend to more than one item in the environment. The work provides insight into the progressive understanding of tool use during infancy and into how observational learning improves with age.     

Fixed ratio and extinction performance of infants in the second year of life

Five 14(1/2)- to 19(1/2)-month-old infants were trained to lever press for snacks on small fixed ratio schedules of reinforcement. Within four to nine sessions, responding under FR 10 was established for four subjects and FR 15 for the other. Each subject's last session revealed behavioral patterns similar to animal and human FR trained subjects-a high and constant ratio rate, mixed with a zero rate following reinforcements. Deviations were mostly in the form of prolonged and variable post-reinforcement pauses. These and other irregularities were probably due to the limited deprivation conditions and improper training procedures in which the ratio (for two subjects) was ascended too early and too quickly. Extinction was instituted during the last session. The degree to which extinction performance matched that of other organisms depended upon how stable and "ratio-like" performance was during conditioning.     

Children's understanding of communicative intentions in the middle of the second year of life

Two tasks were administered to 40 children aged from 16 to 20 months (mean age = 18;1), to evaluate children's understanding of declarative and informative intention [Behne, T., Carpenter, M., & Tomasello, M. (2005). One-year-olds comprehend the communicative intentions behind gestures in a hiding game. Developmental Science, 8, 492–499; Camaioni, L., Perucchini, P., Bellagamba, F., & Colonnesi, C. (2004). The role of declarative pointing in developing a theory of mind. Infancy, 5, 291–308]. In the first task, children had to respond to the experimenter who pointed at a distal object; in the second task, children had to find a toy in a hiding game after the experimenter indicated the correct location either by pointing or by gazing. In the first task, most children responded to the declarative gesture by “commenting” on the pointed object instead of just looking; however, looking responses were more frequent than commenting responses. In the second task, children chose the correct location of the object significantly more frequently when the informative gesture was the point than when it was the gaze; moreover, there were significantly more correct choices than incorrect choices in the point but not in the gaze condition. Finally, no significant relation was found between tasks. Taken together, the findings support the view that infants’ developing understanding of communicative intention is a complex process in which general cognitive abilities and contextual factors are equally important.     

An exploratory study of mother-child interaction during the second year of life

The aim of this study was to further understanding of development during the crucial second year of life. The study employed a naturalistic, semistructured situation for the observation of mother-child behavior. The experimental stimulus was the progressive diversion of the mother's attention away from her child. This diversion evoked separation anxiety in the child and the individual and interactive regulatory behaviors of the mother-child pair. Concurrently, the child's behavior was observed in a play group situation. One set of rating scales was devised for assessment of the mother-child interaction, and another set for assessment of the child's functioning in the play group. The major hypothesis was that maternal and child behaviors that foster the child's successful handling of phase-specific stresses and developmental tasks will be positively correlated with the child's functioning in the play group. This hypothesis is supported by the findings of the study.     

Memory reactivation effects independent of reconsolidation

Memory reactivation is an important process resulting from reexposure to salient training-related information whereby a memory is brought from an inactive to an active state. Reactivation is the first stage of memory retrieval but can result from the exposure to salient cues without any behavioral output. Such cue-induced reactivation, although frequently used by neuroscientists to study reconsolidation, has seldom been considered as a process in its own right and studied as such. This review presents arguments indicating that memory reactivation has two main consequences: (1) to enhance the accessibility of the target memory and (2) to make the memory malleable. Accordingly, reactivation creates a transient state during which the content of the memory is easily accessible and can be modified and/or updated. As both of these aspects can be observed shortly after memory reactivation, this review emphasizes that reconsolidation is not necessarily required for these processes and calls attention to reactivation as a factor in the dynamics of the memory.     

Shared focus in mother—child joint activity in the second year of life

Shared focus between mother and child during joint activity was examined. Ten dyads were observed at 16 and 20 months. We found that the level of conventionality expressed by shared focus increases with age. The activity becomes more oriented towards the cultural aspects of the objects than to material aspects, and social games become more oriented towards symbolic and linguistic aspects than to practical ones. Moreover, we found that the content of the game influences the function of the child's utterances both at 16 and at 20 months. These results point to the cultural specification of joint activity, which can be viewed as mediating the development of intersubjectivity as well as individual behaviour.     

