Minding the gap: Children's difficulty conceptualizing spatial intervals as linear measurement units.

Understanding measurement units is critical to mathematics and science learning, but it is a topic that American students find difficult. In 3 studies, we investigated the challenges underlying this difficulty in kindergarten and second grade by comparing performance on different versions of a linear measurement task. Children measured crayons that were either aligned or shifted relative to the left edge of either a continuous ruler or a row of discrete units.

Heterozygote carriers for CNVs in PARK2 are at increased risk of Parkinson's disease.

Together with point mutations, homozygous deletions or duplications in PARK2 are responsible for the majority of autosomal recessive juvenile Parkinsonism. It is debated, however, whether heterozygous carriers of these mutations are at increased risk of Parkinson's disease (PD). Our goal was to determine whether heterozygous carriers of copy number variants (CNVs) affecting exons of the PARK2 gene are at risk of PD that is greater than that of non-carriers.

Spinocerebellar ataxia type 36 exists in diverse populations and can be caused by a short hexanucleotide GGCCTG repeat expansion.

Objective: Spinocerebellar ataxia 36 (SCA36) is an autosomal-dominant neurodegenerative disorder caused by a large (>650) hexanucleotide GGCCTG repeat expansion in the first intron of the NOP56 gene. The aim of this study is to clarify the prevalence, clinical and genetic features of SCA36.

Methods: The expansion was tested in 676 unrelated SCA index cases and 727 controls from France, Germany and Japan.

EIF4G1 is neither a strong nor a common risk factor for Parkinson's disease: evidence from large European cohorts.

Background: Missense mutations in the eukaryotic translation initiation factor 4-γ 1 (EIF4G1) gene have previously been implicated in familial Parkinson's disease (PD). A large PD family with autosomal-dominant segregation showed a heterozygous missense mutation and additional patients were found to have unique sequence variants that have not been observed in controls. Subsequent studies have reported contradictory findings.

New evidence about language and cognitive development based on a longitudinal study: hypotheses for intervention.

We review findings from a four-year longitudinal study of language learning conducted on two samples: a sample of typically developing children whose parents vary substantially in socioeconomic status, and a sample of children with pre- or perinatal brain injury. This design enables us to study language development across a wide range of language learning environments and a wide range of language learners. We videotaped samples of children's and parents' speech and gestures during spontaneous interactions at home every four months, and then we transcribed and coded the tapes.

25 years of research on the use of geometry in spatial reorientation: a current theoretical perspective.

The purpose of this article is to review and evaluate the range of theories proposed to explain findings on the use of geometry in reorientation. We consider five key approaches and models associated with them and, in the course of reviewing each approach, five key issues. First, we take up modularity theory itself, as recently revised by Lee and Spelke (Cognitive Psychology, 61, 152-176, 2010a; Experimental Brain Research, 206, 179-188, 2010b).

Common variant at 16p11.2 conferring risk of psychosis.

Epidemiological and genetic data support the notion that schizophrenia and bipolar disorder share genetic risk factors. In our previous genome-wide association study, meta-analysis and follow-up (totaling as many as 18 206 cases and 42 536 controls), we identified four loci showing genome-wide significant association with schizophrenia. Here we consider a mixed schizophrenia and bipolar disorder (psychosis) phenotype (addition of 7469 bipolar disorder cases, 1535 schizophrenia cases, 333 other psychosis cases, 808 unaffected family members and 46 160 controls).

Variant of TREM2 associated with the risk of Alzheimer's disease.

Background: Sequence variants, including the ε4 allele of apolipoprotein E, have been associated with the risk of the common late-onset form of Alzheimer's disease. Few rare variants affecting the risk of late-onset Alzheimer's disease have been found.

Methods: We obtained the genome sequences of 2261 Icelanders and identified sequence variants that were likely to affect protein function.

A mutation in APP protects against Alzheimer's disease and age-related cognitive decline.

The prevalence of dementia in the Western world in people over the age of 60 has been estimated to be greater than 5%, about two-thirds of which are due to Alzheimer's disease. The age-specific prevalence of Alzheimer's disease nearly doubles every 5 years after age 65, leading to a prevalence of greater than 25% in those over the age of 90 (ref. 3).

Early puzzle play: a predictor of preschoolers' spatial transformation skill.

Individual differences in spatial skill emerge prior to kindergarten entry. However, little is known about the early experiences that may contribute to these differences. The current study examined the relation between children's early puzzle play and their spatial skill.

Children's spatial thinking: does talk about the spatial world matter?

