Many parents also express satisfaction with the educational benefits of TV and how it can teach positive behaviours.

According to the study, in a typical day more than eight in 10 (83 per cent) children under the age of six use screen media, with those children averaging about two hours a day. Media use increases with age, from 61 per cent of babies one year or younger who watch screen media in a typical day (for an average of 1:20) to 90 per cent of four to six year-olds (for an average of 2:03).

The report, "The Media Family: Electronic Media in the Lives of Infants, Toddlers, Preschoolers, and Their Parents," is based on a survey of 1,051 parents with children age six months to six years old and a series of focus groups across the country.

In many homes, parents have created an environment where the TV is a nearly constant presence, from the living room to the dining room and the bedroom. One in three (33 per cent) children this age has a TV in their bedroom (19 per cent of children ages one year or younger, 29 per cent of children ages two-three years, and 43 per cent of those ages four-six years).

The most common reasons parents give for putting a TV in their child‘s bedroom is to free up other TVs in the house so the parent or other family members can watch their own shows (55 per cent), to keep the child occupied so the parent can do things around the house (39 per cent), to help the child fall asleep (30 per cent), and as a reward for good behaviour (26 per cent).

As one mother who participated in a focus group in Irvine, CA said, "Media makes life easier. We‘re all happier. He isn‘t throwing tantrums. I can get some work done."

A third (32 per cent) of children this age live in homes where the television is on all (13 per cent) or most (19 per cent) of the time and a similar proportion (30 per cent) live in homes where the TV is on during meals all (16 per cent) or most (14 per cent) of the time.

As a focus group mother from Columbus, OH explained, "The TV is on all the time. We have five TVs. At least three of those are usually on -- her bedroom, the living room and my bedroom."

Children whose parents have established these heavy TV environments spend more time watching than other children: for example, those who live in households where the TV is on all or most of the time spend an average of 25 minutes more per day watching TV (1:16 vs. 0:51), and those with a TV in their bedroom spend an average of 30 minutes more per day watching (1:19 vs. 0:49).

"Parents have a tough job, and they rely on TV in particular to help make their lives more manageable. Parents use media to help them keep their kids occupied, calm them down, avoid family squabbles and teach their kids the things parents are afraid they don‘t have time to teach themselves," said Kaiser vice president and director program for the study of entertainment media and health Vicky Rideout.

At a time when there is great debate on the merits of educational media for children, many parents are enthusiastic about its use. For example, two-thirds of parents (66 per cent) say their child imitates positive behavior from TV, such as sharing or helping. A large majority of parents (69 per cent) say computers mostly help children‘s learning and a plurality (38 per cent) say the same about watching TV (vs. 31 per cent who say TV "mostly hurts" and 22 per cent who say it doesn‘t have much affect either way).

The study found that how parents feel about TV‘s benefits is related to how much time children spend watching. Children whose parents say TV mostly helps learning spend an average of 27 minutes more per day watching than children whose parents think TV mostly hurts.

In focus groups, parents noted many specific benefits of TV viewing for their children, such as spurring imaginative play, teaching letters and words and learning a foreign language. One mother noted, "Out of the blue one day my son counted to five in Spanish. I knew immediately that he got that from Dora."

Another mom said, "My daughter knows her letters from Sesame Street. I haven‘t had to work with her on them at all."

Since a similar survey in 2003, there have been increases in the share of children in households with at least one computer (from 73 per cent to 78 per cent), with internet access (from 63 per cent to 69 per cent), and with high-speed internet access (from 20 per cent to 42 per cent).

There was a small but statistically significant decrease in the per cent of children living in households where the television is kept on always or most of the time, from 37 per cent in 2003 to 32 per cent in 2005, and of children living in households where the television is on during meals always or most of the time, from 35 per cent in 2003 to 30 per cent in 2005.

The study also found that among children who do each activity in a typical day, children are spending an average of 17 minutes less per day listening to music and 10 minutes less per day watching TV.