The right hemisphere's contribution to emotional word processing in currently depressed, remitted depressed, and never-depressed individuals

To examine how unipolar depression influences hemispheric processing of emotional stimuli, words with clear affective content were assessed by depressed, remitted depressed, and never depressed participants. Semantic stimuli were selected for both their valence (positive vs. negative) and for their ability to engender affective arousal (high vs. low). After completing a structured clinical interview to determine depression experience, participants were asked to make valence judgements for laterally presented emotional words. Study results suggest that the right hemisphere (RH) is particularly sensitive to the affective semantic content of emotional stimuli, furthermore, two interesting higher order interactions were observed in the RH. First, in a replication of recent findings by Atchley et al. [2003. Hemispheric asymmetry in the processing of emotional content in word meanings: The effect of current and past depression. Brain and Language, 84, 105–119], individuals who have experienced depression (both currently depressed and remitted depressed groups) show an advantage when processing negatively valent words, while the never depressed individuals show an advantage for positive words. Also in the RH, affective arousal interacted with stimulus valence (but not diagnostic group), such that all participants exhibited an advantage when categorizing highly arousing negative information, while for positive words the low arousing stimuli were identified more accurately. These results are discussed in the context of models of depressive cognition and in regards to general models of hemispheric specialization for emotion processing.