Electroencephalogram and heart rate measures of working memory at 5 and 10 months of age

We recorded electroencephalogram (EEG; 6-9 Hz) and heart rate (HR) from infants at 5 and 10 months of age during baseline and performance on the looking A-not-B task of infant working memory (WM). Longitudinal baseline-to-task comparisons revealed WM-related increases in EEG power (all electrodes) and EEG coherence (medial frontal-occipital electrode pairs) at both ages. WM-related decreases in HR were only present at 5 months, and WM-related increases in EEG coherence became more localized by 10 months. Regression analyses revealed that baseline-to-task changes in psychophysiology accounted for variability in WM performance at 10 but not 5 months. HR and EEG power (medial frontal and lateral frontal electrodes) were unique predictors of variability in 10-month WM performance. These findings are discussed in relation to frontal lobe development and represent the first comprehensive longitudinal analysis of age-related changes in the behavioral and psychophysiological correlates of WM.     

Infant sleep moderates the effect of infant temperament on maternal depressive symptoms,maternal sensitivity,and family functioning

Observed infant temperamental difficulty and infant sleep efficiency and sleep variability were examined as predictors of maternal depressive symptoms, maternal sensitivity, and family functioning. Eight observations at 8-months postpartum were used to assess infant temperament, and actigraphy was used to measure infant sleep for 1-week at the time of the 8-month assessment. Structured clinical interviews were used to assess maternal depressive symptoms between 5 and 12 months postpartum and at 15 months postpartum, and observational assessments were used to assess maternal sensitivity and family functioning at 15 months postpartum. Variability in infant sleep moderated the effect of infant temperament on maternal depressive symptoms, maternal sensitivity, and family functioning. Infant temperament was positively associated with maternal depressive symptoms when variability in infant sleep efficiency was high, but not when variability in infant sleep efficiency was low. Likewise, infant temperament was negatively associated with maternal sensitivity and family functioning when variability in infant sleep efficiency was high, but not when variability in infant sleep efficiency was low. Results underscore the importance of infant sleep for maternal and family health.     

Force and timing variability in rhythmic unimanual tapping

In 3 experiments the interdependencies between timing and force production in unimanual paced and self-paced rhythmic tapping tasks were examined as participants (N = 6 in each experiment) tapped (a) to 1 of 3 target periods (333 ms, 500 ms, and 1,000 ms), while they simultaneously produced a constant peak force (PF) over a 50-s trial; (b) to produce 1 of 3 target forces (5, 10, and 15 N) at their preferred frequency, while keeping their rhythm as invariant as possible; and (c) to all combinations of target force and period. The results showed that (a) magnitudes of force and period were largely independent; (b) variability in timing increased proportionally with tapping period, and the variability in force increased with peak force; (c) force variability decreased at faster tapping rates; and (d) timing variability decreased with increasing force levels. (e) Analysis of tap-to-tap variability revealed adjustments over sequences of taps and an acceleration in the tapping rate in unpaced conditions. The interdependencies of force and time are discussed with respect to the challenges they provide for an oscillator-based account.     

Force and Timing Variability in Rhythmic Unimanual Tapping

In 3 experiments the interdependencies between timing and force production in unimanual paced and self-paced rhythmic tapping tasks were examined as participants (N = 6 in each experiment) tapped (a) to 1 of 3 target periods (333 ms, 500 ms, and 1,000 ms), while they simultaneously produced a constant peak force (PF) over a 50-s trial; (b) to produce 1 of 3 target forces (5, 10, and 15 N) at their preferred frequency, while keeping their rhythm as invariant as possible; and (c) to all combinations of target force and period. The results showed that (a) magnitudes of force and period were largely independent; (b) variability in timing increased proportionally with tapping period, and the variability in force increased with peak force; (c) force variability decreased at faster tapping rates; and (d) timing variability decreased with increasing force levels, (e) Analysis of tap-to-tap variability revealed adjustments over sequences of taps and an acceleration in the tapping rate in unpaced conditions. The interdependencies of force and time are discussed with respect to the challenges they provide for an oscillator-based account.     

