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Role of Media in Childhood Obesity

Student Paper

Submitted to
Mass Communication Theory & Methodology Division
AEJMC 2005 Convention
August 10-13, San Antonio, Texas



The role of media in childhood obesity:
A look from mass communication perspectives
Ying Du

Ph.D. Student, UNC-CH University Fellow
School of Journalism and Mass Communication
University of North Carolina at Chapel Hill
Campus Box 3365
Chapel Hill, NC 27599
(919) 843.5857
[log in to unmask]
Abstract
Recent years have witnessed the rapid increase in obesity among 
American children. Obesity research has been done mostly by scholars 
in health-related fields. Although there is a wealth of studies 
regarding the role of media in childhood obesity, most of them 
address only one or two aspects of the relationships and none has 
given a panorama to the issues. Moreover, few studies are guided by 
media effects theories. This paper explicates key concepts related to 
childhood obesity, synthesizes the existing literature in the area, 
and links media effect theories to the research findings for 
explanation and prediction purposes. It attempts to serve as a brief 
but comprehensive map for new explorers from mass communication perspectives.
The role of media in childhood obesity:
A look from mass communication perspectives
Introduction
Recent years have witnessed the rapid increase in obesity among 
American children. According to the U.S. Centers for Disease Control 
and Prevention (CDC), since 1980 the proportion of overweight 
children aged 6-11 has more than doubled, and the rate for 
adolescents (ages 12-19) has tripled (CDC, 2004a, online).  The 
rising rates of childhood obesity pose a significant public health 
challenge for us. While there are many causes of the problem, 
children's media use and media effects on children are important 
pieces of the puzzle – during the same period in which childhood 
obesity has increased so drastically, there has been an explosion in 
media targeted to children: TV shows and advertisement, specialized 
cable networks, video games, and internet Websites. Along with this 
media explosion, children spend more and more time with media and 
logic suggests that, the more media exposure, the greater effect on children.
Obesity research has been done mostly by scholars in health-related 
fields. Although there is a wealth of studies regarding the role of 
media in childhood obesity, most of them address only one or two 
aspects of the relationships and none has given a panorama to the 
issues. Moreover, few studies are guided by media effects theories. 
As the role of media in childhood obesity has aroused increasing 
concerns, more and more mass media researchers have taken part in 
childhood obesity research, although it is relatively a new ground 
for them. By explicating key concepts, synthesizing the existing 
literature in the area, and linking media effects theories to the 
research findings for explanation and prediction purposes, this study 
attempts to serve as a brief but comprehensive map for new explorers 
from mass communication perspectives.
Defining Childhood Obesity

	Although a variety of definitions of childhood obesity are in use, 
and no commonly accepted standard has yet emerged, the body mass 
index (BMI) is most widely used to indicate obesity, as it is the 
tool recommended by U.S. Centers for Disease Control and Prevention 
to screen for overweightness in children (CDC, 2004a, online). BMI is 
calculated as weight in kilograms divided by the square of height in 
meters (kg/m2). Since children's body fatness changes over the years 
as they grow (see Figure on left for example, source from CDC, 2004b, 
online), and girls and boys differ in their body fatness as they 
mature, BMI for children must be age and gender specific and is 
referred to as "BMI-for-age", which is plotted on gender specific 
growth charts released by CDC (CDC, 2004b, online). The CDC 
classifies children as "overweight" or "obese" if they are above the 
95% percentile for their age and gender, and "at risk of being 
overweight" or "at risk of obesity" if they are between the 85% and 
95% percentile. Children who have from the 5th up to the 85th 
percentile are considered having an acceptable weight (see Table 1).
