Speech and touch are fundamental ways of communicating emotions in infancy and early childhood. However, little is known about emotional processing in children. The aim of this dissertation was to examine emotional speech and affective touch processing in children less than two years of age. Study I was a systematic review on emotional processing studies done using near-infrared spectroscopy in children up to two years of age. Study II examined two-monthold infant brain responses to different types of emotional speech using diffuse optical tomography (DOT); and Study III explored their association with selfreported maternal pregnancy-related anxiety. Study IV investigated affective touch processing in two-year-old children by using DOT. 

Bilateral temporal cortical activation was most commonly reported in response to emotional stimuli in children less than two years of age in earlier studies using NIRS (Study I). In two-month-old infants, we found a positive HbT response to happy > neutral speech in the left posterior superior temporal sulcus (pSTS) and happy > angry speech in the left superior temporal gyrus (STG) and pSTS (Study II). We found that infant HbT responses to sad speech, over left STG and midinsula, correlated negatively with pregnancy-related anxiety symptoms at gestational week 24 (Study III). We observed a positive HbT response to affective touch in the left inferior frontal gyrus (IFG) and left middle temporal gyrus in two-year-old children (Study IV). 

Our results demonstrate that two-months-old infants show differential activation to happy speech as compared to neutral and angry speech. In addition, twomonth-old infants’ attenuated processing of sad speech associates with maternal prenatal pregnancy-related anxiety during mid-pregnancy. Lastly, affective touch is processed in two-year-old children in the key components of the “social brain”, and thus affective touch probably plays an important role in forming social bonds between children and their caregivers.