Effects of Grammaticality and Morphological Complexity on the P600 Event-Related Potential Component

<div><p>We investigated interactions between morphological complexity and grammaticality on electrophysiological markers of grammatical processing during reading. Our goal was to determine whether morphological complexity and stimulus grammaticality have independent or additive effects on the P600 event-related potential component. Participants read sentences that were either well-formed or grammatically ill-formed, in which the critical word was either morphologically simple or complex. Results revealed no effects of complexity for well-formed stimuli, but the P600 amplitude was significantly larger for morphologically complex ungrammatical stimuli than for morphologically simple ungrammatical stimuli. These findings suggest that some previous work may have inadequately characterized factors related to reanalysis during morphosyntactic processing. Our results show that morphological complexity by itself does not elicit P600 effects. However, in ungrammatical circumstances, overt morphology provides a more robust and reliable cue to morphosyntactic relationships than null affixation.</p></div

Interaction between grammaticality and morphological complexity.

<p>Grand mean ERP waveforms for all four sentence conditions over central parietal and occipital electrodes: grammatical, morphologically simple (black dashed line), grammatical, morphologically complex (black solid line), ungrammatical, morphologically simple (red dashed line), and ungrammatical, morphologically complex (red solid line). Onset of the critical word in the sentence is indicated by the vertical bar. Calibration bar shows 3μVof activity; each tick mark represents 100ms of time. Negative voltage is plotted up.</p

Example experimental stimuli.

<p>Note: The critical word for ERP averaging is underlined.</p><p>Example experimental stimuli.</p

ERP responses to morphologically complex stimuli.

<p>Grand mean ERP waveforms for sentences with morphologically complex, grammatical critical words (black line) and sentences with morphologically complex, ungrammatical critical words (red line). Onset of the critical word in the sentence is indicated by the vertical bar. Calibration bar shows 3μVof activity; each tick mark represents 100ms of time. Negative voltage is plotted up.</p

End-of-sentence judgment task accuracy.

<p>Note: SE = standard error</p><p>End-of-sentence judgment task accuracy.</p

ERP responses to morphologically simple stimuli.

<p>Grand mean ERP waveforms for morphologically simple, grammatical critical words (black line) and sentences with morphologically simple, ungrammatical critical words (red line). Onset of the critical word in the sentence is indicated by the vertical bar. Calibration bar shows 3μVof activity; each tick mark represents 100ms of time. Negative voltage is plotted up.</p