Valence based emotions altered by emotion judgement task: Observer or Expresser effect

Behavioural studies have reported hemifacial bias suggesting one-half of the face to be more expressive. In our previous study, we provided neurological evidence (using MEG) for hemi-facial bias. Previous literature provides evidence that emotion recognition is affected by the judgement task (Observer or Expresser), but how hemi-facial bias interacts with emotion judgement task has gained very little attention. Here, we present results from two MEG studies. In the first study, the participants (N=13) were presented with both positive (+90 & +45 degree) and negative (-90 & -45 degree) faces depicting Happy and Sad emotions for 1000 ms and they had to report the emotion depicted in the stimuli. In the second study, the participants (N=24) were presented with rapid stimulation of emotional faces for 500 ms followed by two other pictures. They were asked to match it with the target face (emotion). To increase the complexity of judgement, the target picture was changed while keeping emotion constant. The data for both the studies was collected at the Northern Ireland Functional Brain Mapping (NIFBM) facility available at Ulster University, UK. We report a strong effect of hemi-facial effect in first study (Observer). The differential amplitude of evoked responses activity from happy and sad emotion emerged only in positive face angles, but not for negative face angles. This effect was not found for expressers (second study). The findings support the behavioral literature focusing on role of judgement task on emotion recognition.