N320 Latency

A Stimulus Category by Hemisphere ANOVA was performed on the N320 peak latency measured at T3 and T4 (where the amplitude of the N320 elicited by pronounceable stimuli was maximal). This analysis showed that N320 latency was significantly shorter for nonpronounceable stimuli (303 msec) than for pronounceable stimuli (326 msec) (F(1, 23) = 16.55, p < 0.001), without a significant main effect of hemisphere ((F(1, 23) < 1.00).

The interaction between Stimulus Category and Hemisphere, however, was significant (F(1, 23) = 5.68, p <0.025), revealing that in response to pronounceable stimuli the N320 peaked earlier at T3 (321 msec) than at T4 (331 msec), whereas in response to nonpronounceable stimuli it peaked earlier at T4 (297 msec) than at T3 (309 msec). Hence, the left hemisphere responded faster to pronounceable than to nonpronounceable stimuli, whereas the opposite pattern was found for the right hemisphere.

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Figure 4. ERPs elicited bynontarget stimuli (words,pseudowords, and nonwords)at the sites in the lexical deci-sion task. The N350 wave waslargest at T3—on the left tem-poral hemisphere—and waselicited only by words andpseudowords. Unlike legalphonological stimuli, non-words elicited a large positivedeflection.