From infant to child: the dynamics of cognitive change in the second year of life

The authors review several key areas of early cognitive development in which an abrupt shift in ability at the end of the second year of life has been traditionally assumed. These areas include deferred imitation, self-recognition, language, and categorization. Contrary to much conventional theorizing, the evidence shows robust continuities in all domains of early cognitive development. Where there is evidence of a reorganization of behavior that makes a new level of performance possible, dynamic-systems analyses indicate that even these may be driven by underlying processes that are continuous. Although there remain significant definitional and methodological issues to be resolved, the outcome of this review augers well for newer models in which cognitive development is viewed as a continuous, dynamic process.     

Memory reactivation and consolidation during sleep

Do our memories remain static during sleep, or do they change? We argue here that memory change is not only a natural result of sleep cognition, but further, that such change constitutes a fundamental characteristic of declarative memories. In general, declarative memories change due to retrieval events at various times after initial learning and due to the formation and elaboration of associations with other memories, including memories formed after the initial learning episode. We propose that declarative memories change both during waking and during sleep, and that such change contributes to enhancing binding of the distinct representational components of some memories, and thus to a gradual process of cross-cortical consolidation. As a result of this special form of consolidation, declarative memories can become more cohesive and also more thoroughly integrated with other stored information. Further benefits of this memory reprocessing can include developing complex networks of interrelated memories, aligning memories with long-term strategies and goals, and generating insights based on novel combinations of memory fragments. A variety of research findings are consistent with the hypothesis that cross-cortical consolidation can progress during sleep, although further support is needed, and we suggest some potentially fruitful research directions. Determining how processing during sleep can facilitate memory storage will be an exciting focus of research in the coming years.The idea that memory storage is supported by events that take place in the brain while a person is sleeping is an idea that is only rarely acknowledged in the neuroscience community. At present, most memory research proceeds with no mention of any influence of sleep on memory. Nonetheless, this hypothesis is gaining empirical support. Research into connections between memory and sleep represents a burgeoning enterprise at the crossroads of traditional memory research and sleep research, an enterprise poised to provide novel insights into the human experience.This article presents some speculations about connections between memory and sleep. We entertain the notion that declarative memories are subject to modification during sleep, and that enduring storage of such memories is systematically influenced by neural events taking place during sleep. Although other types of memory may also be subject to change during sleep (see Maquet et al. 2003), we emphasize declarative memory here.This article also functions as an introduction to the set of papers selected for this special issue of Learning & Memory. These papers together outline portions of the current empirical basis for memory-sleep connections, including research in humans and in nonhuman animals. The findings are tantalizing, and yet there are undoubtedly major gaps in our knowledge about the functions of sleep and about how sleep may be related to memory storage. Future research on this topic is bound to grow in exciting and unpredictable ways. Here, we explore questions about declarative memory and sleep that may serve as a useful guide for such research.     

Developmental changes in facial expressions of emotions in the strange situation during the second year of life

Infants' expressions of discrete emotions were coded during the more stressful episodes (4 through 8) of the Strange Situation at 13 and 18 months. The data showed a significant decrease in full-face expressions (more complex configurations of movements) and a significant increase in component expressions (simpler and more constrained patterns of movements). The authors interpreted this trend as a developmental change toward more regulated and less intense emotions. Consistent with this view, the aggregate index of infants' full-face negative emotion expressions, interpreted as reflecting relatively unregulated intense emotions, correlated significantly with maternal ratings of difficult temperament. The authors discuss alternative interpretations of the findings in terms of changes in reactivity/arousability and the emerging capacity for self-regulation.     

Infants in group care: their interactions with professional caregivers and parents across the second year of life

Seventy children were observed during structured play with their primary professional caregivers and three peers in the child care center and with their primary caregiving parents at home at 15 and 23 months of age. The same structured play tasks were used in the two settings and the quality of the children's interactions with caregivers and parents was rated using the same 7-point scales. As expected, the quality of caregiver–child interactions significantly increased between 15 and 23 months. At 15 months, the quality of caregiver–child interactions was significantly lower than the quality of parent–child interactions, particularly with regard to caregiver supportive presence and respect for the child's autonomy. At 23 months, however, the quality of caregiver–child interactions was no longer lower and in some respects even higher than the quality of parent–child interactions. At both ages, the children expressed more negativity towards their parents than towards their professional caregivers.     

