Young children's difficulty in disregarding information from external features when matching unfamiliar faces.

Three experiments were conducted to examine developmental differences in reliance on internal (i.e., eyes, nose, mouth, and cheeks) or external (i.e., hairstyle) facial features between young children and adults when matching two unfamiliar faces. Participants viewed two facial images and were asked to decide whether the images showed the identical person or two different people. Four different types of stimuli were presented: two incongruent stimuli, in which the two images showed either the same internal face (i.e., same person) with different hairstyles or two different internal faces (i.e., different people) with the same hairstyle, and two congruent stimuli, in which the two images showed either the same face and hairstyle or two different faces and hairstyles. We found that children were more likely to base their responses on external hairstyles for the incongruent stimuli, unlike adults (Experiment 1), even when they were instructed to attend to internal features (Experiment 2). Eye movement data showed that both children and adults spent the most time gazing on the internal features and gave little attention to the external hairstyle, and children attended to each part of the internal features as long as, or even longer than, adults (Experiment 3). Children's response based on external hairstyles was due to their inability to disregard external information and was not attributed to their tendency to attend more frequently to external parts rather than internal parts.