Effects of induced moods on semantic memory activation in single-word imagery processing

The effect of affective state or mood on language processing has been examined in behavioral and event-related potential (ERP) studies. Although these studies have shown that mood affects the process of context integration of a sentence, it remains unclear whether mood influences processing of single-word imagery. This study examined the effects of word imageability on the N400 and N700 components of the ERP in a reaction time (RT) task, in which 30 university students judged whether or not a word easily evoked visual imagery. Three mood conditions were induced by autobiographical recollection and pictures of facial expressions (neutral, positive, and negative) and conducted in a counterbalanced order. High imagery words produced faster judgments and larger amplitudes of N400 and N700 components than did low imagery words. Although mood did not affect RT or N700 amplitude, N400 amplitude was larger (more negative-going) under positive mood than under negative mood, with neutral mood intermediate, regardless of word imageability. The interaction effect of mood and word imageability was not significant. These results suggest that, compared to negative mood, positive mood facilitates activation of semantic memory and access to lexical representations when imagery processing is required.