Learning to Crawl

The effects of infants' age, body dimensions, and experience on the development of crawling was examined by observing 28 infants longitudinally, from children's first attempts at crawling until they began walking. Although most infants displayed multiple crawling postures en route to walking, development did not adhere to a strict progression of obligatory, discrete stages. In particular, 15 infants crawled on their bellies prior to crawling on hands and knees, but the other 13 infants skipped the belly-crawling period and proceeded directly to crawling on hands and knees. Duration of experience with earlier forms of crawling predicted the speed and efficiency of later, quite different forms of crawling. Most important, infants who had formerly belly crawled were more proficient crawling on hands and knees than infants who had skipped the belly-crawling period. Transfer could not be explained by differences in infants' age or body dimensions alone. Rather, experience using earlier crawling patterns may have exerted beneficial effects on hands-and-knees crawling by shoring up underlying constituents common to all forms of crawling postures.     

A Longitudinal Study of Intralimb Coordination in the First Year of Independent Walking: A Dynamical Systems Analysis

Using a dynamical systems approach, we examined the development of intralimb coordination over the first year of independent walking. The segmental motion of the thigh and shank and their intralimb coordinative relationship were modeled dynamically as a system of coupled limit cycles. To test the predictions of such a dynamic model in the development of intralimb coordination, 3 infants were filmed from the onset of their first upright independent walking steps, and weekly for the next month and then every month thereafter until they had been walking for 1 year. 3 adults also were included for comparison. Analysis of the kinematics data derived from the film revealed that at the emergence of walking, the limit cycle system displayed instability in several aspects. With walking experience, however, the limit cycle regime became more attractive, such that by 3 months of walking the infants appeared to have found an adult-like stable coordinative relationship between the 2 segments. This pattern of instability followed by stability is consisted with the transitional behaviors of dynamical systems. Several potential control parameters are discussed that might contribute to the stabilization of the walking behavior. The utility of employing a dynamical systems approach for understanding developing behavioral systems is discussed.     

Tactile training facilitates infants' ability to reach to targets on the body

This longitudinal study investigated the effect of experience with tactile stimulation on infants' ability to reach to targets on the body, an important adaptive skill. Infants were provided weekly tactile stimulation on eight body locations from 4 to 8 months of age (N = 11), comparing their ability to reach to the body to infants in a control group who did not receive stimulation (N = 10). Infants who received stimulation were more likely to successfully reach targets on the body than controls by 7 months of age. These findings indicate that tactile stimulation facilitates the development of reaching to the body by allowing infants to explore the sensorimotor correlations emerging from the stimulation.     

Transition from crawling to walking and infants' actions with objects and people

Associations between infants' transition to walking and object activities were examined. Fifty infants were observed longitudinally during home observations. At 11 months, all infants were crawlers; at 13 months, half became walkers. Over age, infants increased their total time with objects and frequency of sharing objects with mothers. Bidirectional influences between locomotion and object actions were found. Walking was associated with new forms of object behaviors: Walkers accessed distant objects, carried objects, and approached mothers to share objects; crawlers preferred objects close at hand and shared objects while remaining stationary. Earlier object activities predicted walking status: Crawlers who accessed distant objects, carried objects, and shared objects over distances at 11 months were more likely to walk by 13 months.     

A study of multimodal motherese: the role of temporal synchrony between verbal labels and gestures

This study examined European American and Hispanic American mothers' multimodal communication to their infants (N = 24). The infants were from three age groups representing three levels of lexical-mapping development: prelexical (5 to 8 months), early-lexical (9 to 17 months), and advanced-lexical (21 to 30 months). Mothers taught their infants four target (novel) words by using distinct objects during a semistructured play episode. Recent research suggests that young infants rely on temporal synchrony to learn syllable-object relations, but later, the role of synchrony diminishes. Thus, mothers' target and nontarget naming were coded for synchrony and other communication styles. The results indicated that mothers used target words more often than nontarget words in synchrony with object motion and sometimes touch. Thus, "multimodal motherese" likely highlights target word-referent relations for infants. Further, mothers tailored their communication to infants' level of lexical-mapping development. Mothers of prelexical infants used target words in synchrony with object motion more often than mothers of early- and advanced-lexical infants. Mothers' decreasing use of synchrony across age parallels infants' decreasing reliance on synchrony, suggesting a dynamical and reciprocal environment-organismic relation.     

