Perceptual reorganisation from prior knowledge emerges late in childhood

Perception in the mature human visual system relies heavily on prior knowledge. Here we show for the first time that prior-knowledge-induced reshaping of visual perception emerges gradually, and late in childhood. To isolate the effects of prior knowledge on vision, we presented 4-to-12-year-olds and adults with two-tone images, which are degraded photos that are hard to recognise on first viewing. In adults, seeing the original photo causes a perceptual reorganisation leading to sudden, mandatory recognition of the two-tone version - a well-documented process relying on top-down signalling from higher-order brain areas to early visual cortex. We find that children younger than 7 to 9 years, however, do not experience this knowledge-guided shift, despite viewing the original photo immediately before each two-tone. To assess potential computations underlying this development we compared human performance to three state-of-the-art neural networks with varying architectures. We found that the best-performing architecture behaved much like 4- to 5-year-old humans, who display a feature-based rather than holistic processing strategy akin to neural networks. Our results reveal a striking age-related shift in the reconciliation of prior knowledge with sensory input, which may underpin the development of many perceptual abilities.