Authors: Helland T, Tjus T, Hovden M, Ofte S, Heimann M
Title: Effects of Bottom-Up and Top-Down Intervention Principles in Emergent Literacy in Children at Risk of Developmental Dyslexia: A Longitudinal Study
Source: Journal of Learning Disabilities 2011 44(2): 105-122
Year: 2011
Research Design: Randomised Controlled Trial
Rating Score: 04/10
This rating is confirmed
Eligibility specified - Y
Random allocation - Y
Concealed allocation - N
Baseline comparability - N
Blind subjects - N
Blind therapists - N
Blind assessors - N
Adequate follow-up - Y
Intention-to-treat analysis - N
Between-group comparisons - Y
Point estimates and variability - Y

This longitudinal study focused on the effects of two different principles of intervention in children at risk of developing dyslexia from 5 to 8 years old. The children were selected on the basis of a background questionnaire given to parents and preschool teachers, with cognitive and functional magnetic resonance imaging results substantiating group differences in neuropsychological processes associated with phonology, orthography, and phoneme-grapheme correspondence (i.e., alphabetic principle). The two principles of intervention were bottom-up (BU), "from sound to meaning", and top-down (TD), "from meaning to sound." Thus, four subgroups were established: risk/BU, risk/TD, control/BU, and control/TD. Computer-based training took place for 2 months every spring, and cognitive assessments were performed each fall of the project period. Measures of preliteracy skills for reading and spelling were phonological awareness, working memory, verbal learning, and letter knowledge. Literacy skills were assessed by word reading and spelling. At project end the control group scored significantly above age norm, whereas the risk group scored within the norm. In the at-risk group, training based on the BU principle had the strongest effects on phonological awareness and working memory scores, whereas training based on the TD principle had the strongest effects on verbal learning, letter knowledge, and literacy scores. It was concluded that appropriate, specific, data-based intervention starting in preschool can mitigate literacy impairment and that interventions should contain BU training for preliteracy skills and TD training for literacy training.

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