Infants Begin Understanding Unseen Objects Through Language by 15 Months

Human language enables us to learn new vocabulary about things we have never directly encountered, using contextual clues from conversation to infer meaning. A study by researchers at Northwestern University and Harvard University reveals that this ability begins to emerge as early as 15 months of age.

The researchers conducted a three-phase experiment: first, they introduced infants to familiar words (such as "apple" and "banana") alongside corresponding images; next, they played new words while hiding novel objects (such as a kumquat); finally, they asked the infants to choose the target object from two unfamiliar options (e.g., a kumquat and an egg beater). Results showed that 15-month-old infants could use contextual cues to infer that a new word was more likely to refer to a fruit than a tool, even without having seen the object before. In contrast, 12-month-old infants did not demonstrate this ability, likely due to their still-limited vocabulary, which made it difficult to extract relevant information from context.

The study suggests that infants actively build mental representations of new words based solely on linguistic input, even without direct sensory experience. This early capacity lays a foundation for understanding abstract or non-perceivable entities and highlights the critical role of language in cognitive development. In everyday life, infants frequently encounter words without immediate real-world referents; by 15 months, they are already capable of using context to grasp preliminary meanings, supporting further vocabulary acquisition.

This research provides the first evidence of how infants learn about unseen objects through linguistic environments, offering new insights into early cognitive development.