Evolving object concepts in the adult brain: An electrophysiological investigation.

This study investigated how the gradual acquisition of object meaning influences different phases of object recognition. Using an interleaved learning and testing procedure, participants were repeatedly exposed to unfamiliar, rare objects while learning about their meaning and function. Across multiple test sessions, event-related brain potentials (ERPs) were recorded to examine changes in early perceptual processing (P1) and later integrative phases of object recognition (N400, late positive complex/LPC) for initially unfamiliar versus well-known objects. Initially, behavioral and ERP differences between rare and familiar objects were pronounced but gradually diminished with learning. For tasks in which object meaning was irrelevant (familiarity classification and naming), increased object knowledge was reflected in a posterior negativity in the N400 window. When object meaning was directly task-relevant (semantic classification), detailed knowledge acquisition was tracked by a later centroparietal component in the LPC window (late relatedness effect). A follow-up test 6 months later showed that these effects were not only remarkably stable but continued to evolve beyond the training period. In contrast, early perceptual processes (P1) showed limited sensitivity to the accumulation of object-specific semantic knowledge. Overall, the findings demonstrate that repeated visual exposure and incremental learning facilitate the deep integration of novel objects into existing semantic networks.