I see you: The role of visual processing in social behavior across development

Children show an enormous (social) development from a highly dependent newborn who barely makes contact towards a socially skilled person who can usually take care of him- or herself. The general aim of the present dissertation is to investigate the role of visual processing in social behavior across typical development, with a focus on infancy. For visual processing, the focus is on the role of lower and higher spatial frequency information, related to the configuration of a face and the details in a face respectively. For social behavior, the focus is on gaze-cued orienting of attention, emotion discrimination and quality of parent-child interaction. The results from the present dissertation suggest that both lower and higher spatial frequency information are sufficient for gaze-cued orienting of attention in adults. When these results are compared to previous results in children, there seems to be a change across development, with a primary role of lower spatial frequencies in children but not in adults. We aimed to extend these findings to infants as well. However, there was no evidence for gaze-cued orienting of attention in the infants. Hence, the role of spatial frequencies could not be investigated. The present results suggest that gaze-cued orienting of attention in infants is not very robust and/or more specific than previously thought. The next two studies indicated specific roles for the lower and higher spatial frequency information in emotion discrimination in infancy. 5-month-old infants could only discriminate fearful from neutral faces in the lower spatial frequency condition. For most of the investigated measures of emotion discrimination (i.e. face-sensitive Event Related Potentials), 10-month-old infants could only discriminate happy from neutral or fearful faces in the higher spatial frequency condition. These findings are placed within current models on the underlying brain mechanisms of face processing. Possibly, the subcortical pathway via the amygdala, and the cortical pathway via the visual cortex each play different roles in the development of emotion discrimination. We also showed that there was no evidence for a relation between emotion discrimination of fearful faces (based on only lower spatial frequency information) and social interaction quality (parent, infant and dyadic aspects). Lastly, the test-retest reliability of the used measure of emotion discrimination (i.e. face-sensitive Event Related Potentials) was investigated. Reliable scores for each individual are needed when investigating emotion discrimination over time and in relation to other variables, such as quality of social interaction. The results show adequate test-retest reliability of the overall face-sensitive Event Related Potentials, but not for the effects of emotion and spatial frequency content on these Event Related Potentials. In conclusion, the present dissertation provides indications that across development there is a relation between social behavior and visual processing of lower and higher spatial frequency information in a face. However, in order to further understand visual and social development, longitudinal large-scale studies that use reliable measures are warranted. These studies should investigate further how differences in visual processing have subtle cascading effects on social behavior, and other domains, across development