Comparing the phonological and double deficit hypotheses for developmental dyslexia

This study tested the predictions of thephonological and double deficit hypotheses byexperimentally examining speech perception,phoneme awareness, lexical retrieval (serialand discrete), articulatory speed, and verbalSTM in school age child (N = 35) and adolescent(N = 36) dyslexics, and both chronological age(CA) and reading age (RA) controls. Theresults confirmed the findings of previousstudies of a deficit in phoneme awareness indevelopmental dyslexia. At both age levels,dyslexics performed significantly more poorlythan both their CA and RA controls. Althoughdeficits in the other processes investigated,particularly in rapid serial naming, were alsoapparent, they were not as clear-cut as thedeficit in phoneme awareness. In general,definite evidence of a deficit in rapid serialnaming was limited to the more severelyimpaired dyslexics. Furthermore, although rapidserial naming contributed independent variationto various literacy skills, its contributionwas modest relative to the contribution ofphoneme awareness, regardless of whether theliteracy skill relied more or less heavily onphonological or orthographic coding skills. Further analyses suggested that variation inrapid serial skill is particularly importantfor fluent reading of text, whereas phonemeawareness is particularly important for thedevelopment of the ability to read byphonologically recoding letters or groups ofletters in words into their phonological codes.This explains the relatively strongcontribution of phoneme awareness to readingand spelling ability in general. In sum, thephonological hypothesis offers a moreparsimonious account of the present resultsthan the double deficit hypothesis.     

Early reading development in children at family risk for dyslexia

In a 3-year longitudinal study, middle- to upper-middle-class preschool children at high family risk (HR group, N = 67) and low family risk (LR group, N = 57) for dyslexia (or reading disability, RD), were evaluated yearly from before kindergarten to the end of second grade. Both phonological processing and literacy skills were tested at each of four time points. Consistent with the well-known familiarity of RD, 34% of the HR group compared with 6% of the LR group became RD. Participants who became RD showed deficits in both implicit and explicit phonological processing skills at all four time points, clearly indicating a broader phonological deficit than is often found at older ages. The predictors of literacy skill did not vary by risk group. Both risk groups underwent a similar developmental shift from letter-name knowledge to phoneme awareness as the main predictor of later literacy skill. This shift, however, occurred 2 years later in the HR group. Familial risk was continuous rather than discrete because HR children who did not become RD performed worse than LR non-RD children on some phonological and literacy measures. Finally, later RD could be predicted with moderate accuracy at age 5 years, with the strongest predictor being letter-name knowledge.     

Effects of maternal absence due to employment on the quality of infant-mother attachment in a low-risk sample

Recent reports have suggested that day-care experience initiated prior to 12 months of age is associated with increased proportions of infants whose attachment to mother is classified as "insecure-avoidant." However, reviewers have questioned the generality of these findings, noting that samples in which associations between early day-care experience and avoidant attachment patterns have been reported come from high-risk populations, and/or that the infants' day-care settings may not have been of high quality. In the present study, effects of maternal absences on infant-mother attachment quality were assessed in a low-risk, middle-class sample (N = 110). In all instances, substitute care had been initiated at least 4 months prior to the infant's first birthday and was provided in the infant's home by a person unrelated to the baby. Infants were assessed using the Ainsworth Strange Situation when they were 12-13 months of age. Analyses indicated that a significantly greater proportion of infants whose mothers worked outside the home (N = 54) were assigned to the category "insecure-avoidant" as compared to infants whose mothers remained in the home (N = 56) throughout the first year of life. Analyses of demographic and psychological data available for the sample indicated that this relation is dependent upon maternal parity (primi- vs. multiparous mother). The association between attachment quality and work status was significant only for firstborn children of full-time working mothers. The results are interpreted as evidence that the repeated daily separations experienced by infants whose mothers are working full-time constitute a "risk" factor for the development of "insecure-avoidant" infant-mother attachments.     

Continuity and discontinuity of behavioral inhibition and exuberance: psychophysiological and behavioral influences across the first four years of life

Four-month-old infants were screened (N = 433) for temperamental patterns thought to predict behavioral inhibition, including motor reactivity and the expression of negative affect. Those selected (N = 153) were assessed at multiple age points across the first 4 years of life for behavioral signs of inhibition as well as psychophysiological markers of frontal electroencephalogram (EEG) asymmetry. Four-month temperament was modestly predictive of behavioral inhibition over the first 2 years of life and of behavioral reticence at age 4. Those infants who remained continuously inhibited displayed right frontal EEG asymmetry as early as 9 months of age while those who changed from inhibited to noninhibited did not. Change in behavioral inhibition was related to experience of nonparental care. A second group of infants, selected at 4 months of age for patterns of behavior thought to predict temperamental exuberance, displayed a high degree of continuity over time in these behaviors.     

