Bipolar disorder (BD), along with schizophrenia, is one of the most severe psychiatric conditions and is correlated with attentional deficits and emotion dysregulation. Bipolar patients appear to be highly sensitive to the presence of emotional distractors. Yet, no study has investigated whether perceptual load modulates the interference of emotionally distracting information. Our main goal was to test whether bipolar patients are more sensitive to task-irrelevant emotional stimulus, even when the task demands a high amount of attentional resources.

Fourteen participants with BD I or BD II and 14 controls, age- and gender-matched, performed a target-letter discrimination task with emotional task-irrelevant stimulus (angry, happy and neutral facial expressions). Target-letters were presented among five distractor-letters, which could be the same (low perceptual load) or different (high perceptual load). Participants should discriminate the target-letter and ignore the facial expression. Response time and accuracy rate were analyzed.

showed a greater interference of facial stimuli at high load than low load, confirming the effectiveness of perceptual load manipulation. More importantly, patients tarried significantly longer at high load. This is consistent with deficits in control of attention, showing that bipolar patients are more prone to distraction by task-irrelevant stimulus only when the task is more demanding. Moreover, for bipolar patients neutral and angry faces resulted in a higher interference with the task (longer response time), compared to controls, suggesting an attentional bias for neutral and threating social cues. Nevertheless, a more detailed investigation regarding the attentional impairments in social context in BD is needed.