The coupling of head,reach and grasp movement in nine months old infant prehension

In 9-month-old-infants adjustments in the reaching pattern to sudden changes in object location were examined. An attractive ball was presented to the infants at their midline and on some trials (perturbation trials) the ball suddenly changed position 15 cm to the right or left during the reach. For the perturbed trials the movement times approximately doubled compared to the control trials and significantly fewer balls were grasped. The results indicate that infants need to finish the first movement before being able to redirect the reach to a new destination. The correlation between the latency of the head and hand adjustment to the perturbation were 0.85 and 0.78 for movements to the left and to the right, respectively, indicating a tight coupling. The time between the start of the perturbation and peak velocity (TPPV) was significantly shorter for the head movement than for the hand movement, indicating that the head is leading the hand.     

A least squares algorithm for fitting additive trees to proximity data

A least squares algorithm for fitting additive trees to proximity data is described. The algorithm uses a penalty function to enforce the four point condition on the estimated path length distances. The algorithm is evaluated in a small Monte Carlo study. Finally, an illustrative application is presented.The author is Aspirant of the Belgian Nationaal Fonds voor Wetenschappelijk Onderzoek. The author is indebted to Professor J. Hoste for providing computer facilities at the Institute of Nuclear Sciences at Ghent.     

A Mixed Model to Disentangle Variance and Serial Autocorrelation in Affective Instability Using Ecological Momentary Assessment Data

Affective instability, the tendency to experience emotions that fluctuate frequently and intensively over time, is a core feature of several mental disorders including borderline personality disorder. Currently, affect is often measured with Ecological Momentary Assessment protocols, which yield the possibility to quantify the instability of affect over time. A number of linear mixed models are proposed to examine (diagnostic) group differences in affective instability. The models contribute to the existing literature by estimating simultaneously both the variance and serial dependency component of affective instability when observations are unequally spaced in time with the serial autocorrelation (or emotional inertia) declining as a function of the time interval between observations. In addition, the models can eliminate systematic trends, take between subject differences into account and test for (diagnostic) group differences in serial autocorrelation, short-term as well as long-term affective variability. The usefulness of the models is illustrated in a study on diagnostic group differences in affective instability in the domain of eating disorders. Limitations of the model are that they pertain to group (and not individual) differences and do not focus explicitly on circadian rhythms or cycles in affect.     

WordGen: A tool for word selection and nonword generation in Dutch,English, German,and French

WordGen is an easy-to-use program that uses the CELEX and Lexique lexical databases for word selection and nonword generation in Dutch, English, German, and French. Items can be generated in these four languages, specifying any combination of seven linguistic constraints: number of letters, neighborhood size, frequency, summated position-nonspecific bigram frequency, minimum position-nonspecific bigram frequency, position-specific frequency of the initial and final bigram, and orthographic relatedness. The program also has a module to calculate the respective values of these variables for items that have already been constructed, either with the program or taken from earlier studies. Stimulus queries can be entered through WordGen’s graphical user interface or by means of batch files. WordGen is especially useful for (1) Dutch and German item generation, because no such stimulus-selection tool exists for these languages, (2) the generation of nonwords for all four languages, because our program has some important advantages over previous nonword generation approaches, and (3) psycholinguistic experiments on bilingualism, because the possibility of using the same tool for different languages increases the cross-linguistic comparability of the generated item lists. WordGen is free and available athttp://expsy.ugent.be/wordgen.htm.     

