Infants’ ability to relate words to objects at 12 months linked to language skills at 18 months
New research from Northwestern University shows that how precisely a 12-month-old links spoken labels to object categories predicts the size of that child’s vocabulary both at 12 months and again at 18 months. In other words, infants who already use names to distinguish categories of things—rather than grouping objects only by visual similarity—tend to understand and produce more words later in the second year of life.
The study, conducted by Brock Ferguson, Mélanie Havy and Sandra R. Waxman in the psychology department at Northwestern’s Weinberg College of Arts and Sciences, appears in the open-access journal Frontiers in Psychology. The authors report that individual variability in infants’ early ability to connect language to categories provides an informative early index of vocabulary development.
Ferguson, the lead author and a doctoral candidate in cognitive psychology, describes the experimental logic with a simple analogy. Imagine a visit to the zoo’s primate house, with gorillas, chimpanzees and monkeys all on display. Although these primates may look broadly similar, adults distinguish them using different names. In the lab, researchers present infants with objects and different labels to test whether babies treat items as members of the same group based on shared names or instead group them by visual features alone.
Infants who treat differently labeled items as belonging to the same group—effectively relying more on appearance than on distinct labels—tended to have smaller vocabularies. By contrast, infants who showed a precise mapping between labels and categories at 12 months already understood more words at that age and continued to show stronger vocabulary performance at 18 months.
Cognitive development in infancy covers a range of skills including memory, perception, problem solving and language acquisition. This study focuses specifically on the early link between words and categories—a basic cognitive skill that underpins how children learn new words. According to Sandra Waxman, the Louis W. Menk Chair in Psychology and a professor of cognitive psychology, the finding is important because it connects infants’ performance on a controlled cognitive task to measurable progress in learning words.
Researchers working at the Project for Child Development have previously demonstrated that talking to infants—even before they can speak—supports language and cognitive growth. The current finding builds on that work by identifying a measurable early behavior that relates to subsequent vocabulary growth. Ferguson notes that this offers a first step toward using targeted cognitive assessments to identify infants who might be at risk for later language delays.
Key points:
- At 12 months, the precision of infants’ links between words and object categories predicts vocabulary size at both 12 and 18 months.
- Infants who already use labels to distinguish categories tend to know and later produce more words than infants whose label-category links remain broad.
- Talking to infants before they speak supports language and cognitive development; these findings could inform early screening and intervention efforts aimed at narrowing vocabulary differences across children.
Source: Erin Meyer, Northwestern University
Image Source: public domain image used for illustration
Original Research: “The precision of 12-month-old infants’ link between language and categorization predicts vocabulary size at 12 and 18 months” by Brock Ferguson, Mélanie Havy and Sandra R. Waxman, Frontiers in Psychology. Published online August 31, 2015. DOI: 10.3389/fpsyg.2015.01319
Abstract (summary)
Infants initially form broad associations between language and object categories that become more refined during the first year. In a longitudinal design, the researchers tested whether variability in the precision of these associations at 12 months relates to later vocabulary. Infants showing a precise mapping between labels and categories at 12 months understood more words at that age and, six months later, also knew and produced more words than infants whose mapping remained broad. The authors conclude that individual differences in the precision of label–category links at 12 months provide a reliable window into early vocabulary development and discuss possible causal pathways for this relation.
This research highlights an early cognitive marker that correlates with language progress during a critical period of development. While the findings do not prescribe specific interventions, they support the value of responsive, language-rich interactions with infants and suggest a potential route for early identification of children who might benefit from additional language support.