Categorization of visual objects in early childhood

Importance

Categorization is the basis of thinking and reasoning. Through infant gaze analysis, we describe the trajectory by which visual object representations in infancy gradually correspond to categorical object representations as mapped on the visual cortex of adults. Using a methodological approach that compares the results obtained with behavioral and cerebral measures in infants and adults, we identify the transition from a visual exploration guided by perceptual salience to an organization of objects by categories. , which begins with the animate-inanimate distinction in the first months of life and continues with a surge of biologically relevant categories (human bodies, non-human bodies, non-human faces, small natural objects) throughout the second year of life. life.

Summary

Humans make sense of the world by organizing things into categories. When and how does this process begin? We investigated whether categories of real-world objects that emerge spontaneously during the first months of life correspond to categorical representations of objects in the human visual cortex. Using eye tracking, we measured the differential gaze time of 4-, 10-, and 19-month-old children when they looked at pairs of images belonging to eight animate or inanimate categories (human/non-human, faces /body, life size large/small, natural/artificial). Taking infant gaze times as a measure of similarity, for each age group we defined a representation space where each object was defined relative to others of the same or different category. This space was compared to hypothesis-driven and functional MRI-based models of visual object categorization in adult visual cortex. Analyzes across different age groups have shown that as infants grow, their visual behavior matches neural representations in increasingly larger portions of the adult visual cortex, suggesting increasingly progressive recruitment and integration. functional spaces distributed over the visual cortex. Additionally, the results characterize the visual categorization of infants as a gradual two-step process. Between 4 and 10 months, visual exploration guided by salience gives way to organization according to the animate-inanimate distinction. Between 10 and 19 months, a categorical leap leads to a mature organization. We propose that these changes underlie the coupling between seeing and thinking in the developing mind.

Footnotes

    • Accepted December 30, 2021.
  • Author contributions: research designed by CS, J.-RH and LP; CS and EA did research; CS, EA, J.-RH and LP analyzed the data; and CS, J.-RH and LP wrote the article.

  • The authors declare no competing interests.

  • This article is a direct PNAS submission. GC is a guest editor invited by the Editorial Board.

  • This article contains additional information online at https://www.pnas.org/lookup/suppl/doi:10.1073/pnas.2105866119/-/DCSupplemental.

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