Differential ability and attainment in language and arithmetic of Dutch primary school pupils

Background . In preschool and primary education, pupils differ in many abilities and competences (giftedness). Yet mainstream educational practice seems rather homogeneous in providing age‐based or grade–class subject matter approaches. Aims . To clarify whether pupils scoring initially at high ability level do develop and attain differently at school with respect to language and arithmetic compared with those displaying other initial ability levels. To investigate whether specific individual, family, or educational variables covary with the attainment of these different types of pupils in school. Samples . Data from the large‐scale PRIMA cohort study including a total of 8,258 Grades 2 and 4 pupils from 438 primary schools in The Netherlands. Methods . Secondary analyses were carried out to construct gain scores for both language and arithmetic proficiency and a number of behavioural, attitudinal, family, and educational characteristics. The pupils were grouped into four different ability categories (highly able, able, above average, average or below average). Further analyses used Pearson correlations and analyses of variance both between‐ and within‐ability categories. Cross‐validation was done by introducing a cohort of younger pupils in preschool and grouping both cohorts into decile groups based on initial ability in language and arithmetic. Results . Highly able pupils generally decreased in attainment in both language and arithmetic, whereas pupils in average and below‐average groups improved their language and arithmetic scores. Only with highly able pupils were some educational characteristics correlated with the pupils' development in achievement, behaviour, and attitudes. Conclusions . Preschool and primary education should better match pupils' differences in abilities and competences from their start in preschool to improve their functioning, learning processes, and outcomes. Recommendations for educational improvement strategies are presented at the end of the article.     

Parenting style as a mediator between children's negative emotionality and problematic behavior in early childhood

Negative emotionality is considered to be the core of the difficult temperament concept (J. E. Bates, 1989; R. L. Shiner, 1998). In this correlational study, the authors examined whether the relations between children's negative emotionality and problematic behavior (internalizing and externalizing) were partially mediated by parenting style (authoritative and authoritarian) in a community sample of 196 3-year-old children and their mothers. The authors assessed maternal perception of child negative emotionality using the Children's Behavior Questionnaire (M. K. Rothbart, S. A. Ahadi, K. L. Hershey, & P. Fisher, 2001) and assessed problematic child behavior by means of maternal report using the Child Behavior Checklist (T. M. Achenbach, 1992). The results showed that the relations between child negative emotionality and internalizing and externalizing behaviors were partially mediated by mothers' authoritative parenting style. Moreover, when the authors used confirmatory factor analysis to decontaminate possible overlap in item content between measures assessing temperament and problematic behavior, the association between negative emotionality and internalizing behavior was fully mediated by authoritative parenting.     

Does Mastery of ABLA Level 6 Make it Easier for Individuals with Developmental Disabilities to Learn to Name Objects?

Level 6 of the Assessment of Basic Learning Abilities (ABLA) assesses the ease or difficulty with which persons with developmental disabilities are able to learn a two-choice auditory-visual discrimination. We investigated whether participants who passed ABLA Level 6 (Group 1) would more readily learn object naming (vocal tacts) than those who failed ABLA Level 6 (Group 2). The groups were matched on the Communication Subscale of the Vineland Adaptive Behavior Scale. Results indicated that Group 1 met mastery criterion for a significantly larger number of naming responses and in significantly fewer trials than Group 2. The implications for language training are discussed.     

Reliability of a Longitudinal Sequence of Scale Ratings

Reliability captures the influence of error on a measurement and, in the classical setting, is defined as one minus the ratio of the error variance to the total variance. Laenen, Alonso, and Molenberghs (Psychometrika 73:443–448, 2007) proposed an axiomatic definition of reliability and introduced the R _T coefficient, a measure of reliability extending the classical approach to a more general longitudinal scenario. The R _T coefficient can be interpreted as the average reliability over different time points and can also be calculated for each time point separately. In this paper, we introduce a new and complementary measure, the so-called R _Λ , which implies a new way of thinking about reliability. In a longitudinal context, each measurement brings additional knowledge and leads to more reliable information. The R _Λ captures this intuitive idea and expresses the reliability of the entire longitudinal sequence, in contrast to an average or occasion-specific measure. We study the measure’s properties using both theoretical arguments and simulations, establish its connections with previous proposals, and elucidate its performance in a real case study. The authors are grateful to J&J PRD for kind permission to use their data. We gratefully acknowledge support from Belgian IUAP/PAI network “Statistical Techniques and Modeling for Complex Substantive Questions with Complex Data.”