You can find the original article here (open access).
In this study, we induced emotions towards pictures of other people in our participants with an economic trust game. Participants got to like one player, dislike another, and have neutral affect for the third (no interaction in the game). You may already know this design from our previous study.
After the game, we used the pics of the players’ faces as STOP signals in an inhibition task. We asked people to press a button as soon as they saw an arrow on the screen. Sometimes this arrow was followed by a face. In that case, participants were asked to stop themselves from pressing the button.
Importantly❗️, all faces had neutral expressions and the emotional load associated with the pictures was due to the social interactions in the game. We recorded participants’ brain activity in the whole task and we measured how accurate and fast they were in trials with and without the faces.
We expected that in trials with the liked and disliked faces, participants would be better in inhibiting their responses than in trials with the “neutral” faces. This was not the case. However, on the neural level we observed decreased brain responses (P3) in trials with the disliked faces.
This reduced P3 was surprising: it is often linked to enhanced cognitive control and we expected that the emotion-loaded stop signals would increase the P3’s amplitudes. There are many examples in the literature which show larger P3 in emotional conditions of inhibitory tasks.
However, it has been previously shown that untrustworthy persons elicit smaller P3 than trustworthy ones. The disliked persons in our study played unfairly in the game, so they could indeed be considered untrustworthy. This would explain the smaller P3 we found in response to their faces.
Since the social and affective knowledge of the faces acquired in the game might have played a big role in our cognitive (inhibitory) task, we explored it further. For that, we looked into the sources of the P3 amplitudes in the brain (with a source-localisation analysis).
We found a stronger activation in brain structures involved in theory-of-mind and social judgement, which let us make inferences about others’ mental states. So, it looks like when seeing the disliked persons, participants activated their “what are they thinking” and “are they trustworthy” areas.
To sum up:
- Emotional valence was induced via social interactions (naturalistic exchange game)
- (Neutral) faces of disliked persons elicited mentalising rather than basic emotional responses
- These processes interacted with cognitive processing (inhibition)