The left perceptual bias for adult and infant faces in adults and 5-year-old children: Face age matters

Abstract

A large number of studies have shown that adults rely more heavily on information conveyed by the left side of the face in judging emotional state, gender and identity. This phenomenon, called left perceptual bias (LPB), suggests a right hemisphere lateralization of face processing mechanisms. Although specialization of neural mechanisms for processing over-experienced face categories begins during the first year of life, little is known about the developmental trajectory of the LPB and whether or when the bias becomes selective for specific face categories as a result of experience. To address these questions we tested adults (Experiment 1) and 5-year-old children (Experiment 2) with null or limited experience with infants in an identity matching-to-sample task with chimeric adult and infant faces, for which both adults and children have been shown to manifest differential processing abilities. Results showed that 5-year-olds manifest a leftward bias selective for adult faces, and the magnitude of the bias is larger for adult compared to infant faces in adults. This evidence is in line with earlier demonstrations of a perceptual processing advantage for adult faces in adults and children and points to the role of experience in shaping neurocognitive specialization for face processing.

Keywords:

• Left perceptual bias
• Face age
• Children
• Adults
• Chimeric faces

The authors are indebted to the children who donated their time to participate in the study and the staff at the day care centres “Scuola dell'Infanzia San Cirillo”, in Busto Arsizio (VA) and “Scuola dell'Infanzia di Antegnate”, in Antegnate (BG), where the children were tested for their collaboration. The authors thank Melissa Martinelli for her help in testing children and adults and Lucia Gava for helping in creating stimuli and programming the task.

This research was funded by a grant from the University of Milano-Bicocca to the last author and a scholarship from the same University to the first author.

For the last author, Macchi Cassia is the double family name.

The authors are indebted to the children who donated their time to participate in the study and the staff at the day care centres “Scuola dell'Infanzia San Cirillo”, in Busto Arsizio (VA) and “Scuola dell'Infanzia di Antegnate”, in Antegnate (BG), where the children were tested for their collaboration. The authors thank Melissa Martinelli for her help in testing children and adults and Lucia Gava for helping in creating stimuli and programming the task.

This research was funded by a grant from the University of Milano-Bicocca to the last author and a scholarship from the same University to the first author.

For the last author, Macchi Cassia is the double family name.