Is Visually Guided Reaching in Early Infancy a Myth?

The issue examined was whether infants require sight of their hand when first beginning to reach for, contact, and grasp objects. 7 infants were repeatedly tested between 6 and 25 weeks of age. Each session consisted of 8 trials of objects presented in the light and 8 trials of glowing or sounding objects in complete darkness. Infants first contacted the object in both conditions at comparable ages (mean age for light, 12.3 weeks, and for dark, 11.9 weeks). Infants first grasped the object in the light at 16.0 weeks and in the dark at 14.7 weeks, a nonsignificant difference. Once contact was observed, infants continued to touch and grasp the objects in both light and dark throughout all sessions. Because infants could not see their hand or arm in the dark, their early success in contacting the glowing and sounding objects indicates that proprioceptive cues, not sight of the limb, guided their early reaching. Reaching in the light developed in parallel with reaching in the dark, suggesting that visual guidance of the hand is not necessary to achieve object contact either at the onset of successful reaching or in the succeeding weeks.     

Sleep and Cognition in Preschool Years: Specific Links to Executive Functioning

This study investigated the prospective links between sleep in infancy and preschoolers' cognitive performance. Mothers of 65 infants completed a sleep diary when infants were aged 1 year, and children completed two subscales of the Wechsler Preschool and Primary Scale of Intelligence at 4 years, indexing general cognitive ability and complex executive functioning. Consistent with hypotheses, children getting higher proportions of their sleep at night as infants were found to perform better on executive functions, but did not show better general cognition. Relations held after controlling for family socioeconomic status and prior cognitive functioning. These findings suggest that the special importance of sleep for higher order cognition, documented among adults, may appear very early in life.     

From Walking to Running: Applying a Dynamical Systems Approach to the Development of Locomotor Skills

Developmental transitions of complex systems may be studied by selecting (collective) variables that constrain the degrees of freedom for each developmental state. In a dynamical systems approach, the transitions from state to state are engendered through the scaling of contributing subsystems (control parameters). In this study, the locomotor skills of walking and running were compared in newly running infants by observing several likely collective variables including relative stance, estimated pathway of center of mass, and segmental/joint action. 4 children were filmed longitudinally at 5.5, 7.5, and 9.5 months of independent walking and then at 3 years of age. 3 trials per gait were selected for single stride analysis and compared with data from 4 adults. In general, the proposed collective variables showed transitional forms over the first few months of running, indicating a relatively continuous change between the 2 gait forms. Coordination of the knee joint was very similar between gaits and across age, but the ankle joint was less consistent for both gaits in the infants. Relative stance and stride length data indicated that the children could not generate vertical and horizontal displacement. These findings echo those found in newly walking infants and suggest that similar rate-limiting parameters are present for both gaits.     

Can 5-month-old infants consider the perspective of a novel eyeless agent? New evidence for early mentalistic reasoning

Is early reasoning about an agent's knowledge best characterized by a mentalistic stance, a teleological stance, or both? In this research, 5-month-old infants (N = 64, 50% female, 83% White) saw a novel eyeless agent consistently approach object-A as opposed to object-B. Although infants could always see both objects, a screen separated object-B from the agent. When object-B protruded above the screen, infants interpreted the agent's actions as revealing a preference for object-A over object-B. When object-B did not protrude above the screen, however, infants refrained from attributing such a preference: Consistent with mentalistic accounts, they reasoned that the agent's representation of the scene did not include object-B, and they used the agent's incomplete representation, non-egocentrically, to interpret its actions.     

Modeling referential actions in 6- to 18-month-old infants: a precursor to symbolic understanding

Social precursors to symbolic understanding of pictures were examined with 100 infants ages 6, 9, 12, 15, and 18 months. Adults demonstrated 1 of 2 stances toward pictures and objects (contemplative or manipulative), and then gave items to infants for exploration. For pictures, older infants (12, 15, and 18 months) emulated the adult's actions following both types of demonstration trials. For objects, infants did not emulate actions following either stance at any age. The findings suggest that infants enlist their imitative learning skills in the context of learning the conventions of action on pictorial symbols. The data are interpreted as pointing to the importance of social learning in developing an understanding of the referential function of pictorial symbols.     

