To develop causal hypotheses regarding the effects of television viewing on cognitive processes in children and to examine the proposition that deleterious effects of television may be stronger among children with attention-deficit/hyperactivity disorder.
Longitudinal study involving 2 phases occurring 18 months apart.
University research facilities in Lexington.
Fifty-nine children with attention-deficit/hyperactivity disorder and 106 comparison children. The children's mean age was 7.18 years at phase 1 and 8.74 years at phase 2.
Main Outcome Measures
Laboratory measures of visual attention to television, cognitive engagement to televised stories, factual recall of televised stories, and causal recall of televised stories. Parental reports of a child's weekly television viewing.
Among comparison children, phase 1 television viewing negatively predicted phase 2 visual attention and phase 2 cognitive engagement (after accounting for phase 1 levels of the outcome variables and any relevant demographic variables). Also among comparison children, phase 1 attention negatively predicted phase 2 television viewing, even after accounting for phase 1 levels of television viewing and relevant demographic variables. These patterns were not observed among children with attention-deficit/hyperactivity disorder.
Contrary to recent arguments, television viewing was associated with cognitive abilities in comparison children but not children with attention-deficit/hyperactivity disorder, a finding that suggests more careful examinations of the relation between television viewing and children's cognitive abilities are in order. Future studies should consider the possibility that any effects of television may be limited to certain developmental periods.
The average US child spends almost 27 hours per week watching television, a figure that has remained constant over the past 5 years.1 Not surprisingly, the potential effects of television on children's cognitive abilities have received much attention in popular and professional discourse.2- 4 Commentary on this issue ranges from omnibus indictments of television as a deleterious influence on children's cognitive development2 to encouraging endorsements of the current television landscape as supportive of increased cognitive complexity and improved problem solving.3 Unfortunately, much of this commentary does not rise above speculation because little research has actually examined the effects of media exposure on children's cognitive abilities.4
Among the emerging research in this area, a handful of studies have examined the relation between television viewing and processes such as attention and comprehension. Findings suggest that television viewing is negatively correlated with later performance in both of these areas,5,6 and have led some scholars to speculate that television viewing may play an exacerbating, if not causal, role in the development of attention-deficit/hyperactivity disorder (ADHD).6 This hypothesis is consistent with evidence indicating that children with ADHD watch more television than their peers7 and experience significant impairments in comprehending stories, a crucial skill in achieving academic success.8
There is some debate surrounding the suggestion that the existing correlational evidence supports the contention that television has deleterious effects on children's cognitive abilities.9,10 Some scholars9 have argued that because individual variation in attentional styles is evident even during infancy, this evidence could also be given the interpretation that children with a predisposition for attention problems are more likely to watch television at an early age. In response to this argument, it has been suggested that the negative effects of television viewing on cognitive processes may be particularly salient in children predisposed for ADHD.10 Accordingly, research is needed that helps clarify the causal direction of the relations between television viewing and cognitive abilities and addresses the issue of whether, as recently suggested, these differ in children with ADHD and comparison children.
Lorch and colleagues8,11 have used a television viewing method to understand the attention and story comprehension abilities of children with ADHD and comparison children. In this approach, children watch 2 television programs, 1 in the presence of toys and 1 in the absence of toys. Visual attention to the television is recorded throughout each program. At the end of each program, children are asked questions assessing their recall of specific factual information (ie, “what” questions assessing a child's understanding and recall of specific factual information from the show) and causal relations (ie, “why” questions assessing a child's ability to link earlier information in the story with later information to understand why an event occurred). The television viewing method has the advantage of directly assessing the cognitive processes involved in story comprehension, and is especially appropriate for research involving children with ADHD because it does not involve reading, a skill in which children with ADHD are frequently impaired.12
The results of studies using this method consistently reveal that in the absence of toys there are no significant differences in visual attention or story recall between children with ADHD and comparison children. However, when toys are present, children with ADHD show a steeper decrease in visual attention than do comparison children, and exhibit significantly poorer performance on questions testing causal relations.8 In addition, the amount of time that children spend in long looks at the television (ie, ≥15 seconds) accounts for the recall differences between children with ADHD and comparison children.8,11 This finding is important because long looks are considered an overt indicator of deeper cognitive processing.13
While the television viewing method has allowed for an increased understanding of the manner in which the attention problems of children with ADHD may impact their story comprehension, to our knowledge, no research has used data gathered using this approach to examine the relation between television viewing and cognitive abilities in a longitudinal study. Accordingly, the present study uses longitudinal data that include variables obtained through the use of the television viewing method to develop more careful hypotheses about the causal relation between television viewing and cognitive processing, and to examine whether—as suggested by other researchers10—this relation differs between children with ADHD and comparison children.
