The AAP has the following very clear position on kids/babies and television (and all screen media, including computers):
“Children of all ages are constantly learning new things. The first 2 years of life are especially important in the growth and development of your child's brain. During this time, children need good, positive interaction with other children and adults. Too much television can negatively affect early brain development. This is especially true at younger ages, when learning to talk and play with others is so important.
Until more research is done about the effects of TV on very young children, the American Academy of Pediatrics (AAP) does not recommend television for children age 2 or younger. For older children, the Academy recommends no more than 1 to 2 hours per day of educational, nonviolent programs."
"As previously recommended by the AAP, babies or toddlers younger than 2 years should avoid all screen media." (AAP Advocates for Safer Media & Music)