Baby talk is more than just bonding: chatting with your infant spurs important brain development that sets the stage for lifelong learning, researchers say.
And while high-pitched, sing-song tones may capture your baby's attention, the best way for them to learn is to be spoken to like adults. At least when it comes to vocabulary and sentence structure.
"It's not just how much speech you get, but the kind of speech you get," said Erika Hoff, a psychologist at Florida Atlantic University.
"Speech needs to be rich and complex."
Talking to babies is so important that researchers say it is a major reason why children from disadvantaged backgrounds perform poorly in school.
By the time they reach the age of five, the children of low-income, poorly educated parents typically score two years behind their privileged peers on standardised language tests.
These differences can also be measured in the brain, said Columbia University neurologist and pediatrician Kimberly Noble.
The human brain experiences incredible growth in its early years.
By the age of three, it has formed 1,000 trillion neural connections - the links between cells that help the brain do everything from picking up a stick to remembering song lyrics.
"A child's experiences really come into play to determine whether those connections strengthen or are dropped or pruned," Noble told reporters at the American Association for the Advancement of Science's annual meeting.
Noble and her colleagues compared the brains of children with low socioeconomic status to those whose parents are highly educated and paid well.
While they found differences in the core cognitive systems that support social skills and memory, the largest disparities were in the brain structures for language development.
"With increasing age, children from higher socioeconomic backgrounds devoted more neural real estate to those regions," she said.
Stanford University psychologist Anne Fernald has found that the language gap can be measured as early as 18 months. By a child's second birthday that gap is already six months wide.
Fernald and her colleagues made recordings of what a group of low-income, Spanish-speaking children heard all day.
They found that infants didn't gain much from simply overhearing their parents and caregivers talk - the real learning came from being spoken to directly.
