Individual differences in dynamic measures of verbal learning abilities in young twin pairs and their older siblings

Boy-Girl Differences in Pictorial Verbal Learning in Students Aged 8-12 Years and the Influence of Parental Education

This large-scale cross-sectional study of schoolchildren aged 8–12 years (N = 152) evaluates two factors which potentially determine individual differences in intentional learning: the child’s sex and parental education. Intentional learning was assessed with a newly constructed Pictorial Verbal Learning Task (PVLT). This task presents line drawings of concrete objects as to-be-remembered information instead of written or auditory presented words. The PVLT has the advantage that performance is not confounded by individual differences in reading or hearing abilities. Results revealed clear sex differences in performance: Girls outperformed boys. Parental education also contributed to individual differences in performance since children of higher educated parents outperformed children of lower educated parents. The results therefore suggest that both sex and parental education could be potent contributors to individual differences in learning performance at school. The findings more specifically imply that children of less educated parents and boys need additional guidance and support in intentional learning when new information and procedures are presented for the first time.

Shiraz Verbal Learning Test (SVLT): Normative Data for Neurologically Intact Speakers of Persian

Objective

Memory assessment plays an important role in the diagnosis of neurodegenerative disorders. Several tests, such as the California Verbal Learning Test (CVLT), have been developed for this purpose, yet a variety of different factors can affect one's performance on such tests, the most important of which are demographic and cultural variables. The present study examined the norming process performed on the CVLT-revised and aimed to devise a new test, the Shiraz Verbal Learning Test (SVLT), to better meet the needs of speakers of Persian.

Method

In order to collect normative data, a group of 1275 Persian-speaking individuals consisting of both sexes (676 women and 599 men) aged 20-89 years old were selected for this study.

Results

The results of Pearson's Correlation analysis indicated that there was a significant negative correlation between age and SVLT performance and a positive one between education and SVLT performance (p < .001) among the whole sample. Moreover, between-group analyses showed that the female participants performed significantly better than their male counterparts on nearly all subtests (Total Trails 1-5, Short-Delay Free Recall, Short-Delay Cued Recall, Long-Delay Free Recall, Long-Delay Cued Recall, and Total Learning Slope), with the only exception being Long-Delay Yes/No Recognition.

Conclusions

These results suggest that the SVLT has the potential to be further developed among different culture and language groups. This test can also be used for clinical and research purposes for patients with neuropsychiatric disorders who need further neuropsychological assessment.

Brain SCALE: brain structure and cognition: an adolescent longitudinal twin study into the genetic etiology of individual differences

From childhood into adolescence, the child's brain undergoes considerable changes in both structure and function. Twin studies are of great value to explore to what extent genetic and environmental factors explain individual differences in brain development and cognition. In The Netherlands, we initiated a longitudinal study in which twins, their siblings and their parents are assessed at three year intervals. The participants were recruited from The Netherlands Twin Register (NTR) and at baseline consisted of 112 families, with 9-year-old twins and an older sibling. Three years later, 89 families returned for follow-up assessment. Data collection included psychometric IQ tests, a comprehensive neuropsychological testing protocol, and parental and self-ratings of behavioral and emotional problems. Physical maturation was measured through assessment of Tanner stages. Hormonal levels (cortisol, luteinizing hormone, follicle-stimulating hormone, testosterone, and estrogens) were assessed in urine and saliva. Brain scans were acquired using 1.5 Tesla Magnetic Resonance Imaging (MRI), which provided volumetric measures and measures of cortical thickness. Buccal swabs were collected for DNA isolation for future candidate gene and genome-wide analysis studies. This article gives an overview of the study and the main findings. Participants will return for a third assessment when the twins are around 16 years old. Longitudinal twin-sibling studies that map brain development and cognitive function at well-defined ages aid in the understanding of genetic influences on normative brain development.