Language development.

The language we share – and how we share it – makes more of an impact than most parents realize.

Some of the most important research that has ever been conducted in the area of early intellectual development comes from studies of children’s early language environments. Large-scale studies that have been repeated many times since the late 1960s consistently demonstrate that the number of words with a kind tone that we direct toward our children is strongly correlated or linked with their intellectual development over time. Conversely, language shared in sharp, harsh tones does not make a positive impact on children’s intellectual development.

…conclusion:

To jump-start early learning, talk to your child often and use a kind tone of voice. Describe the world around you. Point out interesting objects, colors, and events. Language in appears to equal intelligence out.