Abstract
During the first two years of life, human infants develop the ability to coordinate their head/eye movements and move through the world, first by rolling, then crawling and eventually walking. These changing motor abilities have an impact on their visual experience. We examined how the statistics of visual experience change over the course of motor and visual development. We analyzed video data gathered from cameras mounted on the heads of infants (N=89, age=1 to 26 months) in their home environment. Image statistics were calculated for each video frame, including RMS contrast, orientation, spatial frequency, and contrast energy. We also measured the frequency of large-head-movements. Using deep learning, and epi-polar geometry, we reconstructed the angular camera movement between video frames. We treat these estimates as an approximation of the head movements. Most notably, between 1 and 11 months, there was an increase in the occurrence of large-head-movements, followed by a slow decrease through 26 months. The global RMS contrast was uniform across age groups, but the concentration of RMS contrast towards the center of the video frames was more pronounced in older infants, suggesting that older infants select high-contrast information as they become more capable of manipulating their bodies and their environment. We saw no consistent difference in the orientation content across age. This was counter to our hypothesis that the typical biases (horizontal/vertical) in orientation statistics in natural images would emerge/tighten as infants developed postural stability. However, 26 months is still relatively early in the development of walking and postural control. Future work will include comparable data from older children or adults to determine if the orientation content changes with this increased stability or if the variability due to infant postural instability is small relative to the natural variability of orientation content due to the self- motion observed in adults.