Positive and negative facial valence perception are modulated differently by eccentricity in the parafovea

Understanding whether people around us are in a good, bad or neutral mood can be critical to our behavior. Faces are optimally processed when directly looked at, but this is not always the case. While facial expressions of emotions are typically studied at central visual field, peripheral investigations mainly focus on locations to the right or left of fixation. Here we examined how perception of facial emotional valence (the pleasantness of the emotion) changes with distance from the center of the visual field (eccentricity). In blocked (n=51) and single-trial (n=37) experiments participants judged whether the valence of face images in the parafovea (<= 4 degrees) was positive (happy), negative (afraid), or neutral while their eyes were being tracked. We assumed that emotional valence perception would decrease with eccentricity and that different emotions may be influenced differently by eccentricity. On top of the expected performance reduction with eccentricity we found that positive valence perception was affected the least (10%-19% at 4 deg. and negative the most (35%-38% at 4 deg.) and this was consistent across both experiments and not a result of speed-accuracy trade-off or response biases (low-level visual acuity and high-level face memory were also controlled for). We also found that within-valence (but not across valence) performance was associated across eccentricities suggesting that perception of different valences is supported by different mechanisms. While our results may not generalize to all positive and negative emotions, they indicate that beyond-fovea investigations can reveal additional characteristics of the mechanisms that underlie facial expression processing and perception.