| This study undertakes to answer the following question: what are the signal properties of the brain related to the conscious and unconscious processing of subjective affective stimuli? We hypothesized that (1) subjective ratings of emotionally valent stimuli can be differentiated by event-related potentials (ERPs), and (2) subliminal and supraliminal stimuli can be differentiated by ERPs. ERP component amplitude measures (N100, P200, P300, and N400) were used to relate subjective ratings of emotional stimuli (Osgood semantic differential evaluative scale) with both supraliminal (conscious) and subliminal (unconscious) presentations of these emotional stimuli. Four datasets were used to investigate these hypotheses. Two datasets use words as stimuli and two datasets use schematic faces as stimuli. A consistent set of analyses was applied across these four data sets looking at pleasant and unpleasant emotion ratings and conscious and unconscious processing. Findings supported both hypotheses. Component amplitudes differentiated pleasant from unpleasant stimuli, both supraliminally and subliminally. For words a positivity across component for negative words supraliminally was found. For one of two datasets based on words this pattern reversed subliminally, the other showed a pattern consistent with the supraliminal. For faces, an interrelationship among components differentiated the pleasant and unpleasant stimuli both supraliminally and subliminally. However, this differentiation for faces showed exactly opposite component amplitude directions supraliminally and subliminally. Findings are discussed in the context of growing interest in basic research in the areas of emotion and unconscious processing. |
