Many discussions about the existence of cognitive and affective bias in anxiety or depressive disorders can be found in current literature.
For instance, an affective bias can impair emotional expression decoding, but actually, we don’t know if this bias would belong to the negative cognitive set described by Beck, suggesting an attraction for negative stimuli, or if it would correspond to an absence of attraction for positive stimuli. Moreover, research failed to determine the attentionnal or decisional locus of this kind of bias.
To answer this questions, emotional oddball paradigm was analyzed in 32-channels averaged event-related potentials (ERPs) recorded from twelve subjects with depressive tendencies and paired subjects while seeing frequent stimuli as neutral emotional face and having to detect as quickly as possible rare stimuli with happy or sad expression. Signifiant effects of emotional content were found on the attentional N200 component in subjects with depressive tendencies, as evidenced by a delayed N200 peak for rare sad as compared with rare happy stimuli. On P300, subjects with depressive tendencies showed longer latency onset as compared with normal controls.
These results can be interpreted as a "negative attentional bias" towards sad stimuli. The same design was also applied to anxious people, and significant differences on attentional N200 component were also described.
We suggest that ERPs could give us the opportunity to define the exact locus of action (attentional or decisional) of the emotional deficits observed in many psychiatric populations.