Table 1
Obesity Status
BMI-for-age
Underweight
< 5th percentile
At risk of obesity
85th – 95th percentile
Obese
 > 95th percentile

BMI is used widely because of the relative ease and accuracy of the 
basic measurements. Besides BMI, other measurements, such as skinfold 
thickness, and percentage body fat, have been used as dependent 
variables to assess childhood obesity. Percentage body fat is 
considered an ideal measurement for obesity but is impractical to 
measure, as it is less easy to obtain (Cole, Bellizzi, Flegal, & 
Dietz, 2000).  It can be estimated from densitometry or from total 
body water converted to fat-free mass (FFM). For boys, risk of 
overweight is usually defined as _20%Fat and the presence of 
overweight is defined as _25%Fat; for girls, the cutoff for risk of 
overweight is _25%Fat and that for presence of overweight is _30%Fat 
(Malina & Katzmarzyk, 1999). As for skinfold thickness, some 
researchers maintain that it is more sensitive and reliable in 
measuring obesity than BMI, and obesity should be defined as a tricep 
skinfold equal to or greater than the 85th percentile, and 
superobesity defined as a tricepts skinfold equal to or greater than 
the 95th percentile for children or adolescents of the same age and 
gender (Dietz and Gortmaker, 1985).
In an attempt to evaluate the validity of BMI as an indicator of the 
risk and presence of childhood obesity, Malina and Katzmarzyk (1999) 
applied the aforementioned reference and cutoff values to several 
ethnically diverse samples, with use of triceps skinfold thickness 
and estimated percentage body fat as the criteria for obesity, 
finding that BMI has high specificity, high efficiency, but low and 
variable sensitivity. "Allowing for the ease of measuring height and 
weight in the field setting, the BMI is an acceptable and valid 
indicator of the risk of overweight and the presence of overweight in 
adolescents" (p. 136S).
National BMI reference data are now available in many countries, and 
the definitions of "at risk of obesity" (BMI _ 85%) and "obesity" 
(BMI _ 95%) are widely used and recommended. In recent years, some 
scholars have attempted to achieve a uniform international reference 
data system for international comparison. It seems, however, the rush 
to use a universal definition of childhood obesity is premature and 
impractical (Reilly, 2002). By now, those countries that do not have 
their own national BMI reference data usually use U.S. CDC standard 
for reference, as it is recommended by the World Health Organization 
for international comparison.

The Role of (Mass) Media
	The role of media is not a monolithic concept. Instead, several 
decades of media research and literature have made it a composite 
concept consisting of several dimensions, including type of media, 
media use, media content, media influence, and the cause-effect 
process. The role of media has been a central concept in the 
empirical school of mass communication research ever since the early 
days of the field. Much of the inquiry has been focused on whether 
the media have any effect, how much effect, which medium (e.g., 
newspaper or television) has effect on what aspect (e.g., perception 
of reality) of the audience, or under what conditions or 
circumstances may the effect occur.
Media and Childhood Obesity
	The role of media in childhood obesity has drawn significant 
attention from researchers from a variety of disciplines, including 
medical sciences, public health, child development, advertising, and 
mass media.  Although the vast majority of the relevant literature 
comes from health-related fields, some attention has been given from 
a media perspective.  Pediatricians, child development experts, 
nutritionists, and media researchers have examined the role of media 
in childhood obesity in one or more of the following aspects: (a) 
What is the relationship between the amount of time children spend 
using media and childhood obesity? Can reducing children's media use 
time result in weight loss? (b) What is the relationship between 
children's media use and their physical activities? Does children's 
media use time displace their time spent on physical activities? (c) 
What is the effect of media on children's eating behaviors? To what 
extent are children influenced by food advertising to make food 
choices? What is the food content in food ads and non-ads media 
programs? Does unhealthy food prevail over healthy food?
Media use time and obesity
	A simple way to find out the role of media in childhood obesity 
would be to link obesity directly to the amount of time spent using 
media.  Such attempts have been included in most of the research on 
this topic.
A vanguard work,  study analyzed a large data set from a national 
survey of more than 13,000 American children, the National Health 
Examination Survey (NHES), finding a significant association between 
the amount of time children spent watching television and the 
prevalence of obesity: among children aged 12 to 17, the prevalence 
of obesity increased by 2% for each additional hour of television 
viewing, controlling for other variables such as race and 
socio-economic status.  Since then, several more large-scale national 
studies have also discovered such a correlation between media use and 
body weight.   use data from the 1988 to 1994 waves of the National 
Health and Nutrition Examination Surveys (NHANES) to explore the 
relationship between TV watching and obesity among boys and girls 
aged 8 to 16, finding that both boys and girls who watch 4 or more 
hours of TV have more body fat and greater body mass index (BMI) than 
those who watch less than 2 hours per day.  Another study using the 
1988-1994 NHANES data discovers that TV watching time is positively 
associated with obesity among girls .