Infant Auditory Temporal Acuity: Gap Detection

The development of auditory temporal acuity during infancy was examined in 3-, 6-, and 12-month-old infants and in adults using the gap detection paradigm. Listeners detected a series of gaps, or silent intervals, or variable duration in a broadband noise. In order to vary the acoustic frequencies available to the listener, a high-pass noise was used to mask frequencies above specified cutoffs. High-pass maskers with cutoffs of 500, 2,000, and 8,000 Hz were used. The minimum detectable gap was determined using the Observer-based Psychoacoustic Procedure. The thresholds of 3- and 6-month-olds were considerably poorer than those of the adults, although the effect of masker condition was about the same for these 3 groups. The thresholds of 12-month-olds were significantly worse than the adults when the stimulus was unmasked or when the masker cutoff frequency was 2,000 or 8,000 Hz. When the masker cutoff frequency was 500 Hz, 12-month-olds fell into 2 groups: some had gap thresholds that were about the same as 3- and 6-month-olds, while some had gap thresholds that approached those of adults. In a second experiment, a larger group of 12-month-olds were tested with a 500-Hz masker cutoff. Average performance of 12-month-olds was about the same as that of 3- and 6-month-olds in Experiment 1. Some infants attained thresholds close to those of adults. Thus, gap detection thresholds are quite poor in infants, although the similarity of the effect of frequency on performance in infants and adults suggests that the mechanisms governing temporal resolution in infants operate qualitatively like those in adults.     

Visual Guidance in Infants' Reaching toward Suddenly Displaced Targets

This experiment evaluated the role of visual input about the location of a target object and the location of the hand in reaching by infants and adults. 5- and 9-month-old infants were presented with illuminated toys to reach for in a dark room. On no-switch trials, the toy remained illuminated throughout the infant's reach, whereas on switch trials the first-lit toy was replaced during the reach by a second-lit toy at a different position. On approximately half of the trials of each type a luminescent marker was attached to the reaching hand. Adult subjects (tested without the hand marker) fully compensated to the second-lit toy on switch trials, during a second reaching segment. On switch trials, 9-month-olds partially adjusted to the second-lit toy when wearing the hand marker and did not adjust without it. On no-switch trials, 9-month-olds reached just as accurately with or without the hand marker. 5-month-olds were generally inaccurate in their reaching and were unaffected by the presence or absence of the hand marker. The findings suggest that during the development of reaching there is an increase in visual guidance during the approach phase of reaches.     

Anticipatory Reaching by Infants and Adults: The Effect of Object Features and Apertures in Opaque and Transparent Screens

Perception of the manner in which objects may be grasped was examined in a series of experiments with adults and 10-month-old infants; visuomotor adjustment in hand orientation before making contact with objects served as the index throughout. In the first experiment, infants modified their hand orientation to match more closely the long axis of an object. They did so even though the target object could have been grasped by either end with hands oriented orthogonally to the long axis of the object. In two subsequent experiments involving reaching through narrow apertures to grasp the target, anticipatory adjustments in hand posture were evident for adults but not for infants. However, anticipatory adjustments by infants, sometimes appropriate and sometimes inappropriate, were made when the object was of such a size that it could neither be grasped nor retrieved through the aperture. In the final experiment, infants directed their hands first toward a handle, the only graspable part of an object, and oriented their hands so as to be nearly parallel with it prior to contact. This was the only orientation in which a grasp was possible. It was concluded that infants at 10 months respond more appropriately to object properties than to surface apertures that place limitations on how an object may be grasped.     

Smile production in older infants: the importance of a social recipient for the facial signal

2 studies tested the hypothesis that infant smile production depends on the availability of a social recipient for the facial signal, as well as on appropriate internal events. We examined the effects of attentive and inattentive, familiar and unfamiliar social objects on smile production in 1 1/2-year-old infants outside of social interactions. Like adults, these infants directed a majority of the smiles produced during nonsocial activity to an attentive social object. Overall smiling frequency was much lower when the only potential recipient (the mother) was inattentive, but the effect did not appear to be mediated by negative emotion. Only smiles directed to mother were reduced: nonsocial smiling (at the toys) was not sensitive to mother's inattention, and when an attentive, friendly stranger was present, she was accepted as a substitute target for social smiles. We conclude that an open channel of social communication promotes the outward expression of internal affect in infants.     

