Background and research interests
“I did not plan on going into linguistics at all. I started with a BA in Language and Communication because I was convinced I was going to be a journalist at the time. I was writing for a newspaper, freelancing, and I thought that program would be perfect for pursuing that career. But one of the courses I took was an introductory course to linguistics, and this really caught my attention. I changed my plans and decided to do a minor in language variation and language development, including an internship with the Meertens Institute. I met all these people who were super excited about the things they were doing, and I thought – I want to be like these people, how do I do it? I started an MA in Dutch and filled it all with Linguistics courses, and then I went away from the university for a year to work. But I missed school, so I went back for a year to do the RMA. In the meantime I was applying for PhD positions, when suddenly this NWO project came up and I got the job.”

“I like language for multiple reasons. I enjoy puzzles and especially questioning things we take for granted. Language is something everybody learns and uses all the time, yet there’s a lot of weirdness. Plus, language is something that makes us human. Even though any other creature can do very impressive things, only humans have language in the way that we do. You can tell a person by the way they walk in the hallway, but also by the way they talk. I can read something and sometimes know who must have written it. So language doesn’t only say much about who we are as a species, but also who we individually are as people.”

“This is also one of the reasons why I am interested in child language. From an evolutionary perspective, human babies are very problematic. Foals or calves can walk around immediately when they are born, guinea pig pups can forage for their own food, but human babies are completely helpless. Even older kids are still relatively vulnerable. For some reason, though, they are super good at learning a language — something we seem to get worse at as we get older. I am impressed by the way children can do that, it tells us something about how they learn, and about how language works.”

As easy as one, two, three?
“My PhD project is about how children learn number words and how they develop numerical concepts. There are cardinal numbers, such as one, two, three and four, but also ordinal numbers, such as first, second, third, fourth, and my research question is specifically about how these ordinal numbers are acquired. There has been decades of work on the acquisition of cardinals, from which we know that in order to understand cardinals, children need to learn a set of counting principles. They need to understand that if you count from one to ten, you cannot skip or repeat numbers, that you have to say all the numbers in the right order, and finally that when you get to the end that says something about the group as a whole, and not just about the individual item you counted as ‘number six’. This process takes a lot of time.”

“Part of that process involves adjoining two different kinds of number systems that individually don’t give us exact understanding of number systems, but together, do. There is the OTS – the Object Tracking System – which is not really used for counting, but for keeping track of things. This system is good for small quantities up to four, for plus and minus one, for comparing 1 versus 2 and 2 versus 3, but interestingly enough it cannot distinguish 1 from 4. We also have a different number system, the approximate number system – the ANS – which is better for larger numbers, but has to do everything approximately. So this lets you estimate the difference between 60 and 80, but wouldn’t give you the difference between 80 and 81. However, us human beings are capable of conceiving a precise concept such as 81. The common argument is that we can merge, or bridge the gap between, the big number system that is vague, and the other small number system that is exact, by using language.”

“The ordinal domain is one place where you can clearly see this interaction between language and number, because here we see the ordinal suffixes showing up, adding a clear contribution to the cardinal number. And then you can ask the question: does language influence the way we learn these ordinals, or do children use the same strategy as they use for cardinals – so do they learn the first four numbers by rote, before they understand how counting works? ”

“My research showed that Dutch and English-speaking children only acquire ordinals once they have acquired the counting principles I mentioned earlier, so they really need to be competent counters. Then they can pick up the ordinal system. First, ‘first’ is acquired. This word is different for various reasons – it is the first in the list, it doesn’t require counting, it is much more frequent than the other ordinals, and there’s reason to say it’s not even an ordinal at all, but a superlative. Regular ordinals are learned next. In Dutch, these are 'second' (tweede), and 'fourth' (vierde) – This means that derde (‘third’) is skipped, and higher numbers are acquired a bit later. In English, second, third and fifth are irregular, and fourth only becomes regular when you find more evidence for the rule in sixth and seventh. Only after these regular forms are acquired, do children use and comprehend the correct irregular forms. This means that although cardinal numbers are acquired in the order of the count list, ordinal numbers are not.  Instead, kids learn ordinals using a rule: a cardinal plus –th makes an ordinal in English. This shows language really does influence the way we learn these ordinals.”