	As cross-sectional studies, like the aforementioned, cannot reveal 
causal relationships, some researchers use longitudinal or 
experimental methods, which are commonly considered more appropriate 
ways to demonstrate cause and effect.   conducted a randomized 
controlled trial in which the amount of time a group of 3rd and 4th 
graders spent with TV, videos, and video games was reduced and the 
other group's was controlled.  The intervention involved a "turnoff" 
period of no screen time for 10 days, followed by limiting TV time to 
7 hours per week as well as learning selective viewing.  At the end 
of a 6-month curriculum, students who received the intervention 
achieved statistically significant reductions in their television 
viewing and meals eaten in front of a TV set, as well as decreases in 
BMI, triceps skinfold thickness, waist circumference, and 
waist-to-hip ratio.   longitudinal study is another example of an 
attempt to demonstrate a causal relationship.  In this study, 
preschoolers are enrolled and followed into early 
adolescence.  Findings suggest that TV watching is an independent 
predictor of the change in the child's BMI, and the researchers 
conclude that children who watch the most television during childhood 
have the greatest increase in body fat over time.
Media use and physical activity
	The role of media in childhood obesity can be complicated, and 
linking obesity directly to media use time may oversimplify the 
situations.  As common knowledge suggests that physical activity is 
closely associated with health, some researchers pay more attention 
to the relationship between children's media use and their physical 
activity habits.
	Based on a "zero-sum" assumption, it is logical to assume that an 
increase in time spent using media means a decrease in time spent on 
physical activities.  Contrary to such an assumption, however, most 
relevant research finds weak or no significant relationship between 
media use time and physical activity time. In other words, the time 
children spend using media does not necessarily displace their time 
spent in physical activities.  For instance, Anderson et al.'s (1998) 
large-scale NHANES study finds no relationship between TV viewing 
time and the number of bouts of vigorous physical activity. Another 
study of a small sample of preschool children conducted in Texas 
finds a weak relationship between TV viewing and physical activity .
Media effect, dietary habits, and nutrition conception
	The fact that most studies have not discovered a significant 
relationship between children's media use time and their physical 
activity (energy expenditure) time calls for deeper thoughts.  It 
appears that media use time only, as a predictor, cannot explain 
obesity in the sense that it displaces children's time spent on 
physical activity.  Since food (energy intake) is another primary 
contributor to health, researchers reason, based on media effect 
theories, that the food-related content in media that children are 
exposed to may be an important factor in obesity.
Since children, compared to adults, are assumed much more susceptible 
to media exposure, some researchers contend that food-related 
programming content and food advertising have a powerful effect on 
children's food choices and eating behaviors.   manipulated 
advertising shown to children aged 5 to 8 at a summer camp, with one 
group viewing ads for fruit and juice and the other for candy and 
Kool-Aid, finding that children's food choices are significantly 
affected by which ads they saw.  A more recent study finds that 
students in grades 7-12 who watch more TV than other students tend to 
frequently eat fast food .  Some researchers assert that food ads may 
also lead to children's misconceptions of the healthy versus 
unhealthy food.  A number of studies have supported such an 
assertion. For instance,  show a group of 4th  and 5th graders a 
series of paired food items and asked them to choose the healthier 
item from each pair, for example, corn flakes or frosted flakes. 
Findings indicate that children who watch more TV are more likely to 
choose the less healthy food choice as opposed to the healthy one.
	In summary, media may play an important role in childhood 
obesity.  First, the majority of relevant research finds a link 
between the amount of time children spend watching TV and their body 
weight or body mass index.  Secondly, because no significant 
displacement relationship has been found between children's media use 
and physical activity, it is reasonable to suspect that children's 
dietary habits, another primary factor leading to health, is affected 
by media. In fact, a considerable part of the relevant literature has 
answered such a question by finding that food-related content in 
media, both programming and commercials, has significant associations 
with children's food preferences, conceptions of healthy food, and 
their eating behaviors.

