Baby's Brain in Week 16
You may have noticed that your baby watches her own hands. This skill takes hold somewhere between 12 and 16 weeks. Although you know that your baby's been able to see since birth, it's taken all these weeks for her to actually take notice of her own hands.
From birth to 6 weeks of age, your baby stared at her surroundings. She would hold a gaze on a bright light or bright object and move her eyes and head together.
Now between eight and 24 weeks, your baby's eyes are moving widely from left to right as she looks around the room, moving her head less and eyes more. If you dangle a toy from a string and move it slowly back and forth, Baby can follow it (see here!) with just her eyes. Not only that, she can also follow you as you move about—which may make sneaking in to check on her during naptime a little riskier these days.
Plus, around now, Baby is developing a visual safeguard: If, by accident, your preschooler tossed a soft baby doll toward his infant sister's face, your baby wouldn't have the physical skill to dodge her head. Instead, she would do the only thing she now physically can to keep the doll from hurting her eyes: She would likely blink like mad.
What the Research Shows
Visually following an object is called tracking. Because a newborn can't yet move independently, a lot of her experiences are with objects that move toward her or away from her. To successfully recognize objects, she has to be able to keep her eyes on them as they move.
Studies show that tracking is initially fairly inefficient. Infants younger than two months show some tracking for brief periods if the target is moving very slowly, but they are only able to follow an object about 90 degrees. A shift occurs somewhere around 12 weeks as babies' tracking becomes skillful rather quickly and they can now follow an object 180 degrees over head.
As babies track objects, they're learning that the shape, size, and color of the item remains constant even when the light, distance, and angle of the view have changed.
To learn about babies' reactions to looming objects, researchers observed the blinking behaviors of three- to four-month-olds when presented with one of three different events: an object moving toward them at a constant speed, which then appeared to explode; an object speedily approaching the baby but slowing as it neared the child's face; and an object changing brightness as it approached the child's face.
The babies only blinked excessively and moved their heads preemptively when the object appeared to approach and explode. The researchers surmised that this was the only scenario of the three in which the babies found cause to protect their eyes.