Sublexical orthographic knowledge's predictive power for spelling accuracy in skilled adult readers

Literacy skills such as reading and spelling are not only crucial for participating in today's society, but they are also a human right. Efficient spelling occurs through the coordination of many subskills, including sublexical orthographic knowledge. Sublexical orthographic knowledge is the understanding of the letter regularities of a given language. This study addresses the gap found with adult spellers by evaluating whether sublexical orthographic knowledge is related to spelling accuracy in adults. I hypothesize that sublexical orthographic knowledge will contribute unique variance to spelling accuracy in adult readers. Further, I predict a greater relation between sublexical orthographic knowledge and accuracy in spelling regular words vs. irregular words. Participants took a spelling test of regular words that followed the typical English sound-letter mappings and irregular words that do not follow these patterns. I created a novel letter detection task to measure sublexical orthographic knowledge. A repeated measures ANOVA indicated that there is no significant effect of letter string frequency or placement of the target in the letter string, indicating that there is currently no evidence that the letter detection task measures sublexical orthographic knowledge. Despite this, a hierarchical regression found that the results of the letter detection task account for unique variance in spelling accuracy in adult readers. More research is needed to see if the letter detection task in fact measures sublexical orthographic knowledge, and if not, what letter detection skill is it measuring.