It is well known in the medical and scientific fields that newborn babies can’t see very well. Initially, all they can make out are faces. Everything else is a blur. As their eyes grow and brains develop, their vision improves. How does that process take place? Do changes in the process lead to visual impairment? Two studies looked into visual development to learn what’s happening and what it means for vision.
Research done at National Eye Institute (NEI) found that the blurry vision of babies helps them to learn to identify shapes and objects. How can this be? When babies are born, the eye’s initial shape doesn’t allow images to be clearly. Babies grow and the eyes change shape, which improves focus. Also, parts of the brain that process visual images are developing and forming connections that allow babies to recognize things. When a child doesn’t experience this phase of blurry imagery, such as a child born with cataracts, he or she can end up having difficulty with complex visual tasks. Once a child with cataracts has corrective surgery, the ability to read letters on an eye chart improves but the child continues to have difficulty with facial recognition.
Scientist believe that achieving high visual acuity after surgery is a factor that moves visual development away from the usual path of visual acuity improving gradually after starting out badly. So, they decided to test what they called “initial impoverishment benefit hypothesis” using a deep convolutional neural network, a computer-based image classification system that is similar to a biological one.
The researchers trained the network with a database of facial images and then they simulated three scenarios. First, they copied the normal visual developmental path of blurry to high resolution images. Second, the order was reversed, high resolution to blurry images. Third, the network was trained only on high resolution images. They found that the network performed better when trained on blurry images followed by high resolution images. During this scenario, the network expanded the size of its receptive field, the area detected by its sensors. When it saw a blurry image, the image lacked detail, so the network sought more information by enlarging the size of the receptive field and this improved the network’s ability to recognize patterns. Yet, the performance was poor when the training involved high resolution only. The findings suggest that children who have cataract surgery may benefit from a gradual improvement in visual acuity.
Recognizing Faces and Learning to Read
Would you believe that brain regions activated in children when they see limbs are activated when they see faces or words when they grew older? Yes, it’s true and research at Stanford University demonstrated that brain regions that serve in a functional role, later help process written words.
The study involved 30 children, between the ages of 5 and 12. Scientists used functional MRIs to study areas in the ventral temporal cortex that are stimulated by the recognition of images. The subjects viewed images from 10 categories including words, body parts, faces, objects and places. The areas of the ventral temporal cortex that showed stimulation were mapped and the changes in intensity and volume were measured on the MRI tests over the years.
The results in the regions in the ventral temporal cortex that corresponded to face and word recognition increased with age and limb recognition in the same region decreased by one half. According to researchers, the decreased limb selectivity is linked to the increase in word and face selectivity, which provides evidence of cortical recycling during child development.
Researchers feel that cortical recycling in the ventral temporal cortex reflects adjustments to visual demand during childhood. Infants focus on faces. Toddlers learn language, explore objects and interpret gestures. Once children start school, word recognition becomes important as they learn to read.
These two studies showed that there is a lot going on in a child’s brain when it comes to vision. Now if there was only a way to have kids do their chores and schoolwork without nagging.