While learning English, learning new words from context is probably not the hardest part: for example, if we hear "he's making coffee in the kitchen", "my kitchen is very small" and "I have the same table in my kitchen", it's easy to identify that the same word appeared in each sentence as it was present in the same form. This is not the case in languages like Hungarian (agglutinative languages): a verb or a noun (such as "konyha", kitchen) can have hundreds of possible forms, as it can be combined with a huge number of suffixes. For example, in the kitchen (a konyhában), my kitchen (a konyhám), or in my kitchen (a konyhámban) all sound differently, moreover, all these suffixes change the form of the word stem. For someone who is just learning Hungarian, it must be difficult to recognize all these versions and to realize which word they belong to. So how do Hungarian infants do that?

Kovács Ágnes (CEU), Ladányi Enikő (Vanderbilt University) and Gervain Judit (CNRS) investigated this question together. In a study, they played 15-month-old Hungarian infants simple sentences including a new (pseudo)word (e.g. púr) always paired with a familiar suffix (e.g. púrban – "in púr" in English). The researchers wanted to find out whether this introduction makes infants able to recognize the word stem itself later, even though they have never heard it alone. To test this, they sat babies at an equal distance from two loudspeakers. One of the loudspeakers played the word púr, now without a suffix, while the other one played a new, unfamiliar word (gál) in short, non-overlapping intervals. The scientists measured how long 15-month-olds looked at each loudspeaker. Babies paid more attention to the loudspeaker from which they've heard the novel word (gál). This suggests that they recognized the word púr from before and therefore found the other one more interesting. In other words, the researchers found a novelty effect.

Does this mean that babies were able to extract the word stem „púr" from the „púrban" form and remembered it as an individual word, or was it simply familiar to them as a syllable that they've heard before? To reveal more about how babies processed the complex word form, the researchers also checked what happens when infants hear the word stem in combination with another pseudoword, e.g. dag. There's no meaningful part of púrdag that babies would have heard before, so in this case, they couldn't be sure whether púr is an individual word or exists only in combination with –dag. If babies heard the word púrdag in simple sentences at the beginning of the study, they paid equal attention to the pseudowords púr and gál later. This means that the novelty effect observed in the previous condition of this study cannot be explained by syllable familiarity alone – there was no difference in this regard between the two conditions -, rather, it is determined by babies' understanding of púr as an individual word.

This tells us that babies whose mother tongue is rich in suffixes develop an ability to analyze complex word forms and identify the word stem even without hearing it in itself beforehand. This sophisticated process is already present at an age when babies have typically just learned to say their first words. This discovery, once again, reveals that there is much more going on in their minds than adults would imagine.

Original paper: Ladányi, E, Kovács, ÁM, Gervain, J. How 15-month-old infants process morphologically complex forms in an agglutinative language? Infancy. 2020; 25: 190– 204. https://doi.org/10.1111/infa.12324