Developmental Changes in Gaze Behavior and the Effects of Auditory Emotion Word Priming in Emotional Face Categorization.

Social interactions often require the simultaneous processing of emotions from facial expressions and speech. However, the development of the gaze behavior used for emotion recognition, and the effects of speech perception on the visual encoding of facial expressions is less understood. We therefore conducted a word-primed face categorization experiment, where participants from multiple age groups (six-year-olds, 12-year-olds, and adults) categorized target facial expressions as positive or negative after priming with valence-congruent or -incongruent auditory emotion words, or no words at all. We recorded our participants' gaze behavior during this task using an eye-tracker, and analyzed the data with respect to the fixation time toward the eyes and mouth regions of faces, as well as the time until participants made the first fixation within those regions (time to first fixation, TTFF). We found that the six-year-olds showed significantly higher accuracy in categorizing congruently primed faces compared to the other conditions. The six-year-olds also showed faster response times, shorter total fixation durations, and faster TTFF measures in all primed trials, regardless of congruency, as compared to unprimed trials. We also found that while adults looked first, and longer, at the eyes as compared to the mouth regions of target faces, children did not exhibit this gaze behavior. Our results thus indicate that young children are more sensitive than adults or older children to auditory emotion word primes during the perception of emotional faces, and that the distribution of gaze across the regions of the face changes significantly from childhood to adulthood.