Purpose: This study investigated the effects of lexical access speed and letter access speed on reading fluency and reading comprehension. We hypothesized that 1) letter access speed would correlate with reading fluency but not comprehension, while 2) lexical access speed would influence reading comprehension. For readers who are struggling with recoding, most of the reading effort is probably tied up with recoding, leaving little to be explained by lexical access. Therefore we expected that 3) lexical access speed would primarily predict reading fluency for readers who were no longer struggling with recoding.
Method: 85 Grade 5 students completed tasks of reading accuracy, fluency, and comprehension. In addition they were tested on isolated letter naming and isolated picture naming tasks as measures of letter and lexical access speed. All items in both naming tasks were unique. Parallel serial rapid automatized naming measures with letters and objects were also taken.
Results: In the full sample letter access speed, but not lexical access speed, accounted for unique variance in reading fluency. The reverse was true for reading comprehension. Half the sample were at-ceiling recoders (95% accuracy). In this subset sample, both letter access and lexical access accounted for unique variance in reading fluency. The pattern of effects for lexical access did not change by controlling for serial rapid naming (RAN).
Conclusions: The results suggest that letter access and lexical access are important for different aspects of reading. In addition, the influence of lexical access on reading appears to change with reading development.