Self-face perception in 12-month-old infants: A study using the morphing technique

The present study investigated self-face perception in 12-month-old infants using the morphing technique. Twenty-four 12-month-old infants participated in both the main and control experiments. In the main experiment, we used the participant's own face, an unfamiliar infant's face (age- and gender-matched), and a morphed face comprising 50 % each of the self and unfamiliar faces as stimuli. The control experiment followed the same procedure, except that the self-face was replaced with another unfamiliar face. In both experiments, two of these stimuli were presented side by side on a monitor in each trial, and infants' fixation duration was measured. Results showed that shorter fixation durations were found for the morphed face compared with the self-face and the unfamiliar face in the main experiment, but there were no significant preferences for any comparisons in the control experiment. The results suggest that 12-month-old infants could detect subtle differences in facial features between the self-face and the other faces, and infants might show less preference for the self-resembling morphed face due to increased processing costs, which can be interpreted using the uncanny valley hypothesis. Overall, representations of the self-face seem to a certain extent to be formed by the end of the first year of life through daily visual experience.