The Flynn effect (rising intelligence test performance in the general population over time and generations) varies enigmatically across countries and intelligence domains; its substantive meaning and causes remain elusive. This first formal meta-analysis on the topic revealed worldwide IQ gains across more than one century (1909-2013), based on 271 independent samples, totaling almost 4 million participants, from 31 countries. Key findings include that IQ gains vary according to domain (estimated 0.41, 0.30, 0.28, and 0.21 IQ points annually for fluid, spatial, full-scale, and crystallized IQ test performance, respectively), are stronger for adults than children, and have decreased in more recent decades. Altogether, these findings narrow down proposed theories and candidate factors presumably accounting for the Flynn effect. Factors associated with life history speed seem mainly responsible for the Flynn effect's general trajectory, whereas favorable social multiplier effects and effects related to economic prosperity appear to be responsible for observed differences of the Flynn effect across intelligence domains.

One Century of Global IQ Gains: A Formal Meta-Analysis of the Flynn Effect (1909–2013)

Objective: Early detection of children with developmental delay is crucial for determining which children require close surveillance and intervention services. For many decades, the Bayley Scales has been the most widely used objective measure of early developmental delay, both in clinical and research settings. Significant structural changes were incorporated in the most recent edition, the Bayley Scales of Infant and Toddler Development, Third Edition (Bayley-III). This article reviews the psychometric properties of the Bayley-III and investigates criticisms raised on the Bayley-III, namely that it overestimates developmental status and is a poor predictor of later functioning. Method: This critical review examines the literature on the Bayley-III, which was released in 2006. Results: The Cognitive, Language, and Motor composites of the Bayley-III overestimate development, resulting in an under-identification of children with developmental delay. A range of strategies have been proposed for deal...

Assessing developmental delay in early childhood — concerns with the Bayley-III scales

Adaptive Behavior Assessment System–Second Edition

A psychometric study of the Bayley Scales of Infant and Toddler Development - 3rd Edition for term and preterm Taiwanese infants

The interrelationships between motor, cognitive, and language development in children with and without intellectual and developmental disabilities

In response to concerns that the Bayley Scales of Infant and Toddler Development III (BSIDIII) underestimate delay in clinical populations, this study explores developmental quotient scores as an alternative to composite scores for these children. One hundred and twenty-two children aged ≤42 months, referred for diagnosis of developmental disability from January 2007 to May 2010, were assessed, and their composite and developmental quotient scores on each scale were compared. Composite scores identified only 22% (cognitive), 27% (motor), and 47.5% (language) of children as having a developmental disability. Developmental quotient scores were significantly lower than composite scores, giving rates of developmental disability of 56.6% (cognitive), 48.4% (motor), and 74.6% (language) and more closely matching both clinical impressions of delay and the proportions of those children who were also delayed on standardized tests of adaptive function.

The Use of the Bayley Scales of Infant and Toddler Development III with Clinical Populations: A Preliminary Exploration

Aim
The study aims to describe the developmental and behavioural difficulties in pre-school children who have experienced maltreatment and/or neglect

Methods
A retrospective medical file audit of all children assessed at the Cottage Family Care Centre, a child protection pre-school, between April 2004 and June 2010. Demographic characteristics, parent and teacher reports, and clinical and developmental assessment results were collated and analysed.

Results
The average age of the 55 children assessed was 36.3 months (ranging from 14 to 55.3 months). Fifty-five per cent were male and 65% were from disadvantaged families. A significant developmental delay in at least one domain and or a significant behavioural problem was identified in 91% of assessments. Overall (or global) delay was found in 38% and this was significantly more likely in girls (P = 0.03). Emotional and/or behavioural difficulties were reported in 85% of children. Internalising problem behaviours were more common than externalising problems. A diagnosis of an autism spectrum disorder was made in four children. In the six review assessments, regression was identified in three children.

Conclusions
Children who have experienced maltreatment and/or neglect may present with developmental delays and behavioural problems. Language delays and internalising problems are characteristic. There are many features in common with primary developmental disorders. The presence of fearfulness and hypervigilance may provide a clue to diagnosis.

Developmental and behavioural characteristics of children enrolled in a child protection pre-school.

This study aims to explore the relationship between developmental ability, autism and adaptive skills in preschoolers. Adaptive function was assessed in 152 preschoolers with autism, with and without developmental delay, and without autism, with and without developmental delay. Their overall adaptive function, measured by the general adaptive composite on the Adaptive Behaviour Assessment System, was closely correlated to developmental ability as measured by the general quotient on the Griffith Mental Development Scales. Children with autism performed significantly less well on both scales. Domain scores discriminated between children with and without autism, with poorer performance on both the social and practical domain scores for children with autism, even when controlling for the effects of development. Children with average development, both with and without autism, had lower adaptive skills than expected for their developmental level. The importance of considering domain scores as well as the general adaptive composite when determining support needs is emphasised.

Adaptive function in preschoolers in relation to developmental delay and diagnosis of autism spectrum disorders: Insights from a clinical sample

Aim
To study the socio-demographic and psychosocial risk factors of families presenting with their children for a diagnostic developmental assessment.

Methods
Socio-demographic details of children who had a multidisciplinary developmental assessment with the Child Assessment Team at Campbelltown Hospital between January 2009 and December 2010 were collated and compared with census data.

Results
In 2009 and 2010, 277 families were seen by the Child Assessment Team. A detailed socio-demographic profile was available for 251 (91%) families. Parents seen in the clinic were more likely to be younger, single, born overseas, have less post-school education, identify as Aboriginal and/or live in public housing compared with the district rates.

Conclusions
Families presenting to the developmental clinic have more socio-economic disadvantage compared with the referring district. This has implications for service delivery and clinical presentation, and highlights the importance of the social worker's role in a developmental diagnostic team.

Families referred to a Child Assessment Team: the Campbelltown experience.

Adaptive function is an essential dimension in the diagnosis of neurodevelopmental conditions in young children, assisting in determining the pattern of intellectual function and the amount and type of support required. Yet, little information is available on the accuracy of currently used adaptive function assessments for preschool children. This study compares the results of 2 commonly used assessments, the Adaptive Behavior Assessment System (ABAS-II) and the Vineland Adaptive Behavior Scales, Second Edition (Vineland-II), on a group of 52 preschoolers referred for investigation of delays in development. Standard scores on the Vineland-II were significantly higher than those on the ABAS-II, but both assessment scores could be used to identify patterns of adaptive functioning that would require support. The amount and type of support required could not be determined by standard scores on either assessment. Greater consistency between scales and grading the level of support required was achieved using age equivalent scores. Age equivalent scores on individual subscales showed motor and preacademic skills that were consistent with developmental level; performance on all other subscales was lower than developmental level. This study supports the use of standard scores to identify significant impairment in adaptive function and age equivalent quotient scores to describe the amount and area of support required.

Susan Milne

Papers

The Use of the Bayley Scales of Infant and Toddler Development III with Clinical Populations: A Preliminary Exploration

Developmental and behavioural characteristics of children enrolled in a child protection pre-school.

Adaptive function in preschoolers in relation to developmental delay and diagnosis of autism spectrum disorders: Insights from a clinical sample

Families referred to a Child Assessment Team: the Campbelltown experience.

Assessing Adaptive Functioning in Preschoolers Referred for Diagnosis of Developmental Disabilities.