It may be fading altogether from the fabric of chaotic family life but the background noise from an unattended TV continues to be heavily implicated among environmental risks to children's learning development, say researchers at the University of Massachusetts.

And were television viewing behavior not changing so fast, the warning might be put about that half-watched reruns of Frasier, Friends or The Cosby Show were likely to do more long-term damage than a steady diet of children's programs.

In setting up its laboratory investigation of family viewing behavior, the Massachusetts team led by Heather Kirkorian took into account a finding from 2006 that over a third of children in the US lived in houses where the TV was on most or all of the time.

They were also interested to test evidence from 2001 that a substantial slice of young children's solitary toy play and play with parents happened in the presence of television. When it did and when parents were distracted, it was typified by shorter play episodes, less focused attention – less useful communication.

The Amherst team set up an elaborate, theatrical experiment in which the interactions between 51 12-, 24- and 36-month old children and a parent were observed – half an hour with the TV on, half an hour without, the order selected at random.

A playroom was built inside their laboratory, furnished with an armchair, a table with magazines and newspapers, an open-shelved toy chest, a TV, video player. Next to it, on the other side of a one-way mirror, the experimenter managed the TV and video controls and studied camera views of the subjects.

As well as old comedy series, shows chosen for appropriate background noise included home repair, daytime reality and cookery.

Unremarkably, it emerged that younger children tended to be groomed more by their parents; there was more “object play” with older children. Active involvement decreased over the course of the hour, whether or not the TV was on. Parents were generally less responsive when it was on.

The children, on the other hand, were not affected by the television noise. Older children were generally more responsive, but no more so than was developmentally appropriate for their age.

The researchers concluded that television did indeed inhibit the interaction between parents and children but almost entirely because parents were distracted by what they saw and heard.

Kirkorian and her colleagues write in Child Development that preliminary analysis of the results from another project suggest that overall quality of parent-child interaction also decreases in the presence of a children’s television programs – but with the compensation that co-viewing is often the basis for “scaffolding” behavior on the part of parents (for example singing along or asking questions), which predicts the quality of their children’s attention.

They recommend more observation exercises in more genuine family surroundings, to control for the possibility that parents were extraordinarily attentive to their children while under observation in the novel laboratory setting.

See: Kirkorian H L, Pempek T A, Murphy L A, Schmidt M E and Anderson D A, “The Impact of Background: Television on Parent-Child Interaction” Child Development Sept/Oct 2009, 80, 5 pp 1350-1359