Emotional distraction unbalances visual processing

Brain mechanisms used to control nonemotional aspects of cognition may be distinct from those regulating responses to emotional stimuli, with activity of the latter being detrimental to the former. Previous studies have shown that suppression of irrelevant emotional stimuli produces a largely right-lateralized pattern of frontal brain activation, thus predicting that emotional stimuli may invoke temporary, lateralized costs to performance on nonemotional cognitive tasks. To test this, we briefly (85 ms) presented a central, irrelevant, expressive (angry, happy, sad, or fearful) or neutral face 100 ms prior to a letter search task. The presentation of emotional versus neutral faces slowed subsequent search for targets appearing in the left, but not the right, hemifield, supporting the notion of a right-lateralized, emotional response mechanism that competes for control with nonemotional cognitive processes. Presentation of neutral, scrambled, or inverted neutral faces produced no such laterality effects on visual search response times.