Grown-ups are not afraid of scary stuff, but kids are: young children's and adults' reasoning about children's, infants', and adults' fears

Three-, 5-, and 7-year-olds and adults ( N = 64) listened to stories depicting 2 protagonists of different ages (infant and child or child and grownup) that encounter an entity that looks like a real (e.g., a snake) or an imaginary (e.g., a ghost) fear-inducing creature. Participants predicted and explained each protagonist's intensity of fear. Results showed significant age-related increases in knowledge that infants and adults would experience less intense fears than young children and that people's fears are causally linked to their cognitive mental states. Across age, stories involving imaginary beings elicited more frequent mental explanations for fear than stories about real creatures. Results are discussed in relation to children's developing awareness of the mind as mediating between situations and emotions.     

Baby carriage: infants walking with loads

Maintaining balance is a central problem for new walkers. To examine how infants cope with the additional balance control problems induced by load carriage, 14-month-olds were loaded with 15% of their body weight in shoulder-packs. Both symmetrical and asymmetrical loads disrupted alternating gait patterns and caused less mature footfall patterns. Walking was most severely compromised by back loads. Infants with less walking experience, lower levels of walking proficiency, and chubbier body proportions were more adversely affected. In addition, infants displayed a unique postural response to asymmetrical loads. In contrast to older children and adults, infants leaned with loads rather than in the opposite direction to the loads. Findings are discussed in terms of development from accommodation to compensatory strategies.     

Developmental changes in endogenous control of attention: the role of target familiarity on infants' distraction latency

This study evaluated the interactive effects of endogenous and exogenous influences on infants' attention allocation by assessing the role of target familiarity on distraction latency during object exploration. In Experiment 1 (N = 54), infants' distraction latencies as they investigated both familiar toys (ones they previously had seen in a familiarization procedure) and novel toys (ones they had not seen in the familiarization procedure) were assessed longitudinally at 6.5 and 9 months of age. In Experiment 2 (N = 32), infants' distraction latencies were assessed at either 6.5 or 10 months as they investigated either familiar or novel targets. In both experiments, older infants, but not younger infants, exhibited longer latencies as they investigated novel toys as compared with their latencies as they investigated familiar toys. These results are discussed in terms of developmental changes in the interactive effects of endogenous and exogenous factors controlling attention allocation.     

Crawling versus Walking Infants' Perception of Affordances for Locomotion over Sloping Surfaces

14-month-old toddlers vs. 8.5-month-old crawling infants were encouraged to ascend and descend a sloping walkway (10°, 20°, 30°, and 40°). Infants in both locomotor groups overestimated their ability to ascend slopes. However, on descending trials where falling was more aversive, most toddlers switched from walking to sliding positions for safe descent, but crawlers plunged down headfirst and many fell at each increment. Toddlers touched and hesitated most before descending 10° and 20° slopes, and they explored alternative means for descent by testing out different sliding positions before leaving the starting platform. In contrast, crawlers touched and hesitated most before descending 30° and 40° slopes, and they never explored alternative sliding positions. In addition, we analyzed measures of locomotor skill and experience in relation to children's ability to perceive affordances. Findings indicate that children must learn to perceive affordances for locomotion over slopes and that learning may begin by fine-tuning of exploratory activity.     

Development of subjective recollection: understanding of and introspection on memory States

The development of subjective recollection was investigated in participants aged 6-18 years. In Experiment 1 (N = 90), age-related improvements were found in understanding of the subjective experience of recollection, although robust levels of understanding were observed even in the youngest group. In Experiment 2 (N = 100), age-related differences were found in subjective recollection during a memory task, suggesting development not only in the ability to reflect on memory states, but also in the informational basis of subjective recollection. Lower understanding of memory states was associated with increased propensity to claim recollection. These results indicate that subjective recollection develops considerably during childhood and suggest that the development of metamemory supports this capacity.     

Find Your Manners: How Do Infants Detect the Invariant Manner of Motion in Dynamic Events?

To learn motion verbs, infants must be sensitive to the specific event features lexicalized in their language. One event feature important for the acquisition of English motion verbs is the manner of motion. This article examines when and how infants detect manners of motion across variations in the figure's path. Experiment 1 shows that 13- to 15-month-olds (N = 30) can detect an invariant manner of motion when the figure's path changes. Experiment 2 reveals that reducing the complexity of the events, by dampening the figure's path, helps 10- to 12-month-olds (N = 19) detect the invariant manner. These findings suggest that: (a) infants notice event features lexicalized in English motion verbs, and (b) attention to manner can be promoted by reducing event complexity.     