Data for this study were provided by 165 children participating in a longitudinal research project, approved by the University of Kentucky institutional review board, examining the comprehension of televised stories in children with ADHD and a comparison sample. Participants with ADHD (n = 59) were recruited from clinical settings. Comparison children (n = 106) were recruited through newspaper advertisements. Before their children's enrollment in this study, parents provided written informed consent and completed a semistructured interview and several standardized assessment instruments to verify their children's diagnostic status. Children accepted into the ADHD group averaged more than 12.24 symptoms of ADHD (SD, 3.44 symptoms). Children accepted into the comparison sample averaged less than 1 symptom of ADHD (SD, 0.72 symptoms). Data were collected in 2 phases spaced approximately 18 months apart, with children being a mean age of 7.18 years (SD, 1.71 years) at phase 1 and 8.74 years (SD, 1.76 years) at phase 2.
During each of the phases, children visited university research facilities to complete several experimental tasks related to story processing, including those used in this study and described later. While the children completed these tasks, surveys and standardized questionnaires regarding their behavior, social environment, media use, and media environment were completed by their parents.
Parents were asked to report the number of hours that their children spent watching television, excluding VCR use, during specific periods on weekdays (eg, “Monday through Thursday, 6 AM–noon”) and during these same periods on each specific weekend days (eg, “Friday, 6:00 AM–noon”). Collectively, these periods spanned the entire week. Parent reports were then combined to form a total weekly television viewing composite. Existing evidence suggests that data gathered using this approach to the assessment of television viewing approximate actual behavior better than global questions focused on estimates of daily or weekly television viewing.14
The television viewing method was used to assess children's comprehension of and attention to televised stories. Because the toys present condition most closely simulates the home viewing environment and allows for the assessment of children's allocation of attention to the programs vs the toys, only data from this viewing condition are included in the present study. During the 2 phases of the study, the children viewed different episodes of the cartoon show, Rugrats. This show was chosen because it appeals to children across a wide age range and maintains a strong narrative structure that facilitates story comprehension assessment. The children were videotaped while the program was presented, and the videotapes were later coded for moment-to-moment visual attention. After the program was finished, all children viewing a given program were asked the same series of questions involving factual and causal information. Four variables obtained during each of the 2 phases are included in the present study: (1) attention, operationalized as the total percentage of time that a child's gaze was fixed on the television screen; (2) cognitive engagement, operationalized as the total amount of time that a child spent in looks at the television lasting 15 or more seconds; (3) factual recall, operationalized as the percentage of factual questions a child answered correctly; and (4) causal recall, operationalized as the percentage of causal questions a child answered correctly.
Means and SDs for all variables included in this study are presented separately by diagnostic group in Table 1, along with 1-way analysis of variance results. For demographic variables, there were no differences between groups in the mean age across both data collection times; however, children with ADHD were significantly more likely to be male and had mothers who reported significantly fewer years of education. For the principal variables of interest in this study, the children with ADHD were described by their parents as watching significantly more weekly television than the comparison children at both phases, and performed more poorly on laboratory tasks assessing visual attention, cognitive engagement, and recall of causal information at both phases of the study. Children with ADHD also performed more poorly than comparison children on factual recall at phase 2 but not phase 1.
The correlations among all variables examined in this study are reported in Table 2. Correlations calculated from data provided by children with ADHD are reported above the diagonal line formed by the NA (not applicable) results, and correlations calculated from data provided by comparison children are reported below this diagonal line. As can be observed, among comparison children, most longitudinal correlations between television viewing and laboratory measures collected at a different phase were significant, suggesting the possibility of bidirectional causal effects. By comparison, these correlations were not significant and most approached 0 among children with ADHD, suggesting the possibility that the relations between television viewing and the laboratory measures differ in children with ADHD and comparison children.