In this paper we examine the relations between parent spatial language input, children's own production of spatial language, and children's later spatial abilities. Using a longitudinal study design, we coded the use of spatial language (i.e.

Early sex differences in weighting geometric cues.

When geometric and non-geometric information are both available for specifying location, men have been shown to rely more heavily on geometry compared to women. To shed insight on the nature and developmental origins of this sex difference, we examined how 18- to 24-month-olds represented the geometry of a surrounding (rectangular) space when direct non-geometric information (i.e.

Common variants at VRK2 and TCF4 conferring risk of schizophrenia.

Common sequence variants have recently joined rare structural polymorphisms as genetic factors with strong evidence for association with schizophrenia. Here we extend our previous genome-wide association study and meta-analysis (totalling 7 946 cases and 19 036 controls) by examining an expanded set of variants using an enlarged follow-up sample (up to 10 260 cases and 23 500 controls). In addition to previously reported alleles in the major histocompatibility complex region, near neurogranin (NRGN) and in an intron of transcription factor 4 (TCF4), we find two novel variants showing genome-wide significant association: rs2312147[C], upstream of vaccinia-related kinase 2 (VRK2) [odds ratio (OR) = 1.

Sources of variability in children's language growth.

The present longitudinal study examines the role of caregiver speech in language development, especially syntactic development, using 47 parent-child pairs of diverse SES background from 14 to 46 months. We assess the diversity (variety) of words and syntactic structures produced by caregivers and children. We use lagged correlations to examine language growth and its relation to caregiver speech.

What counts in the development of young children's number knowledge?

Prior studies indicate that children vary widely in their mathematical knowledge by the time they enter preschool and that this variation predicts levels of achievement in elementary school. In a longitudinal study of a diverse sample of 44 preschool children, we examined the extent to which their understanding of the cardinal meanings of the number words (e.g.

Category effects on stimulus estimation: shifting and skewed frequency distributions.

The category adjustment model (CAM) proposes that estimates of inexactly remembered stimuli are adjusted toward the central value of the category of which the stimuli are members. Adjusting estimates toward the average value of all category instances, properly weighted for memory uncertainty, maximizes the average accuracy of estimates. Thus far, the CAM has been tested only with symmetrical category distributions in which the central stimulus value is also the mean.

Location representation in enclosed spaces: what types of information afford young children an advantage?

It has been suggested that young children can only reorient, locating a target object, when the geometry of an enclosed space provides distinctive shape information [e.g., Hermer, L.

Coding location: the view from toddler studies.

The ability to locate objects in the environment is adaptively important for mobile organisms. Research on location coding reveals that even toddlers have considerable spatial skill. Important information has been obtained using a disorientation task in which children watch a target object being hidden and are then blindfolded and rotated so they cannot track their changing relation to the target.

Development of proportional reasoning: where young children go wrong.

Previous studies have found that children have difficulty solving proportional reasoning problems involving discrete units until 10 to 12 years of age, but can solve parallel problems involving continuous quantities by 6 years of age. The present studies examine where children go wrong in processing proportions that involve discrete quantities. A computerized proportional equivalence choice task was administered to kindergartners through 4th-graders in Study 1, and to 1st- and 3rd-graders in Study 2.

Priming a perspective in Spanish monolingual children: the use of syntactic alternatives.

We used a syntactic priming paradigm to show priming effects for active and passive forms in monolingual Spanish-speaking four- and five-year-olds. In a baseline experiment, we examined children's use of the fue-passive form and found it was virtually non-existent in their speech, although they produced important elements of the form. Children used a more frequent Spanish passive form, the subjectless/se-passive.

The Representation of Geometric Cues in Infancy.

There is evidence that, from an early age, humans are sensitive to spatial information such as simple landmarks and the size of objects. This study concerns the ability to represent a particular kind of spatial information, namely, the geometry of an enclosed layout-an ability present in older children, adults, and nonhuman animals (e.g.

Emergence of syntax: commonalities and differences across children.

This paper presents the results of a longitudinal examination of syntactic skills, starting at the age of emergence of simple sentences and continuing through the emergence of complex sentences. We ask whether there is systematic variability among children from different socioeconomic backgrounds in the early stages of sentence production. The results suggest a different answer for simple versus complex sentences.

Redirective labels and early vocabulary development.

Parents' object labels can be distinguished by whether the child is already attending to the object (follow-in) or not (lead-in). Lead-in labels have been found to be associated with low vocabulary. The current study examines whether the relation between lead-in labels and child vocabulary is influenced by whether the child's attention is redirected.