Infants' Responses to Frustrating Situations: Continuity and Change in Reactivity and Regulation

We examined continuity, stability, and change in behaviors reflecting infant reactivity and regulation. Healthy infants were observed in laboratory situations designed to elicit frustration when they were 5 ( N = 87) and 10 months of age ( N = 82) Behaviors indicative of reactivity included objective ratings of average intensity cry, peak intensity cry, and latency to cry. In addition, durations of orienting, avoidant, and nonnegative communicative behaviors were assessed as measures of regulation at each age. Results showed that several behaviors changed in level over time. In addition, Confirmatory Factor Analysis revealed both structural continuity and discontinuity: Behaviors were organized into 2 similar factors at 5 and 10 months (Reactivity and Regulation), but the relation between reactivity and regulation became increasingly independent over time, such that reactivity and regulation were negatively correlated at 5 months but not at 10 months. Finally, model-fitting revealed cross-dimension but not within-dimension stability (5-month reactivity predicted 10-month regulation).     

Cliff or Step? Posture‐Specific Learning at the Edge of a Drop‐Off

Infants require locomotor experience to behave adaptively at a drop‐off. However, different experimental paradigms (visual cliff and actual gaps and slopes) have generated conflicting findings regarding what infants learn and the specificity of their learning. An actual, adjustable drop‐off apparatus was used to investigate whether learning to distinguish a step from a cliff transfers from crawling to walking. Experienced 12‐month‐old crawlers (n = 16) refused to crawl over risky drop‐offs but novice 12‐month‐old walkers (n = 17) stepped repeatedly over the edge. Experienced 18‐month‐old walkers (n = 18) refused to walk over risky drop‐offs but descended using alternative methods. These findings suggest that infants do not acquire generalized responses like fear or wariness of heights. Rather, infants learn to perceive affordances for the experienced action.     

Evidence for referential understanding in the emotions domain at twelve and eighteen months

Infants as young as 12 months readily modulate their behavior toward novel, ambiguous objects based on emotional responses that others display. Such social-referencing skill offers powerful benefits to infants' knowledge acquisition, but the magnitude of these benefits depends on whether they appreciate the referential quality of others' emotional messages, and are skilled at using cues to reference (e.g., gaze direction, body posture) to guide their interpretation of such messages. Two studies demonstrated referential understanding in 12- and 18-month-olds' responses to another's emotional outburst. Infants relied on the presence versus absence of referential cues to determine whether an emotional message should be linked with a salient, novel object in the first study (N = 48), and they actively consulted referential cues to disambiguate the intended target of an affective display in the second study (N = 32). These findings provide the first experimental evidence of such sophisticated referential abilities in 12-month-olds, as well as the first evidence that infant social referencing at any age actually trades on referential understanding.     

检察官应对方式与自我效能感的调查研究

研究旨在探讨检察官的自我效能感状况和应对方式的选择,以促进检察官提高自我效能感和采取更积极的应对方式。采用简易应对方式问卷(Simplified Coping Style Questionnaire,SCSQ)和一般自我效能感量表(GSES),对中国4个省748位检察官进行调查和检测,并对他们的性别、年龄、工龄、教育水平、职务和工作部门等情况进行分析。结果显示检察官群体更倾向于选择积极的应对方式(t=7.288,p<0.01),而较少采用消极的应对方式(t=-44.579,p<0.01);但是在自我效能上却低于普通人常模(t=-20.187,p<0.01)。不同职务的检察官在积极应对方面差异有统计学意义(P<0.05)。不同性别,不同工龄,不同职务和不同部门的检察官在自我效能上的差异有统计学意义(P<0.05)。因此认为,提高检察官的准入门槛,适时地进行培训,能改善检察官的应对方式;适当减压,能提高检察官的自我效能感;艰难而费事的工作应当尽可能分配给年龄大、工龄长的检察官。     

Infant reactivity and reliance on mother during emotion challenges: prediction of cognition and language skills in a low-income sample

This investigation considers the association between patterns of emotional reactivity and reliance on mother in infancy and cognitive and language developments at age 2. Low-income women (N = 518) and their firstborn infants participated in (1) a lab-based assessment where emotion challenges were presented when the infants were 6 to 9 months old, and (2) an assessment of language and cognitive skills at age 2. After controlling for birthweight, early sensorimotor delay, and age at testing, infants who displayed a pattern of combined high reactivity and high reliance on mother in response to positive, anger, and fear emotion challenges had higher cognitive and language skills at age 2 compared with infants who displayed patterns of low reactivity and low reliance on mother. Children who showed high fearful distress and low reliance on mother and whose mothers had low psychological resources had especially poor developmental outcomes. The role of maternal availability in the socialization of emotion and early communication is discussed.