Fisher r-to-z comparisons were used to test the differences between samples in the longitudinal relation between television viewing and laboratory measures. There were significant (2-tailed) differences between diagnostic groups in the correlations between phase 1 television viewing and phase 2 attention (z = 2.16, P = .03), between phase 1 television viewing and phase 2 cognitive engagement (z = 2.22, P = .03), and between phase 1 television viewing and phase 2 factual recall (z = 1.80, P = .07). In each case, the correlation obtained in the comparison group was significantly greater than that obtained in the ADHD sample. No other group differences in correlations were significant.
Cross-lagged hierarchical regression analyses were then conducted to develop causal hypotheses about significant longitudinal correlations involving television viewing and the laboratory measures obtained through the television viewing method. Cross-lagged comparisons estimate the linear relation between a predictor variable measured at an early point (eg, phase 1 television viewing) and a criterion variable measured at a later point (eg, phase 2 attention to television) after accounting for levels of the criterion variable at the time the predictor variable was assessed (eg, phase 1 attention to television).15 Although not a definitive demonstration of causality, the identification of a significant relation between the predictor and criterion variables using this approach provides stronger evidence for a possible causal mechanism than other correlational approaches.16 Where indicated by significantly different correlations (ie, phase 1 television viewing to phase 2 cognitive engagement, phase 2 attention, and phase 2 factual recall), separate analyses were calculated in each diagnostic group. Because the sex distribution and the amount of education received by the mother differed between diagnostic groups, these predictors were statistically controlled for whenever they evinced a significant correlation with an outcome to avoid confounding the effects of these predictors with those of diagnostic status.
As summarized in Table 3, among comparison children, phase 1 television viewing negatively predicted phase 2 attention, even after accounting for a participant's age and phase 1 attention. This effect was not observed among children with ADHD (Table 3).
As summarized in Table 3, among comparison children, phase 1 television viewing negatively predicted phase 2 cognitive engagement, even after accounting for phase 1 cognitive engagement. The significant effect of phase 1 television viewing on phase 2 cognitive engagement was not observed among children with ADHD (Table 3).
As summarized in Table 3, phase 1 television viewing did not predict phase 2 factual recall after accounting for the effects of phase 1 factual recall in either sample of children. As suggested by the r-to-z comparisons previously described, the effect of phase 1 television viewing on phase 2 causal recall was examined in a sample including all children regardless of diagnostic status. These results are summarized in Table 4. As can be observed, phase 1 television viewing did not predict phase 2 causal recall after accounting for the effects of phase 1 causal recall and mother's education.
Analyses examining the relation between phase 2 television viewing and phase 1 performance on laboratory measures of attention, cognitive engagement, factual recall, and causal recall (after accounting for phase 1 amounts of television viewing and the effects of significant covariates) are summarized in Table 5. As can be observed, among phase 1 laboratory measures, only phase 1 visual attention acted as a significant (negative) predictor of phase 2 television viewing. Post hoc analyses, reported in Table 3, suggest that the effect of phase 1 attention on phase 2 television viewing may be limited to comparison children.
This study sought to further develop causal hypotheses about the relation between television viewing and 2 important cognitive abilities: attention and comprehension. An additional goal was to examine the recent proposition that these relations may differ between children with ADHD and comparison children. Results suggest that, among comparison children, increased levels of television viewing at phase 1 were associated with decreased performance on phase 2 measures of visual attention and cognitive engagement, a finding that is consistent with previous literature in this area.5,6 However, the relation between television viewing and visual attention among comparison children seems to have a bidirectional component because reduced performance on phase 1 visual attention measures was associated with increased television viewing at phase 2. This last finding is consistent with arguments suggesting that children who have difficulty paying attention may favor television and other electronic media to a greater extent than the media environment of children without attention problems.9 More important, contrary to recent suggestions that any deleterious longitudinal relation between television and cognitive outcomes may be more salient among children with ADHD,10 no effects of television viewing were observed among children with this diagnosis. Indeed, Fisher r-to-z comparisons indicated that the longitudinal relations between television viewing and laboratory measures of attention, cognitive engagement, and factual recall were in fact smaller in children with ADHD than in comparison children. Findings are of particular interest because they are based on an approach that directly assesses the cognitive processes that are hypothesized to affect story comprehension rather than rely on parent or child reports of symptoms or imputations about cognitive performance based on standardized achievement tests.
