Morphemic regularity may help babies acquire concepts like number and gender

Research has long shown that, whatever their L1, infants learn words at much the same rate and in much the same order. The same may not be true, however, for the smallest unit of meaning: the morpheme. A study from Manchester University suggests that speaking a highly inflected language may offer an advantage.

The study, led by Alissa Ferry, found that Italian infants as young as 12 months can understand grammatical gender and some elements of number. By contrast, children who speak English, a language with few inflections and no grammatical gender, don’t understand plural morphology until they are twenty months old, according to previous studies.

Ferry’s team focused on morphemic regularities where the same morpheme or group of morphemes mark particular grammatical concepts such as number or gender. They wanted to examine whether infants could link these regularities to the grammatical concepts they convey, and because they suspected morpheme acquisition might be language led, they chose infants whose L1, Italian, had a rich inflectional morphology.

In Italian regular nouns, the plural is formed by changing one morpheme: the final vowel. Regular nouns fall into a number of groups, but one predominates, and is used in over 70 per cent of cases, according to this paper. They follow a simple pattern: feminine nouns end in –a in the singular and change to –e in plural, masculine nouns change from –o to –i.

This group of nouns includes a number of terms for different types of people, and each one uses the same word root, or lemma, for example ‘bambin’ is the word root for baby and this lemma is then marked with a morpheme showing gender and number: bambina (baby girl), bambino (baby boy), etc.

It is tempting to conclude that Italian babies understand plurals earlier than English-speaking ones simply because the system is simpler. As the table here shows, however, the advantage is far from clear. Italian uses fewer lemmas but more morphemic patterns.

In addition, the definite article is more complex in Italian. It is also always marked for gender and number and the feminine form follows the most common noun pattern: the singular form la ends in –a (though changes to l’ before a vowel, as in l’amica), the plural form ends in –e, le, and is also used in front of vowels. The masculine is less regular.

Generally, the singular il becomes I in the plural. However, l’ is used before vowels and lo in front of certain consonant clusters, and the plural of both is gli.

This irregularity was one factor behind the decision to use Italian speakers for the study: if morphemic regularity is key in acquisition, then infants should acquire the regular female forms earlier than the irregular masculine ones.

The study recruited 85 Italian infants age 12, 18 and 24 months to see when they could use morphemes to differentiate number and gender.

The Italian infants were shown pairs of pictures of males, females or both, using word roots like ‘bambin’ where number and gender are formed by changes in one morpheme, the final vowel. At the same time, they were given instructions in Italian: for example, ‘Look at the bambina (baby girl)!’ or ‘Do you see the bambine (baby girls)?’ The eye movements were tracked throughout, so if the child understood which picture matched the spoken language, they should look longer at that picture.

Ferry was surprised to find that even the 12-month-old infants could distinguish gender and number – with one exception – and there was no discernible difference across the age groups. The exception related to the less consistent male case. Infants in all age groups could easily distinguish linguistically between men and women and between one or more women – but not between one or more men.

Re-tested a year later, the infants still couldn’t distinguish the male plural. The researchers ascribe this to morpheme irregularities in the masculine article, which supports the morphemic regularity hypothesis. The authors suggested the study should be rerun in Spanish, which does not show such irregularity in the masculine form.

An alternative explanation could be that the infants were confused because, as in all Latin languages, the masculine plural is used not only for all male groups like older men, but for mixed sex groups, too.

REFERENCE

• Ferry, A., Nespor, M. and Mehler, J. 2020. Twelve to 24-Month-Olds Can Understand the Meaning of Morphological Regularities in Their Language. Developmental Psychology, 56 (1): 40-52.