The Cultivation Role of Media
Children's media exposure typically begins with television. Most 
children start watching television before they learn to read. As 
children have fewer external sources for information about the 
reality, it is logical to presume that television viewing is highly 
related to children's conceptions about the world (Gerbner, Gross, 
Morgan, Signorielli, & Shanahan, 2002; Signorielli & Staples, 1997). 
In other words, in terms of dietary habits, media could powerfully 
affect children's conceptions of nutrition, food choices, and eating 
behaviors.
	Cultivation analysis represents a set of theoretical and 
methodological assumptions and procedures designed to assess the 
long-term contribution that television viewing makes to people's 
conceptions of social reality (Gerbner, Gross, Morgan, Signorielli, & 
Shanahan, 2002; Signorielli & Morgan, 1990). This theoretical 
orientation is concerned with the more general and pervasive 
consequences of cumulative exposure to cultural media such as 
television, rather than how individual messages, programs, or even 
genres of programs may produce immediate change in audience attitude 
and behaviors. Over the past decades, although the perspective and 
body of cultivation theory have been subject to criticism, the fact 
remains that cultivation studies continue to find a positive relation 
between watching more television and having conceptions about the 
world that reflect the images seen on television (Signorielli & Morgan, 1996).
The theory of cultivation states that television has become people's, 
and increasingly children's, most common and constant learning 
environment, because its centralized mass production and routine use 
of a coherent set of images and messages are produced and appeal to 
the entire population – its socially constructed version of reality 
bombards all classes, groups, and ages with the same perspectives 
(Signorielli & Morgan, 1996). Television has its ability to 
standardize, streamline, amplify, and share with virtually all 
members of society the common cultural norms, and therefore, is the 
"wholesale distributor of images that form the mainstream of our 
popular culture" (p. 114).
Media content is the core element in cultivation process. Cultivation 
analysis generally begins with identifying and assessing the most 
recurrent and stable patterns in television content. This stage is 
indispensable because hypotheses concerning television contribution 
to viewers' conceptions about social reality cannot be formulated 
without reliable information on the images and portrayals media 
present. Much cultivation research has provided empirical support for 
the assumption that there are many critical discrepancies between the 
real world and the "world as portrayed on television", in other 
words, the TV world is a distorted reflection of the real world. 
Although they often match dominant ideologies and values, the shape 
and profiles of the television world rarely match "objective reality" 
(Signorielli & Morgan, 1996, p.120). For example, an early 
cultivation study finds that television drama tends to "sharply 
under-represent older people," although those over 65 constitute a 
rapidly growing segment of the U.S. population (Gerbner, Gross, 
Morgan, Signorielli, & Shanahan, 2002, p. 51). One of the most 
examined aspects of television content in cultivation analysis is sex 
or gender role stereotyping. Many studies have found that women are 
underrepresented and that most television characters are extremely 
gender-typed (Signorielli & Morgan, 1996).
With certain media content patterns identified and assessed, 
cultivation theory then contends that those who spend more time 
"living" in the world of television are more likely to give the 
"television answer" – they see the "real world" in terms of the 
images, values, portrayals, and ideologies that emerge through the 
lens of television.  More specifically, cultivation analysis 
investigates whether the differences in the attitudes, beliefs, and 
actions of light and heavy viewers reflect difference in their 
viewing patterns and habits, independent of, or in interaction with 
the social, cultural, and personal factors that differentiate light 
and heavy viewers (Signorielli & Morgan, 1996; Gerbner, Gross, 
Morgan, Signorielli, & Shanahan, 2002). For example, studies have 
found considerable support for the proposition that heavy exposure to 
the world of television cultivates exaggerated perceptions of the 
number of people involved in violence in any given week, as well as 
numerous other inaccurate beliefs about crime and law enforcement 
(Gerbner, Gross, Morgan, Signorielli, & Shanahan, 2002). One example 
of this is the "mean world syndrome."  Researchers have found that 
long-term exposure to television, in which frequent violence is 
virtually inescapable, tends to cultivate the image of a relatively 
mean and dangerous world – responses of those heavier compared to 
lighter viewers suggest the conception of reality in which greater 
protection is needed, most people "cannot be trusted," and most 
people "just look out for themselves" (Gerbner, Gross, Morgan, 
Signorielli, & Shanahan, 2002, p.52). Some researchers also tested 
the hypothesis that television can affect reality perceptions because 
people simply forget that what they see on TV is not real (Mares, 
1996). Findings indicate that those who tended to confuse fiction 
programs for reality see the world as a meaner, more violent, and 
also are more likely to give "TV answers" to questions about social 
class estimates.
