Visual object categorization in infancy

Abstract

Humans make sense of the world by organizing things into categories. When and how does this process begin? We investigated whether real-world object categories that spontaneously emerge in the first months of life match categorical representations of objects in the human visual cortex. Taking infants' looking times as a measure of similarity, we defined a representational space where each object was defined in relation to others of the same or different categories. This space was compared with hypothesis-based and fMRI-based models of visual-object categorization in the adults' visual cortex. Analyses across different age groups revealed an incremental process with two milestones. Between 4 and 10 months, visual exploration guided by saliency gives way to an organization according to the animate-inanimate distinction. Between 10 and 19 months, a category spurt leads towards a mature organization. We propose that these changes underlie the coupling between seeing and thinking in the developing mind.

Visual category representations in the infant brain

“…Representations in infants emerged later, slower, and lacked particular components of feedforward and recurrent processing, possibly related to immature myelination 30 and synaptic connectivity 31 . Nevertheless, representations in infants and adults shared large-scale temporal dynamics that encoded visual category information similarly, consistent with previous showing partly adult-like behavioral 3,5,7,15 and neural 19,20 category sensitivity in the first year of age.…”

“…The ability to recognize and categorize visual objects effortlessly and within the blink of an eye is a core human cognitive capacity 1,2 that develops through learning and interaction with the environment. Behavioral research in infants using looking times 6,7,15 and neural markers of attention provides evidence for visual category processing 16 and learning 5,17 already within the first year of life.…”

Acceleration of information processing en route to perceptual awareness in infancy

“…One consequence of this developmental change could be a change in the content of mental representations: less sensory information is lost and more information can be integrated, yielding richer, more sophisticated cognitive representations and behaviors. 31…”

Functionally analogous body- and animacy-responsive areas in the dog (Canis familiaris) and human occipito-temporal lobe

“…Further, dividing stimuli into an animate vs. inanimate dimension is one of the first visually salient categorizations formed by human infants [68]. In this way, animacy representation provides the first building block for more complex visual categorizations such as faces vs. bodies.…”

“…Studies show that dogs target animate agents when, for example, presented with images of wild animals, humans or dogs embedded in natural landscapes [67] or of social interactions between humans and dogs [68]. Further, dividing stimuli into an animate vs. inanimate dimension is one of the first visually salient categorizations formed by human infants [69]. In this way, animacy representation provides the first building block for more complex visual categorizations such as faces vs. bodies.…”