Developmental differences in children's ballistic aiming movements of the arm

An experiment was conducted to examine the change in the relation between programming and "on-line" correction as a developmental explanation of children's arm movement performance. Each of 54 children in three age groups (5, 8, and 10 yr.) completed two types of rapid aiming arm movements in the longitudinal plane on the surface of a digitizer. Percent primary submovements and timing variability were dependent variables. Analysis suggested that the 5-yr.-olds used "on-line" monitoring during the arm movement and did not perform the movement sequence as a functional unit. Compared with 8- and 10-yr.-olds, the 5-yr.-olds planned a smaller portion of movements, executed the arm movements with more variability in time to peak velocity. The 8- and 10-yr.-olds appeared to plan their movements and execute the sequence as a unit. The developmental implications were discussed.     

Variability in the early development of visual self-recognition

A study was conducted to evaluate the (1) developmental course and (2) the temporal sequencing of visual (mirror, photo) and verbal (personal pronoun use) measures of self-recognition as well as the ability to locate a toy from its mirror image in relation to the child's own mirror image. A microgenetic approach was adopted to assess 10 toddlers biweekly between 15 and 23 months of age and for comparison, a cross-section of children tested once across the same age range. Longitudinal data indicated that visual self-recognition emerged gradually and showed wide variability in expression prior to becoming stable, a finding masked in the cross-sectional data where performance appeared to improve abruptly. Both cross-sectional and longitudinal data confirmed that mirror self-recognition was the earliest precursor of the indices of self-recognition to emerge followed by the use of personal pronouns and photo identification. Implications for the emergence and integration of the self are discussed.     

EVALUATION OF AN INPATIENT PROGRAM AIMED AT PREPARING “HARD-TO-PLACE” CHRONICALLY MENTALLY ILL FOR THE COMMUNITY

A program designed to prepare long-stay “hard-to-place” psychiatric inpatients for successful community placement was evaluated. Fifteen patients in the Intensive Learning Center (ILC) program were assessed at 5- and 10-month intervals following baseline. In addition, their functioning was compared to a criterion related comparison group of 26 patients who had been transferred to community placements 18 months earlier. Two informant driven measures were used: The Rehabilitation Evaluation of Hall and Baker (REHAB), (Baker & Hall, 1988) and, Adaptive Behavior Scale (ABS), (Nihira, Foster, Shellhaas, & Leland, 1975). The results indicated significant improvement in the ILC patients adaptive functioning after 5 months, but this improvement was not consistently sustained at the 10 month follow-up. Comparisons between the ILC and community groups were made at 10 months and suggested considerable overlap in functioning between the two groups. The implications of the findings for program development and implementation as well as for discharge planning are discussed.     

The role of maternal affect attunement in dyadic and triadic communication

The influence of maternal affect attunement on the relationship between gaze monitoring during dyadic communication at 3 months and coordinated attention during triadic communication at 5, 7 and 10 months was examined in a longitudinal study. Although most infants engaged in gaze monitoring at 3 months and in coordinated attention at 5, 7 and 10 months, a regression analysis revealed that gaze monitoring at 3 months significantly predicted coordinated attention at 10 months only when maternal affect attunement was high. These findings are discussed in terms of theories that emphasize the role of social interaction in the development of meaningful communication and continuity in mental state awareness during the first year of life.     

Speed-accuracy characteristics of saccadic eye movements

Speed-accuracy trade-off characteristic of horizontal saccadic eye movements were examined in this study. Unlike limb movements, saccadic eye movements are preprogrammed, unidimensional, and do not involve target impact. Hence, they provide an optimal test of the impulse variability account of the speed-accuracy trade-off in rapid movements. Subjects were required to alternately look at two target lights as fast and as accurately as possible for a period of 10 s. Target lights subtended angles of 5, 10, 15, and 20 degrees. By restricting target distances to less than 20 degrees of arc, the speed-accuracy relation was examined for single horizontal saccadic movements of the eye. movement of the dominant eye was tracked with an infra-red eye monitoring device. Fifty saccadic movements of the eye were recorded for each target distance and used to compute the average amplitude, duration, and velocity of eye movements, as well as, movement endpoint variability. An increase in both average velocity and movement endpoint variability with increasing movement amplitude was found. This, together with the unique features of the eye movement system, support the impulse variability account of the speed-accuracy trade-off in rapid movements.     

