Electroencephalography delta, theta, and alpha oscillations in valence-space metaphorical associations.

Conceptual metaphor theory holds that understanding abstract affective words relies on concrete spatial information, known as valence-space metaphorical associations. Previous studies show that these metaphorical associations are related to several event-related potentials. However, we know nothing about the neural oscillations underlying these associations. The present study adopted a priming paradigm and the electroencephalographic time-frequency analysis to reveal the brain oscillatory activities related to the processing of valence-space associations. In the experiment, participants first memorized a positive or a negative word. Then, a dot was presented at the higher or lower position of the screen and was horizontally centered. Participants detected the location of the cue and made behavioral responses while their brain electrical activities were recorded. Results found that (a) when participants memorized a negative word and judged the lower spatial cue, the power of the delta band was suppressed compared with memorizing a positive word; (b) when participants memorized a positive word and judged the higher spatial cue, the power of the theta band was suppressed compared with memorizing a negative word; (c) when participants memorized a negative word and judged the lower spatial cue, the power of the alpha band was suppressed compared with memorizing a positive word. These event-related desynchronization results suggest that the processing of valence-space associations is related to inhibition, attention, working memory, and semantic process. The present study provides the first evidence of cortical oscillations involved in conceptual metaphors.