Meta-analysis. A complete description of the techniques of meta-analysis is beyond the scope of this book. For our purposes, meta-analysis is defined as the quantitative aggregation of many research findings and their interpretations. It allows researchers to draw general conclusions from an analysis of many studies that have been conducted concerning a definable research topic. Its goal is to provide a synthesis of an existing body of research. Given the large number of research studies that have been conducted concerning antisocial and prosocial behavior, it is not surprising that the mid- to late-1990s saw the growth in popularity of meta-analytic research in this area. Five examples of meta-analysis are discussed here.
Paik and Comstock (1994) performed a meta-analysis on 217 studies from 1959 to 1990 that tested 1,142 hypotheses. They concluded that the magnitude of the impact of exposure to media violence varied with the method used to study it. Experiments produced the strongest effects, and time-series studies the weakest. Nonetheless, there was overall a highly significant positive association between exposure to portrayals of violence and antisocial behavior. In addition, they found that males were affected by exposure to media violence only slightly more than females and that violent cartoons and fantasy programs produced the greatest magnitude of effects. The latter finding is at odds with the conventional argument that cartoon violence does not affect viewers because it is unrealistic.
A second meta-analysis on the impact of exposure to pornography and subsequent aggressive behavior was done by Allen, D’Alessio, and Brezgel (1995). They analyzed the results of 30 studies and found that there was indeed a connection between exposure to pornography and subsequent antisocial behavior. More specifically, they noted that exposure to nudity actually decreased aggressive behavior. In contrast, consumption of material depicting nonviolent sexual activity increased aggressive behavior, while exposure to violent sexual activity generated the highest levels of aggression. These findings are in accord with those discussed by Paik and Comstock (1994). A meta-analysis of studies examining exposure to pornography and acceptance of rape myths (Allen, Emmers, Gebhardt, & Geiry, 1995) revealed that experimental studies showed a positive relationship between pornography and rape myth acceptance but nonexperimental studies displayed no such effects.
Friedlander (1993) reported the results of a meta-analysis that compared the magnitude of effects reported by studies that looked at antisocial behavior with those that examined prosocial behavior. He found that, with few exceptions, the effects found for prosocial media messages were larger than the effect found for antisocial messages. Finally, Hogben (1998) looked at the results of 56 analyses from 30 studies and concluded that viewing televised violence was associated with a small increase in viewer aggression. In addition, there was a correlation between the year a study was done and the effect size; the later the study, the greater the effect size, suggesting that prolonged exposure has a greater effect on viewers. Last, justified violence and violence that did not accurately portray the consequence of violence generated greater effect sizes.