Validation of a screening test based on symbols visual search to detect visuo-attentionnal reading difficulties

Visuo-attentional dyslexia has been associated with impaired simultaneous visual processing of multiple items made of separable features (i.e. symbols). We designed a visual search screening test, consisting to find the (unique) black circle among circles of various colours versus among circles combined with a bar of various length and location. We evaluated its reliability and its validity to detect visuo-attentional deficit prone to affect reading. RESULTS OF STUDY 1: Assessment of 2015 children between 3 and 11 years old established that the screening test was feasible from kindergarten, and that our index contrasting visual search performance for symbols relative to colours (the Temporal Gap) decreased with age. Satisfactory test-retest reliability of the standardised index (independent from age) was found on a sample of 69 individuals. RESULTS OF STUDY 2: Reading speed and inaccuracy assessed for 769 4th and 5th grades children were significantly correlated to the Temporal Gap. A Temporal Gap above 75th centile predicted reading efficiency deficit above 95th percentile with 63 % sensitivity and 71 % specificity.

Our screening test can be used in clinic to detect whether a child with developmental dyslexia presents visuo-attentional fragility prone to contribute to the reading difficulties. Its validity as early predictor of a risk to develop visuo-attentional dyslexia needs further investigation.