Reading words with irregular decoding rules: a test of premorbid cognitive function?
The present study investigated the relation between level of general cognitive function and the oral reading of irregular words in Swedish. Swedish is an orthographically regular language, so many irregular words are loan words from other languages. A test comprising such words (irregularly spelled words (ISW)) was designed, and tested on a sample of 48 healthy Swedish adults, stratified according to age, gender, and level of education. The results confirmed that the ability to read words that do not follow the regular rules for decoding in Swedish was positively related to general cognitive level. ISW in combination with demographic variables gave a good estimate of general cognitive function and a better estimate than demographic variables alone. Exposure to written and spoken vocabulary during the lifespan may be indexed by ISW performance, for factor analysis suggested that this may constitute a discrete factor contributing to cognitive function.