Genetic and environmental relationships between head circumference growth in the first year of life and sociocognitive development in the second year: a longitudinal twin study

Although growth in head circumference (HC) during infancy is known to predict later childhood outcomes, the mechanisms underlying this association with later sociocognitive abilities remain undetermined. Thus, using a sample of 241 pairs of normally developing Japanese twins, this study investigated the underpinnings of the association between HC growth (difference between HC at birth and at 10 months) and sociocognitive abilities at 19 months as measured by 10 items from the M-CHAT. Phenotypic correlations between HC at birth and sociocognitive abilities and between HC growth and sociocognitive abilities were marginal and not significant. However, multivariate genetic analyses using Cholesky decomposition revealed that genetic influences on HC growth and those on sociocognitive abilities were negatively associated. On the other hand, shared and nonshared environmental influences on HC growth were positively associated with influences on sociocognitive abilities. Genetic and environmental influences on HC at birth were not significantly associated with influences on sociocognitive abilities. These results help to clarify the role of brain growth during infancy in the subsequent development of sociocognitive abilities and highlight the importance of examining the different roles of genetic and environmental influences in studies of these areas.     

Psychomotor performance of chilean infants from low socio-economic level during their second year of life

The psychomotor development of 1,406 low socioeconomic infants from Santiago, Chile, was examined. Four groups of infants were assessed: 12, 15, 18 and 21 months of age. Results indicated that as chronological age increased, the number of infants who fell into at-risk or delay categories increased.     

The relationship between motor development,gestures and language production in the second year of life: A mediational analysis

This longitudinal study investigated the relationships between motor, gestural and linguistic abilities using two parent report instruments. Motor skills at 12 months significantly correlated with language production at 16, 20 and 23 months, but these associations were mediated by the use of representational gestures.     

Attachment patterns and emotion regulation strategies in the second year

With the aim of studying the relationship between methods of emotion regulation and quality of attachment we examined 39 infants with different patterns of attachment, of whom 20 were classified as secure (B), 12 as avoidant (A) and 7 as resistant (C), assessing the regulatory strategies adopted by them during the Strange Situation at 13 months. Secure infants used strategies of positive social engagement more than insecure avoidant infants, while resistant infants displayed greater negative social engagement and less object orientation than the other two groups. Avoidant infants adopted positive and negative hetero-regulatory strategies less than the other groups, also differing from resistant infants in their greater use of object regulatory strategies. There were no significant differences as regards self-comforting regulation. Thus, the findings showed how the most significant differences to emerge between the groups concerned hetero-regulatory strategies, developed by the infant in interaction with attachment figures, and regulatory strategies oriented towards objects. Further analysis showed how the use by part of each attachment group of the emotion regulation strategies varies, differentiating the episodes of the SSP according to their level of stress.     

Socio-cognitive influences on the domain-specificity of prosocial behavior in the second year

The main aim of this study was to explain the domain-specificity of early prosocial behavior in different domains (i.e., helping, comforting, and cooperation) by simultaneously assessing specific socio-cognitive factors (i.e., self-other-differentiation and joint attentional skills) that were hypothesized to be differentially related to the three domains of prosocial behavior. Based on a longitudinal study design, observational and parental report data were collected when toddlers (N = 42) from German urban middle-class families were 15 and 18 months of age. At 15 months, regression analyses indicated differential relationships between socio-cognitive development and prosocial behavior (i.e., joint attentional skills were positively related with helping and, as hypothesized, both joint attentional skills and self-other differentiation were positively related with cooperation). Furthermore, self-other differentiation at 15 months predicted increases in coordination between 15 and 18 months. Finally, between 15 and 18 months, parental reports of socio-cognitive measures increased significantly while behavioral measures of both socio-cognitive concepts and prosocial behavior were stable across time. In sum, these results support the theoretical assumption of domain-specific socio-cognitive influences that constitute differential development of prosocial behavior. Implications of the results for theory and future studies are discussed from different perspectives with a focus on an interference interpretation calling for the integration of socialization approaches to the study of prosocial 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.