Research is currently mixed-- and therefore inconclusive-- on the existence of a precise causal connection [1] between exposure to media violence present in virtual gaming and the committing of real-world acts of aggression & violence.

But in fact, a still relevant, authoritative study titled Youth Violence: What We Need to Know [2] declared that sample testing our way to that point is not possible:

“Empirical studies could never be conducted that demonstrate causal connections between exposure to media aggression and rampage shootings”—it explained.

Despite this limitation, some video game researchers, the video game industry itself and the U.S. Supreme Court assert this level of causation needs to exist for them to recognize a relationship between virtual and actual violence.  

Within the field of video game research, there are scores of seasoned experts on youth violence who recognize behavioral issues of young people identified as problem video gamers.

Among them are the likes of Brad Bushman and Craig Anderson who, together with a group of scholarly colleagues, have issued studies and reports on an array of social problems that have stemmed from youth practice of video gaming for decades.

”We conclude that although exposure to violent media is not “the” cause of aggressive and violent behavior, it is an important risk factor that can contribute to more aggressive and violent behaviors, and fewer prosocial behaviors,” the pair wrote in Understanding Causality in the Effects of Media Violence.

According to this approach, one input combines with other inputs to bring about a certain outcome, and the impact of any one input is less measurable given the mix of other inputs it combines with to produce the result.

Multiple contributing factors as a causal source are recognized in addictive patterns, medical diseases and situations producing automobile accidents, as examples.

Causality

[1] Strict causal attribution in which one input is believed to bring about one output in every case. 

[2] Youth Violence: What We Need to Know Report of the Subcommittee on Youth Violence of the Advisory Committee to the Social, Behavioral and Economic Sciences Directorate, National Science Foundation (February 1 and 2, 2013)

Above subcommittee comprised of: Co-Chairs Brad J. Bushman (The Ohio State University) and Katherine Newman (Johns Hopkins University); Participants: Sandra Calvert (Georgetown University), Geraldine Downey (Columbia University), Mark Dredze (Johns Hopkins University), Michael Gottfredson (University of Oregon), Nina G. Jablonski (Pennsylvania State University), Ann Masten (University of Minnesota), Calvin Morrill (UC-Berkeley), Daniel B. Neill (Carnegie Mellon University), Daniel Romer (University of PA), Daniel Webster (Johns Hopkins University).

[3] Ibid.