One possible explanation for the finding that television viewing may have an effect on attention and cognitive engagement only among comparison children is that the cognitive processing deficits associated with ADHD are so strongly rooted in biological predisposition that, among children with this diagnosis, environmental characteristics such as television viewing have a negligible effect on these cognitive processing areas.9 Alternatively, characteristics of the current sample may limit the ability of this study to identify any effects of television viewing among children with ADHD. For instance, the effects of television viewing on attention and cognitive engagement may occur at younger ages and, thus, have taken hold by the time children are of elementary school age. Another possibility is that, among children with ADHD in the age group being considered in this study, a longer period is required to observe effects of television viewing on the cognitive processes being measured in the laboratory. While this alternative would still run counter to the speculation that the effects of television are strongest among children with ADHD, it does allow for the possibility of added environmental contributions to the cognitive deficits exhibited by these children. Finally, it is possible that the direct laboratory assessment of visual attention used in this study examines a different spectrum of attentional abilities than those assessed by the rating forms or clinical impressions used in other studies and, therefore, influences the results.
Contrary to prior literature in this area,5 current results showed no effect of television viewing on subsequent story comprehension in either group. The same developmental and measurement considerations as discussed previously may apply to this finding. In addition, it should be considered that in the present study, comprehension was assessed via recall of televised content. It may be the case that television exposure may affect comprehension of information presented through other media (eg, orally or in print), but not televised content.
A first limitation that should be considered when evaluating this study's findings is associated with the cross-lagged approach used. As stated previously, results obtained from this approach provide stronger evidence for a possible causal mechanism than other correlational approaches, but are not a definitive demonstration of causality. As discussed previously, findings also are limited by the age range of the children sampled. The possibility that findings are influenced by the television viewing method being used has already been discussed in this paper. An additional methodological limitation involves the use of a weekly composite of television viewing to assess television viewing, an approach that fails to capture possible differences associated with the content of the programming viewed by children. Existing research17 using comparison samples suggests that educational and prosocial programming can foster the development of academic and social skills in children. As such, current results can only be generalized to quantitative increments in television viewing, but leave open the possibility that different types of programming content can differentially affect children's cognitive abilities. Finally, particularly among children with ADHD, current sample sizes may have prevented the identification of additional effects. For instance, it was noted earlier that many of the longitudinal correlations involving weekly television viewing and laboratory measures obtained through the television viewing method seemed to have greater magnitude among comparison children than children with ADHD; however, in the present study, not all of these diagnostic group differences were significant. Research involving larger samples of children with ADHD could be more sensitive to smaller effect sizes.
Overall, the pattern of results obtained in the present study suggests that by elementary school age, television viewing may have an effect on the attention and cognitive engagement abilities of comparison children but not of those children with ADHD. While limited to the age group under study, this finding contradicts recent speculation that children with ADHD may be most at risk for any deleterious effects of television viewing10 and raises the interesting possibility that, at certain developmental periods, it may be comparison children who are most at risk for these effects. Certainly, future research should continue to examine this question using approaches that overcome the limitations of the present study. Studies contrasting children with ADHD and comparison children at younger ages, and research using children of the same age sampled in the present study but allowing for greater time for any effects of television viewing on children with ADHD to take place, seem particularly indicated. Television and ADHD are inexorable realities of the current developmental landscape facing children in the United States; it is to these children's benefit that scholarly discussion about the possible relation between television and attention problems move away from speculation and toward an empirically informed understanding.
Correspondence: Ignacio David Acevedo-Polakovich, MS, Department of Psychology, University of Kentucky, Lexington, KY 40506-0044 (Acevedo@uky.edu).
Accepted for Publication: December 21, 2005.
Funding/Support: This study was supported by grant MH47386 from the National Institute of Mental Health, Bethesda, Md; and by National Institutes of Health National Research Service Award DA07304 from the National Institute on Drug Abuse, Bethesda.
Role of the Sponsor: The funding bodies had no role in data extraction and analyses, in the writing of the manuscript, or in the decision to submit the manuscript for publication.
Acknowledgment: We thank the 2 anonymous reviewers for their helpful comments, which vastly improved the direction and presentation of this article.
Ignacio David Acevedo-Polakovich, Elizabeth Pugzles Lorch, Richard Milich, Rebecca D. Ashby. Disentangling the Relation Between Television Viewing and Cognitive Processes in Children With Attention-Deficit/Hyperactivity Disorder and Comparison Children. Arch Pediatr Adolesc Med. 2006;160(4):354–360. doi:10.1001/archpedi.160.4.354