Dyslexia
Conditions
Brief summary
Developmental dyslexia is a common and serious specific learning disability affecting up to one in eight children in Hong Kong, with profound consequences for academic success and personal well-being. For children learning to read the visually complex Chinese script, the challenge is particularly intense. A key research challenge is a long-standing "chicken-and-egg" debate: are weaknesses in the brain's fast-processing visual system (Magnocellular-Dorsal deficits) a cause of reading difficulties, or merely a consequence of limited reading practice? This uncertainty has constrained theoretical progress, creating a major barrier to developing effective, evidence-based support for struggling readers beyond traditional linguistic-based methods. This project is designed to resolve this debate by directly testing if training a core visual-attentional skill can causally improve reading. The approach is built on investigator's strong pilot data, which established a novel "Neurocognitive Cascade Model": a framework suggesting that the integrity of foundational visual processing impacts reading through a sequential chain reaction flowing from visual attention to working memory. To test the model, investigators will employ a rigorous, assessor-blind randomized controlled trial with 100 Cantonese-speaking children with developmental dyslexia. Participants will be randomly assigned to either an intervention group that plays action video games, scientifically proven to enhance visual attention, or an active control group that plays a different type of non-action, engaging game. This design allows investigators to isolate the specific impact of the visual-attentional training. The investigators will track changes at four time points-before, during, immediately after the intervention, and at a 6-month follow-up-using a multi-level assessment battery, including objective neural signals of visual processing, cognitive skills, and real-world reading performance measured with advanced eye-tracking technology. This research will deliver new knowledge that is both scientifically and socially impactful. It will provide the first causal evidence for a visual-attentional pathway to reading remediation in Chinese developmental dyslexia, fundamentally shifting theoretical understanding of the disorder from a single, phonological deficit to a more comprehensive, multi-component model. The findings will have a significant translational impact, paving the way for innovative, non-reading-based interventions and new early screening tools. Ultimately, this project will offer a new, evidence-based approach to help children overcome the specific neurocognitive bottlenecks that hinder their ability to learn to read, with the potential to improve educational outcomes for a large and underserved population.
Interventions
BEHAVIORALAction video game intervention group
Participants will undergo 12 hours of training with a commercially available AVG (Rabbids: Party of Legends). This game is a direct successor to the Rayman Raving Rabbids game used in AVG intervention studies and shares its core mechanics. The game consists of numerous fast-paced mini-games in which players track multiple objects, respond to unpredictable events, and filter out distractions, thereby placing high demands on visual-spatial attention and attentional control.
BEHAVIORALActive Control (Non-Action Video Game) Group
Participants will undergo 12 hours of training with SimCity. To control for non-specific effects (e.g., gaming time, engagement, motivation), this group will play a non-action video game of matched duration and format. The investigators will use a commercially available city-building and management simulation game (e.g., SimCity), which is engaging and cognitively demanding (requiring planning and resource management). However, it critically lacks the fast, unpredictable, and attention-intensive elements of action games, ensuring that any observed group differences can be attributed specifically to the visual-attentional training provided by the AVG.
Sponsors
The Hong Kong Polytechnic University
Study design
Allocation
RANDOMIZED
Intervention model
FACTORIAL
Primary purpose
HEALTH_SERVICES_RESEARCH
Masking
TRIPLE (Caregiver, Investigator, Outcomes Assessor)
Masking description
Upon providing informed consent from both caregivers and children, eligible children will complete the comprehensive Pre-Intervention (T1) assessment battery. The participants will then be assigned to either the Intervention or the Active Control group using stratified blocked randomisation. Participants will be stratified based on baseline reading severity (high vs. low) and comorbid Attention-Deficit/Hyperactivity Disorder (ADHD) symptoms (high vs. low). Within each stratum, a computer-generated algorithm will randomise participants in blocks of six to ensure a balanced allocation across conditions. All research staff conducting the assessments will be blinded to the group allocation.
Intervention model description
The primary objective of this project will be to provide the first causal validation of our novel Neurocognitive Cascade Model. To achieve this, the investigators will use Action Video Game (AVG) training as a targeted, non-linguistic intervention. This approach will strategically address several critical gaps in the literature. Although AVG training has shown potential for improving reading in children with dyslexia (DD), its efficacy remains debated, with a study failing to replicate positive findings. Furthermore, two crucial issues remain unresolved: (1) as the vast majority of research has focused on alphabetic languages, the effectiveness of AVG training for logographic scripts such as Chinese remains unknown, and (2) the neurocognitive mechanisms underlying any transfer of skills to reading remain poorly understood.
Eligibility
Sex/Gender
ALL
Age
7 Years to 10 Years
Healthy volunteers
No
Inclusion criteria
* Formal diagnosis of dyslexia by an educational or clinical psychologist using the Hong Kong Test of Specific Learning Difficulties in Reading and Writing (HKT-SpLD),39 with a literacy composite score at or below the 10th percentile. * Non-verbal IQ score ≥ 85 on Raven's Standard Progressive Matrices. * Normal or corrected-to-normal vision (both eyes logMAR 0.1 or better).
Exclusion criteria
History of neurological or psychiatric disorders (e.g., epilepsy, psychosis).
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Visual Attention Span | Baseline measurement on day 1, Mid-Intervention on day 1, within 30 minutes post-Intervention on day 1, and Follow-Up on day 180 | Cued Number Identification Task: This task assesses the rapid deployment of visual attention. A string of five numbers (Geneva font, size 24, 98% contrast) is presented for 200 ms, followed by a 50-ms visual cue 1 cm beneath the target number. Numbers are spaced to subtend a 3.8° visual angle and minimise lateral masking. The child's task is to verbally report the cued number. The primary metric is the number of correctly reported targets out of 20 trials. |
Countries
Hong Kong
Contacts
CONTACTTsz Wing Leung, PhD
Outcome results
None listed