“This leaves us with a couple of questions. First of all, we should ask to which extent this is expected. Although not a single parent or teacher is surprised when I tell them that children say driede instead of derde or two-th instead of second, this behavior is very different from what we typically see in the acquisition of irregular morphology. For example, if we look at the past tense, we see a U-shaped development. Initially children say went, then they learn the rule and start to say goed as well, but eventually they learn that there are exceptions to the rule, and go back to saying only went. If rule-based learning worked the same way for ordinals, we would expect derde-driede-derde or second-twoth-second in their own speech. However, then we wouldn’t expect for children not to understand the word derde: it’s not like kids who say goed suddenly forget what went means. But that is something that clearly happened for ordinals in my experiment: ask for driede (‘threeth’) and kids are totally fine, ask for derde and they don’t know. I therefore argue that the acquisition of ordinals follows a different pattern, where they first use the structure to comprehend what the different ordinals means, before they are able to learn irregular forms.”

“You may still ask why Dutch kids understand tweede ‘second’ and vierde ‘fourth’ , but subsequently fail on higher ordinals. There I argue that it is not coincidental that the boundary is at four. Children can do the linguistic math for two and four within the OTS domain, without having to involve the ANS. But to do higher ordinals, you need to combine both of your number systems and interpret the linguistic form. That is an extra step, and thus it makes sense that this takes more time. English-speaking kids have no choice – evidence for the rule only comes after sixth, so when they have competently merged the two systems. So for them, the challenge is different. Dutch children are trying to learn the ordinal rule while they are still figuring out how to merge their number systems, whereas English children have already learned how to merge their number systems before they can even have access to the rule.”

“To conclude, there is a lot involved in the acquisition of numerals. There is rule learning, conceptual knowledge, there is merging number systems, and it takes years for all of that to fall into place. We have this expression saying that it’s as easy as 1-2-3, but when you think about it, even 1-2-3 is not that easy at all.”

Future research
“This research opens a lot of questions for further research. Although the acquisition of cardinal numbers has been investigated in many languages, not much is known about ordinal numbers, so if anyone is interested in extending this research to other languages, I would definitely encourage it. However, I am also interested in the linguistic side of this rule-learning part. For the plausibility of my hypothesis it is important to find other things in language that are learned this way. Perhaps there are other things just like number that are conceptually too hard to be acquired the way the past tense is. That is something I would like to investigate.”

“My future research could also involve a completely different topic. I am interested in language systems and language processing generally, and not only in the mind of the child, so I am still thinking about what kind of proposal I want to write. But I am generally very easy to excite for things, so if someone passionate shows up with a new idea – a cool language variation project, or something related to bilingualism, or music and language, I could be really into any of that. The thing that got me excited about my NWO project in the first place was the broad interdisciplinary perspective, so I am very interested in collaborations of all types.”

Teaching
“Beside my PhD project, I have also been teaching, something I have been doing ever since my MA, when I was a Dutch teacher in The Hague for a while. I like teaching, because to me there is no point in knowing something if you do not get to share it . Teaching makes me and my research feel slightly more relevant, because it lets me contribute to society. I also really like seeing students join a class at one level, and grow to be so much more– sometimes becoming completely different people. That is really satisfying. Plus, students have also taught me plenty, too.”

“I think it is important for researchers to be able to translate their research for non-specialists, to give it back to society, whether that is by valorization, by teaching or something else. A big part of our research is funded by public money, and we should try to give this knowledge back in return, so that people know what’s being done with it. It is easy to be invisible and we should try to be more visible.”