Perceiving "outside the box" occurs early in development: evidence for boundary extension in three- to seven-month-old infants

This investigation examined whether infants display boundary extension-a tendency to remember more of a visual scene than was presented. Three- to 7-month-olds were familiarized with a photograph of a visual scene, and tested with wide-angle versus close-up views of the scene. Infants preferred the close-up, indicating that they perceived the wide angle (the one consistent with boundary extension) as more familiar. Converging experiments showed that: (a) infants did not spontaneously prefer the close-up, (b) adults did not judge the wide angle to be more similar to the familiarization stimulus, and (c) infants spontaneously preferred the close-up when the photographs depicted outline objects without backgrounds. The findings suggest that infants anticipate information that lies beyond the borders of a scene view.     

Attachment in deaf mothers and their children

In attachment research, there has been a growing interest in how adults conceptualize their relationships with their own parents as well as in the transmission of attachment status from parent to child and the variables that influence that transmission. The primary goal of the present study was to examine the transmission of attachment from deaf mother to child. Adult Attachment Interviews were collected on 32 deaf women and Strange Situation Procedure data were obtained from their children. While the distribution of deaf mother attachment classifications was similar to that found with hearing samples, the concordance between mother and child in terms of attachment status was lower than in hearing samples. Having a deaf parent did not affect a deaf adult's attachment status. Post hoc analyses suggested a trend towards a dismissing stance in attachment relationships. Results are discussed in terms of variables affecting attachment status as well as the transmission of attachment.     

Teacher–child and child–child interactions in inclusive preschool settings: do adults inhibit peer interactions?

We conducted real-time analyses of the videotaped free play of 24, 3–4-year-olds, half of whom had disabilities, in four University-sponsored, inclusive, child-centered preschool classrooms. There were 7–10, 20-minute observations for each child. Despite significant differences related to child condition in the frequencies of interactions with peers and one-on-one with adults, the same pattern obtained for both groups: Across observations, the proportions of time that each child spent interacting with peers and with adults were negatively correlated for 21 of the 24 children. Analyses of event-sequences revealed that adults were more likely than expected by chance to initiate interactions with a child when s/he was alone and less likely to do so when s/he was interacting with a peer. Within-child patterns of choices also indicated that, after an adult had initiated an interaction with them, the children were less likely to initiate an interaction with a peer and more likely than expected to initiate another interaction with an adult. Additional, exploratory analyses yielded results consistent with the view that some kinds of exchanges with adults may interfere with peer interactions. Implications both for theory and for planning curricula are discussed.     

Being Mimicked Increases Prosocial Behavior in 18‐Month‐Old Infants

Most previous research on imitation in infancy has focused on infants' learning of instrumental actions on objects. This study focused instead on the more social side of imitation, testing whether being mimicked increases prosocial behavior in infants, as it does in adults (van Baaren, Holland, Kawakami, & van Knippenberg, 2004). Eighteen‐month‐old infants (N = 48) were either mimicked or not by an experimenter; then either that experimenter or a different adult needed help. Infants who had previously been mimicked were significantly more likely to help both adults than infants who had not been mimicked. Thus, even in infancy, mimicry has positive social consequences: It promotes a general prosocial orientation toward others.     

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.     

