Early Television Viewing Is Associated With Protesting Turning Off the Television at Age 6

Dimitri A. Christakis, MD, MPH; Frederick J. Zimmerman, PhD

Disclosures

Medscape General Medicine. 2006;8(2):63 

In This Article

Methods

Data for this study were drawn from the National Longitudinal Survey of Youth 1979 Children and Young Adults (NLSY-Child), an outgrowth of the original National Longitudinal Survey of Youth 1979 (NLSY79). The NLSY79, sponsored by the US Department of Labor, began with a nationally representative sample of almost 12,700 individuals aged 14-22 years in 1979 who have been interviewed annually or biennially since.[20] Blacks and Latinos were oversampled to provide statistical power for analyses involving these important subgroups, and population weights were used to draw valid national inferences. The NLSY-Child, begun in 1986 and conducted biennially, is an extensive collection of information for over 11,000 children of the female respondents to the NLSY79 in regard to developmental assessment, family background, home environment, and health history.[20] Information for the NLSY-Child is obtained from both the mother and child, depending on the child's age. The records from NLSY79 and NLSY-Child are linkable via the mother's sample identification number. Data from both the 1986-2000 NLSY-Child and NLSY79 were pulled for this study with the CHRR Database Investigator Software (Center for Human Resource Research, The Ohio State University, Columbus, Ohio, Build 1.4.1.57).

Our sample consisted of children who were approximately 6 years of age (66-89 months) in 1 of the 4 most recent survey waves: 1994, 1996, 1998, or 2000.

As part of the annual survey administered participants in the NLSY, parents were asked how often their children turn off the TV without protest when asked to do so by the parents. The Likert answers included "almost always," "more than half the time," "about half the time," "less than half the time," and "almost never." This question is asked of mothers of all children ages 4-6 years old.

Our main prediction variable was the mean number of hours of TV watched per day under the age of 4. As of 1990, mothers were asked the number of hours of TV that their children watch on a typical weekday and on a typical weekend day. When a response indicated no TV in the home, TV viewing hours were set to 0; when a response indicated more than 16 hours of viewing per day, the viewing was capped at 16 hours. The number of hours per week was computed as 5 times the number of hours watched during a typical weekday plus 2 times the number of hours watched on a typical weekend day. To get a daily average, we then divided this number by 7. The TV-exposure variable was then calculated as the reported TV time averaged over the 3 survey waves subsequent to age 6 months for each child. The age of the children in their first wave ranged from 6 to 30 months and averaged 19 months; at the second wave ages ranged from 18 to 42 months and averaged 29 months; at the third wave, ages ranged from 30 to 54 months and averaged 43 months.

Model covariates included the child's sex, race/ethnicity (Hispanic, black, or non-Hispanic/nonblack), measures of cognitive stimulation and emotional support in the home environment under the age of 5, the birth order of the child, maternal age at the birth of the child (in years), maternal education, the amount of TV watched at age 6, and calendar year at the survey wave in which the child was approximately age 6. Finally, to attempt to control for the possibility that TV protest before age 4 was associated with increased viewing at younger ages as well as at age 6, we included TV protest at age 4 (the youngest age for which that data was available).

Measures of cognitive stimulation and environmental support in the household were derived from items on the maternal supplement on the basis of the Home Observation for Measurement of the Environment-Short Form (HOME-SF).[21] Although the specific survey items differ for 0-2 year olds and 3-5 year olds, the cognitive stimulation score generally includes items that are related to outings, reading, playing, and parental role in teaching a child. For the youngest children, the emotional support score is composed of elements that are related to eating meals with both parents, parents talking to the child while working, and spanking (reverse-scored). For the 3-5 year olds, the emotional support score also includes items that are related to a child's choice in food decisions, and methods of dealing with a child who hits a parent.

It is also possible that TV protest at age 6 is associated with general behavioral problems at age 6, and that some unobserved variables (such as genetic endowment) cause both TV viewing and behavioral problems -- including TV protest -- at age 6. To control for such potential residual confounding, we included the Behavioral Problems Index (BPI) externalizing scale score at age 6, a validated measure of childhood behavior problems that is based on the Child Behavior Checklist that has been used in previous studies.[22,23,24] This 20-item scale includes questions, such as whether the child cheats, bullies, has trouble getting along with peers, and so forth. Including among the items are those asking whether the child is disobedient at home, argues too much, and is excessively stubborn. The full scale is standardized to national norms that are specific to age and sex. Inclusion of this scale is intended to ensure that any observed effect of the predictors on the outcome is specific to an inclination to protest the TV being turned off, and is not confounded by a difficult personality in general.

Finally, to control for the possibility that behavioral problems in early life led to increased TV viewing then and to increased likelihood of TV protest at age 6, we also included the BPI externalizing variable assessed at age 4 (ages 48-54 months) as a covariate in a subanalysis. Unfortunately, the BPI externalizing score for this age group was not collected in all years and was therefore only available for a subset of children, significantly limiting the overall sample. We therefore present these findings as a subanalysis only.

To simplify the interpretation of the coefficients in our regression model, we normalized BPI externalizing, cognitive stimulation, and emotional support by dividing each value by its standard deviation. Accordingly, a 1-unit change in each of these variables represents a change of 1 SD for our sample.

Children with any of the following 5 health conditions were excluded: serious hearing difficulty or deafness, serious difficulty in seeing or blindness, serious emotional disturbance, mental retardation, or crippled/orthopaedic handicap.

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