Divided Visual Field Study of Depression, Cognition, and Mood

Abstract

This study compared the performance of 27 previously depressed and 21 never-depressed participants on a divided visual field task designed to examine the lateralization of emotional processing. Participants were asked to make judgments of emotional valence (positive or negative) for laterally presented words preceded by a centrally presented prime. Previous studies using this paradigm have found support for an enduring negativistic verbal processing bias in the right hemisphere among both depressed and previously depressed individuals. The present study represents an attempt to address several remaining questions regarding this phenomenon; specifically, this study aims to help clarify the respective roles of present mood state, anxious symptomatology, and prior depressive experience in giving rise to the aforementioned verbal processing bias. Participants in both diagnostic groups demonstrated an unusually large bias for words presented to the left hemisphere, such that their ability to accurately judge words presented to the right hemisphere was seriously compromised. Consequently, all participants who evidenced accuracy judgments for right hemisphere-presented words that were not significantly better than chance were excluded from further divided visual field analyses. The remaining 23 participants demonstrated a right visual field (left hemisphere) advantage for all words, and a valence-priming advantage for negative words. There were no significant differences between diagnostic groups, and no significant findings related to mood state for any of the divided visual field study variables, however, this was not unexpected given the limited power associated with this smaller sample of participants. A number of hypotheses to account for the poor accuracy rates on this task - particularly for the right hemisphere - are discussed. Additionally, there was some evidence to suggest that the sad mood state associated with the mood induction may not have endured for participants, and implications for future research are discussed.