秋天的落叶

秋天的落叶落下来,落下来,落下来。 （由直立变为蹲下） 秋天的树叶在飞旋,在飞旋,在飞旋。 （站起并转圈） 秋天的树叶飘呀飘．飘呀飘,飘呀飘。 （左右摇晃身体）     

SEEK Web tutor: fostering a critical stance while exploring the causes of volcanic eruption

We investigated the impact of a Web tutor on college students’ critical stance and learning while exploring Web pages on science. Critical stance is an aspect of self-regulated learning that emphasizes the need to evaluate the truth and relevance of information as the learner engages in systematic inquiry to answer challenging questions. The Web tutor is called SEEK, an acronym for Source, Evidence, Explanation, and Knowledge. The SEEK Tutor was designed to promote a critical stance through several facilities in a computer environment: spoken hints on a mock Google™ search page, on-line ratings on the reliability of particular Web sites, and a structured note-taking facility that prompted them to reflect on the quality of particular Web sites. We conducted two experiments that trained students how to take a critical stance and that tracked their behavior while exploring Web pages on plate tectonics to research the causes of the volcanic eruption of Mt. St. Helens. The SEEK Tutor did improve critical stance, as manifested in essays on the causes of the volcanic eruption, and did yield learning gains for some categories of information (compared with comparison conditions). However, many measures were unaffected by either the presence of the SEEK Tutor or by prior training on critical stance. We anticipate that robust improvements on critical stance and learning will require more training and/or some expert feedback and interactive scaffolding of critical stance in the context of specific examples. This work was conducted while Tenaha O’Reilly was a postdoctoral fellow at the University of Memphis.     

Effects of infant sociability and the caretaking environment on infant cognitive performance.

40 middle-class mothers and their 12-month-old infants participated in an examination of the extent to which infant sociability and infant home experiences were correlated with cognitive capacity. Results indicated that the measures of the home environment (including Caldwell's Home Observation for Measurement of the Environment [HOME] inventory) were not correlated with the measures of cognitive competence (Bayley Mental Development Index [MDI], Ordinal Scales of Psychological Development) except among firstborns. Measures of the home environment were, however, correlated with measures of infant sociability (assessed inside and outside the test situation): sociable infants had sociable mothers. The infants' reactions to strange adults clearly influenced their performance in testing situations. Strong relationships were found between both measures of sociability and both measures of cognitive competence. The sociable friendly infants received higher scores on both cognitive tests than the less sociable babies did.     

Developmental Differences in Infant Attention to the Spectral Properties of Infant-directed Speech

Across several independent studies, infants from a few days to 9 months of age have shown preferences for infant-directed (ID) over adult-directed (AD) speech. Moreover, 4-month-olds have been shown to prefer sine-wave analogs of the fundamental frequency of ID speech, suggesting that exaggerated pitch contours are prepotent stimuli for infants. The possibility of similar preferences by 1-month-olds was examined in a series of experiments, using a fixation-based preference procedure. Results from the first 2 experiments showed that 1-month-olds did not prefer the lower-frequency pitch characteristics of ID speech, even though 1-month-olds were able to discriminate low-pass filtered ID and AD speech. Since low-pass filtering may have distorted the fundamental frequency characteristics of ID speech, 1-month-olds were also tested with sine-wave analogs of the fundamental frequencies of the ID utterances. Infants in this third experiment also showed no preference for ID pitch contours. In the fourth experiment, 1-month-olds preferred a natural recording of ID speech over a version which preserved only its lower frequency prosodic features. From these results, it is argued that, although young infants are similar to older infants in their attraction to ID speech, their preferences depend on a wider range of acoustic features (e.g., spectral structure). It is suggested that exaggerated pitch contours which characterize ID speech may become salient communicative signals for infants through language-rich, interactive experiences with caretakers and increased perceptual acuity over the first months after birth.     

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.     

The contribution of visual and inertial mechanisms to navigation in total darkness

Rats were trained in the Morris water maze to reach a platform in darkness after they had been provided with some information on their initial location. They were given trials with (1) the light on (light condition) and (2) light followed by darkness (dark condition). In this latter condition, the dark period was preceded by either a brief (short group) or a long (long group) initial light period. Although the rats in the short group first oriented accurately toward the platform, their trajectory rapidly deviated in darkness. In contrast, the rats in the long group were able to navigate accurately over a longer distance, but finally also deviated. In transfer trials, the rats in the short group were less accurate than the rats in the long group in the dark; however, both groups performed well in light. This suggests that navigation in darkness depends not only on the use of recent visual and locomotor memory but also on the activation of an inertia-based navigation process.