Predicting children's word-spelling difficulty for common English words from measures of orthographic transparency,...

Spencer demonstrated that spelling and reading difficulty for English words can be predicted from a number of factors, including word frequency, phonemic length and measures of orthographic depth and complexity. In this study, spelling difficulty of high frequency words was investigated across five year groups (ages 7 to 11 years) with a wide ranging series of data sources from which to determine word frequency values and orthographic depth measures. A regression model accounted for 52-66% of the variance for 7- to 11-year-olds and 72% of the variance for the lowest performing quartile group, irrespective of age. The most influential factor, phonetic difference (being the difference in the number of letters and phonemes in a word, and representing grapheme complexity), links the relative influence of large graphemic units in foundation literacy to a similar phenomenon, the 'whammy' effect, which provides support for serial processing in the dual route cascade model of word recognition in skilled readers (Rastle & Coltheart, 1998). The study supports recent research on European orthographies, which concludes that both orthographic depth and complexity contribute to delayed acquisition of foundation literacy skills.