In a three-year longitudinal study 471 children were classified, based on their performances on arithmetic tests in first and second grade, as having persistent arithmetic disabilities (AD), persistent low achieving (LA), persistent typical achieving, inconsistent arithmetic disabilities (DF1) or inconsistent low achieving in arithmetic. Significant differences in the performances on the magnitude comparison in kindergarten (at age 5 to 6) were found between the AD and LA and between the AD and DF1 groups. Evidence from a three year longitudinal study on the role of preparatory arithmetic abilities

Background: Delay aversion, the motivation to escape or avoid delay, results in preference for small immediate over large delayed rewards. Delay aversion has been proposed as one distinctive psychological process that may underlie the behavioural symptoms and cognitive deficits of attention deficit/ hyperactivity disorder (ADHD). Furthermore, the delay aversion hypothesis predicts that ADHD children's preference for immediate small over large delayed rewards will be reduced when stimulation, which makes time appear to pass more quickly, is added to the delay interval. The current paper tests these predictions. Methods: A group of children with a diagnosis of ADHD (with or without oppositional defiant disorder (ODD)), a group with a diagnosis of high-functioning autism (HFA), and a normal control group were compared on an experimental paradigm giving repeated choices between small immediate and large delayed rewards (Maudsley Index of Delay Aversion-MIDA) under two conditions (stimulation and no stimulation). Results: As predicted, ADHD children displayed a stronger preference than the HFA and control children for the small immediate rewards under the no-stimulation condition. The ADHD children preferences were normalised under the stimulation condition with no differences between the groups. This pattern of results was the same whether the ADHD children had comorbid ODD or not. Discussion: The findings from the MIDA are consistent with the delay aversion hypothesis of ADHD in showing that preference for small immediate rewards over large delayed rewards is a specific feature of ADHD and that this preference can be reduced by the addition of stimulation. Further research is required to better understand the emotional and motivational mechanisms underpinning delay aversion.

Previous research stresses the importance of seriation, classification, and counting abilities that should be assessed in kindergarten, when looking for crucial predictors of mathematical learning disabilities in Grade 1. This study examines ( n = 158) two-year-long predictive relationships between children's seriation, classification, procedural counting knowledge, and conceptual counting knowledge, and their numerical facility and arithmetical achievement in Grades 3, 4, and 5. Path analyses reveal a relationship between procedural counting knowledge in Grades l and 3 and numerical facility, and between conceptual counting knowledge in Grade l and arithmetical achievement in Grades 1 and 2. In addition, procedural counting knowledge correlates with seriation, and conceptual counting knowledge correlates with classification as well as with seriation in Grade 1. Clinicians are encouraged to select early arithmetic subtests with caution when assessing and predicting arithmetic and arithmetical disabilities.

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Procedural and conceptual counting knowledge, seriation and classification skills and magnitude comparison abilities could possibly serve as powerful early screeners in the detection of mathematical disabilities.