Changes in the structure of children's isometric force variability with practice

This study examined the effect of age and practice on the structure of children's force variability to test the information processing hypothesis that a reduction of sensorimotor system noise accounts in large part for age-related reductions in perceptual-motor performance variability. In the study, 6-year-olds, 10-year-olds, and young adults practiced on 5 consecutive days (15 trials/day), maintaining for 15-s trials a constant level of force (5 or 25% of maximum voluntary contraction) against an object using a pinch grip (thumb and index finger). With increasing age, the amount of force error and variability decreased, but the sequential structure of variability increased in irregularity. With practice, children reduced the amount of variability by changing the structure of the force output so as to be more similar to that of their older counterparts. The findings provide further evidence that practice-driven changes in the structure of force output, rather than a decline in the amount of white noise, largely account for age-related reductions in the amount of force variability.     

Variability in parenting behaviours during play and during mealtimes with toddlers

Few empirical studies have explored variability in parenting behaviours observed in a mealtime setting as well as in a play setting with young children. We analysed data from 282 parent–toddler dyads who participated in the Play & Grow study in the United States in 2017–2019. Parent–child interactions were video recorded during play in the laboratory when the child was 18 months old and then during mealtime in the home 6 months later. Standardised coding procedures were used to rate parenting behaviours (sensitivity, cognitive stimulation, positive regard, detachment, intrusive control and negative regard). We describe correlations and differences and variability in parenting behaviour between the two assessments and relative to child sex, gestational age, parent education level, household composition and household income. Detachment was lower on average during play at 18 months compared to during mealtime at 24 months (Cohen's d = −0.40), and the other five parenting behaviours were greater on average during play than during mealtime (d = 0.18–0.43). Sociodemographic characteristics were unrelated to the magnitude of individual differences across contexts in any of the parenting behaviours. Implications for research on associations between parent–child interactions and risk for childhood obesity are discussed.     

Dynamic instability of visuospatial images

Five experiments using a visuospatial task were conducted to study memory accuracy and variability and to identify the origin of variations in steady states. This research was conducted from a dynamical perspective, that is, by analyzing the temporal course of discrepancies between the perceptual configuration and its memory (accuracy) and the temporal course of discrepancies between 2 successive memories (variability). In Experiment 1 the stimulus (12 black dots randomly disposed) was presented repeatedly to assess the general evolution of accuracy and variability. In Experiments 2 and 3 memory accuracy and memory variability were separated to identify their relationship. In Experiments 4 and 5 memory variability was studied to determinate the origin of steady state variations. Results show that memory accuracy and memory variability evolved independently and that memory variability reached a threshold that was subject-dependent. The dynamic properties of image construction and stability are discussed.     

Development of hand preferences in marmosets (Callithrix jacchus) and effects of aging

The authors investigated the development of unimanual hand use and hand preferences during feeding in 15 marmosets (Callithrix jacchus), ages birth to 51-70 months. Bimanual hand use was common at 1-2 months, but by 5-8 months unimanual holding had developed and so had significant hand preferences. Half of the marmosets preferred to pick up and take food to the mouth with the left hand, and half preferred the right hand. Individuals maintained the same hand preference at all ages examined. Significant relationships were also found between the postures adopted during feeding and the direction of hand preferences displayed by juvenile marmosets. There was a positive correlation between increased suspension and increased left-hand preference, and a negative correlation between increased feeding in a tripedal posture and increased left-hand preference. These results are discussed in terms of motor development and hemispheric specialization.     

