Labelling abstract representations in 5 month-old infants
Language acquisition relies on the ability to integrate different features of a given percept into a unified mental representation that can be mapped onto an arbitrary symbol. The human mind can thereafter operate in an abstract space, developing uniquely complex systems of knowledge such as language, mathematics or music. In a series of three EEG experiments, we explored 5-month-olds’ abilities for monitoring several abstract representations, and pairing each with an arbitrary sensory label. In a first experiment, infants had to categorize trisyllabic words according to their structure (AAB/ABA) in order to discover a systematic association with the subsequent sensory label. After a brief exposure to the abstract patterns consistently followed by their labels, infants were introduced to some incongruent pairings. Neural recordings revealed not only a late surprise effect in response to incongruent pairings, but also a priming effect, with stronger early sensory activations to congruent pairings. Inspection of the silent period between the structure and its label additionally revealed the build-up of anticipatory activity before the occurrence of the label. These results established that infants can form robust mental representations for abstract structures, and operate on those in a pairing task. The second experiment replicated and extended these results showing that infants can flexibly label abstract representations within and across sensory modalities. In a final experiment, we explored the nature of the acquired association. Interestingly, infants’ pairing abilities went beyond mere temporal contingency, as they spontaneously reversed the acquired associations. The encoded representations therefore possess attributes to enter a symbolic system.