Face recognition is one of the first visual skills your baby learns - a 2012 study out of the Stanford Vision and NeuroDevelopment Lab says that babies can process faces almost as well as adults do by the time they’re around 4 months old. Other studies suggest that babies can recognize their parents or primary caregivers’ faces within days or weeks, and their mothers’ faces sometimes within hours of birth, depending on how awake and attentive they are.
Once your baby starts building the skills to differentiate between faces, which she starts working on pretty much as soon as she is born, the biggest factor in when she starts to recognize the people in her life has to do with how often she sees them, and for how long. The first people she recognizes are generally her parents or primary caregivers - the people who feed her, and whose faces she gets to see up close and personal for significant amounts of time even when she’s young enough that she can only see approximately 8 to 12 inches from her face. This means that if your baby only sees her grandparents once every couple of weeks for a few hours, it might be a few weeks until she starts to recognize them, while family or friends who she sees once a week will make it into your baby’s mental roster of friendly faces a little faster. And people who drop into her life every day, even if they’re, say, the crossing guard near her daycare, rather than an adoring relative, will be someone she recognizes pretty quickly.