Mainstreaming and resonance are two of the "after-the-fact" processes 
that explain the cultivation effect of media. "Mainstreaming" means 
that heavy viewing may absorb or override differences in perspectives 
that ordinarily develop from other factors and influences (Gerbner, 
Gross, Morgan, Signorielli, & Shanahan, 2002). As a process, 
mainstreaming represents the theoretical elaboration and empirical 
verification of the assertion that television cultivates common 
perspectives (Signorielli & Morgan, 1996). "Resonance" means that the 
congruence of the television world and real-life circumstances may 
resonate and lead to significantly amplified cultivation patterns 
(Signorielli & Morgan, 1996). In other words, heavy television 
viewers who have experienced physical violence, for example, get a double dose.
In short, the theory of cultivation attempts to understand and 
explain the dynamics of media as a distinctive feature of the modern 
age. Designed mainly for television and focusing on its pervasive and 
recurrent patterns of representation, cultivation analysis examines, 
proves, and explains the enduring and common consequences of growing 
up and living with television, in other words, the cultivation of 
stable, resistant, and widely shared assumptions, images, and 
conceptions reflecting the institutional characteristics and 
interests of the medium itself and the larger society (Gerbner, 
Gross, Morgan, Signorielli, & Shanahan, 2002; Signorielli & Morgan, 
1990; Signorielli & Morgan, 1996).

The Cultivation Role of Media in Childhood obesity
Most Americans under 45 began watching television before they could 
read or probably even speak (Signorielli & Morgan, 1996). Children 
today spend an average of five and a half hours per day using media, 
the equivalent of a full time job, and more time than they spend 
doing anything else except for sleeping (Roberts & Foehr, 2004). 
According to the principles of cultivation theory, in terms of 
dietary habits, media could powerfully affect children's conceptions 
of nutrition, food choices, and eating behaviors.
Food-related media content
Media content is determinant in the cultivation effect. Previous 
research has found evidence that the food-related content in media is 
unbalanced and misleading. First, much research has found that the 
majority of commercials during children's programming promote foods 
with low nutritional value, including candy, soft drinks, sugared 
cereals, potato chips, and other high-salt, high-fat snacks. For 
example, as cited in Signorielli and Lears (1992), Gerbner, Gross, 
Morgan and Signorielli's (1981a) analysis of prime time and weekend 
daytime commercials finds that food adverting accounts for more than 
one quarter of such commercials; food-related activities occurred in 
over 40% of commercials; sweets, snacks, and junk foods make up 
nearly half of food commercials.
Another study assembles data from seven sites across the U.S. 
representing a diverse range of medium-to-large television markets, 
content analyzes the children programs in the seven sampled program 
sources, such ABC, CBS, and NBC . A significant difference was found 
in this study between the proportion of healthy food ads and the 
unhealthy proportion - snacks and drinks make up 18.4% of all ads, 
fast food ads make up 5.7%, whereas the healthy food category makes 
up only 2.8% .
Kotz and Story's (1994) study assesses the TV commercials in 
children's Saturday morning programming, finding that high-sugar 
cereals were the most advertised food product, and other highly 
advertised items include food rich in fat and sugars, most of which 
had low nutritional value. They conclude that, given the findings of 
this study, it is evident that food advertising aimed at children 
attempts to persuade children to adopt eating patterns contrary to 
the principles of national dietary recommendations.
