Asymmetry in alpha power predicts accuracy of hemispheric lexical decision

Objective: Previous work has shown that individual differences in resting alpha asymmetry are associated with efficacy on a variety of cognitive tasks. Still unresolved is how ongoing alpha asymmetry relates to behavioral asymmetry, explored here using lateralized lexical decision. Methods: Alpha power immediately preceding lexical decision trials was measured to assess cognitive engagement during word recognition. This was compared with behavioral performance for the task, measured by accuracy and latency of the lexical decision response. Results: Greater relative left hemisphere alpha power (i.e. higher asymmetry) immediately before presentation of a word led to reduced likelihood for its successful identification. Greater alpha asymmetry was also associated with reduced performance for identifying stimuli lateralized to the right visual field. Conclusions: Word recognition is facilitated by decreased asymmetry in cognitive engagement in the two cerebral hemispheres, particularly when the stimuli are lateralized to the left hemisphere (right visual field). Significance: Results address the role of cognitive engagement in the two cerebral hemispheres, and its relationship with lexical access.