Cat or Cats? Italian-learning infants understand singular/plural rules sooner than English-learning infants

After finishing my PhD in the United States, I moved to Italy to do research studying infant language acquisition.  This meant that I had to learn some Italian!  One of the first things we learned in Italian class was that all Italian nouns have gender (male/female) and they have to mark whether it is singular plural. This is already a bit trickier than English, since our nouns don’t have gender (so I had to learn that apples are feminine and tomatoes are masculine)! But it got even trickier because Italian has you mark these distinctions in lots of different parts of language! 

In English, for example, if I am talking about THE RED APPLE or THE RED APPLES, whether I am talking about one apple or many apples is distinguished by whether there is an S at the end of apples.  Simple!  But, the same phrases in Italian are LA MELA ROSSA and LE MELE ROSSE. You have to keep track of it is three different places!  In Italian, articles (the “the”), nouns, and adjectives all have to mark whether it is male or female and whether it is singular or plural.  To me, this seemed like quite a lot of work and it was hard to keep track of, especially in longer sentences! 

As a language researcher, I wondered how this affected children learning Italian.  Previous work showed that English-learning children start to learn the meaning of the –s marker in English around their second birthday.  I wondered, would Italian children be slower, because (like me), they found it hard to track the differences in so many places?  Or, might they even be faster, since they had so many reminders about whether the noun singular or plural (and masculine or feminine)? Or, maybe it doesn’t really matter at all.  Maybe you start to figure out what plurals are at the same time in every language.  So, as a language researcher, with access to Italian-learning babies, I decided to test some and find out!  

I set up a study in which I showed 12- to 24-month-olds pictures of faces.  We used faces, because that allowed us to look at whether children understood gender differences (genders for objects are arbitrary, but genders for people align with their biological gender) and number differences. We would then show infants two images side-by-side (for example, one girl and two girls) and then asked them to look at either the girl (La bambina) or the girls (Le bambine).  We found that even as young as 12 months, infants seemed to succeed on the task!  This meant that all that redundancy (that was so hard for me when I was learning Italian) actually seemed to help infants figure out the rules faster!  They start to understand what plurals mean an entire year before English learners!  And they understand the gender differences too!

Interestingly, we also found that the masculine rules are a bit trickier to learn, because they are less consistent in Italian.  For masculine rules, there is an extra rule that the article (the “the”) changes based on the next sound (sometimes it’s Il for singular and I for plural; sometimes it’s Lo for singular and Gli for plural).  This seems to take longer to learn because the patterns are less obvious and less consistent than the feminine rules (which don’t have these funny extra rules). This seems to suggest that easy, obvious rules are learned faster.

Previous work shows that children seem to learn words in their language at about the same rate, no matter what language they are learning.  This work shows that children seem to learn grammatical rules differently, depending on the language. (and what the easy and obvious rules are in that language). While we find that Italian-learning babies pick up the singular/plural rule faster than English-learning babies, there are likely other rules that English-learners figure out before Italian-learners.  This has implications not only for understanding how children learn language in general, but also for understanding how our understanding of “typical” language development might differ depending on the language being learned!   Stay tuned as we investigate how these patterns might differ in other languages as well! 

Find out more about this study in our paper:

Ferry, A., Nespor, M., & Mehler, J. (2019). Twelve to 24-month-olds can understand the meaning of morphological regularities in their language. Developmental psychology.