We know from previous NIRS studies, for example, that while babies learn new words, their left frontal lobes are highly active. This helps us understand better how infants’ developing brains process the numerous impressions from their environment. Before the session we put a soft headband on babies’ head that is designed specifically for infants and is widely and safely used in numerous institutions around the world. The band gives out weak, harmless infrared light and measures how much of this light is reflected by different areas. During NIRS studies we usually show babies short videos or pictures on a screen. We record the whole session on video for later analysis.