Byrd-Bredbenner and Grasso (1999) studied the commercials in 
prime-time programs most often watched by 2- to 11-year-olds and 
found that 89% of food and beverage advertisements focused on taste, 
convenience, and low cost; only 10% of the ads used nutrition or 
health factors alone to sell the products. A later study of 
Byrd-Bredbenner and Grasso (2000) content analyzes and compares the 
advertisements broadcasted in 1992 and 1998 to create a description 
of the health information conveyed in top-rated, prime time network 
television advertisements, finding that the foods most intensely 
advertised tend to be the ones overconsumed relative to the Dietary 
Guidelines for Americans and other dietary recommendations; the 
intake of soft drinks, a heavily advertised food on television, tends 
to be inversely correlated with milk consumption, a food almost never 
advertised on television; intake of fruits and vegetables is lower 
than the recommended amounts.
  study analyzes the trend in television advertising targeted to 
children, and compares results to the historical perspective of the 
last quarter century. Based on the Food Guide Pyramid and USDA Child 
Nutrition criteria, they evaluate the advertising content of the 16 
videotaped hours of Saturday morning children's programming on 4 
network channels, finding that 63% of the 353 commercials analyzed 
are for food products and the overall nutritional quality of 
commercials remains poor, promoting a high-fat, low-fiber diet. The 
study concludes that children's television food advertising continues 
to send inappropriate nutrition messages, with no improvement noted 
in 25 years.
Misleading messages about food, however, are not only found in 
commercials. Paying attention to non-ad media programs, several 
studies compare the nutritional value of food servings in TV shows 
with the established recommended nutritional guidelines.  For 
instance, another analysis conducted by Gerbner, Gross, Morgan and 
Signorielli (1981b) finds that prime time nutrition portrayal was 
anything but balanced: in a week-long sample of prime time and 
weekend daytime children's programming broadcast, eating, drinking, 
or talking about food occurred about nine times per hour; grabbing a 
snack was virtually as frequent as breakfast.  study content analyzes 
the sampled top-ranked prime time shows, finding that food references 
occur almost 5 times per 30 minutes, 60% of which are for 
low-nutrient beverages such as coffee, soft drinks, and 
alcohol.  This study also finds that snacks make up 72% of the food 
references, the vast majority of which tend to be sweet and salty, in 
other words, unhealthy. A third finding of this study is that 
characters in the analyzed programs eat more between-meal snacks than 
regular meals and food consumption stultifies social and emotional 
needs more often than hunger. Byrd-Bredbenner, Finckenor, and 
Grasso's (2003) study identifies, content analyzes, and describes the 
health-related content (HRC) presented in the top-ranked prime-time 
network programs for the age 2 to 11 year-old category. Results 
reveal that viewers see one HRC-containing scene approximately every 
four minutes; foods and alcoholic beverages are frequently shown and 
consumed; in most scenes, the HRC portray negative health behaviors.
Cultivation effect
With the food-related media content analyzed and understood, numerous 
studies have revealed the relation between exposure to food-related 
media content and children's food preferences and nutritional 
knowledge with ample empirical evidence. Positive relationships 
between heavy television viewing and poorer nutrition knowledge have 
been found, even controlling for other factors that might be related 
to either heavy viewing or low knowledge, such as parent education, 
child's reading level, and socio-economic status; heavy television 
viewing and/or more-frequent exposure to low-nutrition foods also is 
found related to children' preference for unhealthy foods and to poor 
eating habits (Brown & Wash-Childers, 2002).
Several of these studies were conducted in the tradition of 
cultivation analysis, with the assumption that television dominates 
the symbolic environment of children's life. These studies sought to 
ascertain if there is a relationship between television viewing and 
having views of the world that are more reflective of the images seen 
on television than those in fact.  From the perspective of 
cultivation theory, Signorielli and Lears (1992) examined children's 
conceptions about nutrition as revealed in their answers to survey 
questionnaires. Two hypotheses were tested: 1. The relation between 
watching television and having poor eating habits is positive; 2. The 
relation between watching television and having unhealthy conceptions 
about food and the principles of nutrition is positive. In operation, 
"watching television" was measured by "daily television-viewing 
time." There were two sets of questions in the survey related to 
eating habits (e.g., "how often do you eat a snack each day?") and 
conception about food and nutrition (e.g., "which of the following is 
the best example of a nutritious breakfast, a glass of orange juice 
and a bowl of cereal with milk, three pancakes and three pieces of 
cinnamon toast, or a glass of apple juice and two pieces of toast?"), 
the children's answers to which were combined into an additive index 
as measurement for the "eating habits" variable and the "conception 
of nutrition" variable. A strong positive relation was found between 
watching more television and giving answers to these questions that 
reflect poor knowledge of nutrition, and having bad eating habits 
(e.g., eating sugared cereal for breakfast, frequently eating at a 
fast food restaurant, frequently eating sugared or fat-laden salty 
snacks, and frequently drink soda or sweetened fruit drinks). To shed 
further light on the relation between watching more television and 
children's conceptions about nutrition, Signorielli and Staples 
(1997) expanded and replicated the 1992 study, finding that the more 
television the children watched the more likely they were to select 
an unhealthy food when choosing which foods they would rather eat, 
which is consistent with cultivation theory assertions.

