Most children acquire their mother tongue seemingly without any effort, but there are differences in how fast they acquire it. While some children may already say their first words when they are one year old, others might not speak until they are older. These differences can stem from the environment of the child, for example, the way the parents speak to their child, but also the child’s own abilities, for example, how many words they understand already or how fast they can recognise words, can play a role. The latter is called speed of processing.
Past research has shown that how many words infants know is related to how fast they process words. However, we do not know why these two aspects are connected. On the one hand, it might be that if infants recognise familiar words quickly, they might be better at learning new words. On the other hand, it could be that if infants know a lot of words already, they are also faster in processing incoming words. In this thesis, Julia investigated the relationship between the words infants know and how fast they process words as well as how parental speech might affect infants’ individual processing abilities.