Figure 1. Schematics depiction of an example trial with incongruent facial expression.

The suppressed face image was presented to one eye with its contrast gradually ramped up, and was expected to be suppressed by the dynamic noise. The contrast of the suppressed face image was ramped up linearly from 0 to 40% of its original contrast within a period of 600 ms from the beginning of the trial and then remained constant until the participant had made a response. When the suppressed face reached a stable contrast, the target face image (happy or fearful) was presented on the other side of the fixation cross to both eyes, thus visibly for 200 ms before it disappeared. Participants were asked to respond, as quickly as possible, to the target face image, by pressing one of two keys to indicate whether it was happy or fearful.