Theta-Band Neural Oscillations Reflect Cognitive Control During Language Processing.

As we interpret language moment by moment, we often encounter conflicting cues in the input that create incompatible representations of sentence meaning, which must be promptly resolved. Although ample evidence suggests that cognitive control aids in the resolution of such conflict, the methods commonly used to assess cognitive control's involvement in language comprehension provide limited information about the time course of its engagement. Here, we show that neural oscillatory activity in the theta-band (∼3–8 Hz), which is associated with cognitive control in nonlinguistic tasks like Stroop and Flanker, provides a real-time index of cognitive control during language processing. We conducted time-frequency analyses of four electroencephalogram data sets, and consistently observed that increased theta-band power was elicited by various kinds of linguistic conflict. Moreover, increases in the degree of conflict within a sentence produced greater increases in theta activity. These effects emerged as early as 300 ms from the onset of the initiating event, indicating rapid cognitive-control recruitment during sentence processing in response to conflicting representations. Crucially, the effect patterns could not be ascribed to processing difficulty that is not due to conflict (e.g., semantic implausibility was neither necessary nor sufficient to elicit theta activity). We suggest that neural oscillations in the theta-band offer a reliable way to test specific hypotheses about cognitive-control engagement during real-time language comprehension. Public Significance Statement: The results reported in this work provide the clearest evidence available that theta-band oscillations index cognitive control demands during language comprehension, thus extending previous findings that theta-band activity is elicited by representational conflict in cognitive tasks like Flanker and Stroop. Our findings support the growing body of work indicating that cognitive control plays a core role in ordinary language comprehension and provide a novel application of an established electrophysiological measure to study the real-time dynamics of cognitive control operations during sentence processing. The theta effects observed in this work, which appeared rapidly upon encountering the linguistic conflict, corroborate psycholinguistic models predicting that conflict during comprehension must be resolved quickly for successful communication. [ABSTRACT FROM AUTHOR]