N400 Event-Related Potential and Standardized Measures of Reading in Late Elementary School Children: Correlated or Independent?

We investigated whether and how standardized behavioral measures of reading and electrophysiological measures of reading were related in 72 typically developing, late elementary school children. Behavioral measures included standardized tests of spelling, phonological processing, vocabulary, comprehension, naming speed, and memory. Electrophysiological measures were composed of the amplitude of the N400 component of the event-related potential waveform elicited by real words, pseudowords, nonpronounceable letter strings, and strings of letter-like symbols (false fonts). The only significant brain-behavior correlations were between standard scores on the vocabulary test and N400 mean amplitude to real words (r = -.272) and pseudowords (r = -.235). We conclude that, while these specific sets of standardized behavioral and electrophysiological measures both provide an index of reading, for the most part, they are independent and draw upon different underlying processing resources. [T]o completely analyze what we do when we read… would be to describe very many of the most intricate workings of the human mind, as well as to unravel the tangled story of the most remarkable specific performance that civilization has learned in all its history(Huey, 1908/1968, p. 3).