Variability and its sources in infant categorization

Variability of infants’ categorization performance and potential sources of this variability were investigated. Using data from 13 categorization studies employing a habituation-of-looking paradigm with infants 3, 5, 6, and 9 months of age, a method for establishing a categorization criterion was developed and then used to classify individual infants as “categorizers” for particular tasks. Logistic regression analyses were then used to identify demographic and information-processing variables that predicted “categorizer” classification. Variables that increased the odds of being classified as a categorizer were gender, number of habituation trials, and duration of peak look during habituation; total looking time during habituation decreased the odds of categorizer classification. These findings are discussed in the context of individual differences in information processing.     

Changes in Academic Engaged Time as a Function of Assessment and Special Education Intervention

Four students were observed systematically at the time when they were referred to special education, and again one month and two months after placement in special education, to examine changes in the nature of instruction received and the students' academic responding times as a function of special education intervention. At each observation time, data were recorded for two full school days on 11 instructional variables and 19 student response variables in 10-second intervals. Considerable variability was evident among students in the amount of time accademic instruction was allocated to them and in the amount of time in which they engaged in academic responding. Changes in instruction and student responding as a function of special education intervention were inconsistent across students. Implications for special education policies are discussed.     

The Baby and Toddler Behavior Questionnaires: Empirical studies and conceptual considerations

The article discusses the conceptual basis of two parental questionnaires, each measuring six dimensions of infant behavior differences and developed on large representative samples of Swedish infants, aged 3 to 10 months ( N=791 ) and 11 to 15 months ( N =357). Empirical validation data are presented and discussed as well as evidence for a constitutional basis for some dimensions. A second order variable identified in the older age group is suggested to be related to the construct of difficult temperatment. Finally, suggestions for use of the two questionnaires are put forward.     

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.     

Using Gesture and Speech to Capture Transitions in Learning

The present study compared 3 measures of knowledge variability to determine which measure predicts learning. Eighty-six children between the ages of 5 and 8 years participated in a pretest-training–posttest study of conservation understanding. Gesture-speech mismatches predicted learning better than both an across-task measure and a within-task measure of variability in speech explanations of conservation. This suggests that transitional knowledge may be best characterized as the simultaneous activation of multiple representations distributed across modalities. Implications for how gesture-speech mismatches may elucidate mechanisms underlying cognitive change are discussed.     

Effects of varying force production in practice schedules of children learning a discrete motor task

The variability of practice prediction from Schmidt's Schema Theory involving transfer and retention was tested when manipulating only the performance parameter of over-all force. Children (n = 120) of two age groups performed a 15-in (39.1 cm) arm movement on a linear slide modified to allow manipulating the force required to move the car on the slide. No significant differences between the variable group and the constant practice group were found for either the 10 transfer or 5 retention trials. Mean absolute errors were ordered in favor of the constant practice group for both transfer and retention. For the first transfer trial a significant difference was found; constant practice groups performed better. This finding is contrary to predictions of schema theory as well as evidence from children as subjects.     

Television viewing and the learning of sex-role stereotypes

This study was designed to determine the relationship between the amount of time children spend watching television and their knowledge of adult sex-role stereotypes. Males and females in grades 1, 3, 5, and 7 who were classified as heavy television viewers (25 or more hours per week) or light viewers (10 or less hours per week) both at the time of the study and 15 months previously were administered the Sex Stereotype Measure, an instrument designed to determine children's awareness of stereotyped sex-role perceptions held by adults. Heavy viewers were found to have more stereotyped perceptions than light viewers. A significant interaction effect indicated that among low viewers the perception of male stereotypes steadily declines with increasing age; among heavy viewers, stereotypic responses to male items are maintained with increasing age. No comparable interaction effect was obtained for perception of female stereotypes. The role of interaction with live models in breaking down stereotypic perceptions of males is discussed.A modified version of this paper was presented at the meeting of the Society for Research in Child Development, Denver, April 1975.