Alternative Explanations of the Role of Media in Obesity
	As cultivation theory has its weaknesses, such as overgeneralizing 
media audience, and overgeneralizing media content, the theories of 
social learning and priming can offer complement explanations for the 
media effects on childhood obesity.
According to social learning theory (Bandura, 2002), children learn 
by observing the behavior of others and the outcomes of those 
behaviors; one major source of observed behavior is the mass media, 
specifically television; media characters who serve as models may be 
attended by children and, depending whether their eating behaviors 
are rewarded or punished, they would either disinhibit or inhibit 
children's imitation of the behavior respectively.
According to the theory of priming (Roskos-Ewoldsen, Roskos-Ewoldsen, 
& Dillman-Carpentier, 2002), media, whose ubiquitous nature in 
people's lives makes it a powerful tool for priming how they think 
and believe, influences their later judgments and behavior. As 
applied from the field of cognitive and social psychology to the 
media, priming refers to the effects of the media content on people's 
later behavior or judgments related to the content. For example, 
media can prime aggressive thoughts and feelings, aggressive 
behaviors, the information and criteria that people use in making 
judgments of political figures, and various stereotypes that 
influence how people make judgments of other people from the 
stereotypes group (Roskos-Ewoldsen, Roskos-Ewoldsen, & 
Dillman-Carpentier, 2002). In other words, the food-related content 
in media can powerfully influence children's later conceptions and 
judgments of food and nutrition, and their eating behavior.
No individual research works so far, however, were found from the 
literature to study the role of media in childhood obesity from 
either a social learning or priming perspective.

Hypotheses, Model, and Future Research
In accordance with previous childhood obesity studies and cultivation 
theory principles, the role of media in childhood obesity can be 
hypothesized as the followings:
H1: The more time children spend using media, the greater their BMI 
percentiles.
H2: There is a negative relationship between children's amount of 
time spent using media and amount of time they spend on physical activity.
H3: Children who spend more time with media are more likely to have 
nutrition misconceptions.
H4: Children who spend more time with media have less healthy dietary habits.
What is worth noting is that the existing literature on the topic has 
mostly examined television only when dealing with media as a 
contributor to obesity.  Few studies have paid attention to the 
computer screen.  In fact, since 1995, the so-called "year of the 
Internet," the Internet has revolutionized people's lives in many 
aspects.  In addition, playing computer games is popular among 
children. By now, the computer screen is by no means a less 
significant role than television screen in children's daily 
life.  Considering television only cannot reflect the reality 
sufficiently.  It is necessary, therefore, to take Internet and 
computer games into account in our research.  Does the computer 
screen have a similar role in childhood obesity as television 
screen?  Do children nowadays spend more time on computer than on 
television?  Is there a relationship between children's computer use 
time and their physical activity time?  Are children who spend more 
time on TV, computer games, and the Internet more likely to have 
unhealthy dietary habits and nutrition misconception? Future research 
should combine the Internet, computer games with television, 
constituting new definitions of media use and effect concepts.  For 
example, "amount of time spent using media" means "amount of time 
spent on the Internet, computer games, AND watching television".
As a conclusion of previous research, and a guide for future 
research, a diagram of the hypothetical model for the role of media 
in childhood obesity is hereby presented:


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