Spanish is a transparent language with a high degree of consistency of print-speech correspondences, thus facilitating written word recognition. However, most of the orthographic errors in Spanish do not alter the phonological representation of the words, thus leading to potential conflicts with their visual portrayal in memory. This study explored whether spelling errors affect semantic processing by analyzing the behavioral and electrophysiological effects during sentence reading in 35 native Spanish-speaking young adults. The experimental paradigm consisted of 170 six-word sentences
the closing word of each sentence could be a) congruent, b) congruent with a homophone error, c) congruent with a typo error, d) incongruent, and e) incongruent with a homophone error. Participants performed a semantic decision task with simultaneous EEG recording, in which they were explicitly instructed to ignore spelling errors and to attend only to the semantic congruency of the sentence when responding. Behaviorally, accuracy only decreased with typo errors, while mean reaction times were significantly increased by both types of errors. Electrophysiological results showed a classic N400, in which orthographic errors had no effect, reinforcing the notion that this component is mainly determined by semantic incongruency. On the other hand, orthographic expectancy violations were reflected by a late slow positivity rather than a larger N400 amplitude suggesting that spelling information is not fully processed when deeper, more complex linguistic aspects of written language are being analyzed. This P600-like component is interpreted as signaling the re-evaluation of an error, regardless of whether it is semantic or orthographic in nature.