Research Projects Funded by IDA 

Summary: 

The Influence of Morphological Structure on the Word Reading of Children with and without Reading Disabilities

(The Effects of Phonological Complexity on Students? Reading of Morphologically Complex Words) A particular challenge for students with reading difficulties in the middle school and junior high years is learning to read derived words both accurately and fluently. Previous studies have shown that students are better at reading, stable, derived words, in which the sound and spelling of the base morpheme are preserved in the derived form (e.g., cultural), than they are at reading “shift” words, in which the base form has a different sound and/or spelling in the derived counterpart (e.g., natural). Poor readers, who tend to have phonological processing problems might be expected to have particularly serious difficulties reading shift words relative to average readers. One reason might be that preliminary aspects of accessing the complex phonological relations of shift words interfere with rapid word recognition. We explored this possibility with a lexical decision task, which does not require pronunciation of the word aloud. An interaction of task (naming versus lexical decision) and word type (shift versus stable) for poor readers but not average readers would suggest a specific problem accessing and/or organizing complex phonological relations for poor readers. Our goal, then, was to compare naming and recognition of complex words (shift and stable, matched for spelling and frequency) by poor and average readers. The subjects were 18 poor readers, with standardized word reading scores below 90 and 33 average readers, whose score on this measure was above 90. All students (ages 10 - 15) attended one of two schools for students with learning disabilities; they had receptive vocabulary in at least the low average range. The students performed three tasks on a computer. One was a word naming task, for which students pronounced aloud the word that appeared on the screen. The second was a lexical decision task, for which the students indicated by pressing a button whether or not the letter string on the screen was a word. The third was a simple, two-choice naming task that involved saying “plus” or “star” when the symbol (+++ or ***) appeared on the screen. For all three tasks, accuracy and response latencies were recorded. The results showed that on the word naming task, both poor and average readers were less accurate and slower on shift than stable words, although the effect was significantly greater for the poor readers. In contrast, on the lexical decision task, where pronunciation was not required, recognition of shift and stable words did not differ significantly for either poor or average readers. Although poor readers, in particular, tended to be slower at responding to shift than stable words, the effect was not significant. For poor readers, but not average readers, a significant interaction of task and transparency of morphological structure showed particular problems with shift words when the phonological representation had to be processed fully for purposes of pronunciation. Further statistical analyses indicated that the above findings were not the result of group differences in general processing speed or receptive vocabulary. One educational implication of these findings is that poor readers need explicit practice with the systematic phonological changes that are likely to occur when suffixes are added to words (e.g., stress changes and vowel shortening).