Vallone, R.P., Ross, L., & Lepper, M. R. The hostile media phenomenon: Biased Perception and Perceptions of Media Bias in Coverage of the "Beirut Massacre". JPSP, 1985, 49, 577-585.

"After viewing identical samples of major network television coverage of the Beirut massacre, both pro-Israeli and pro-Arab partisans rated these programs, and those responsible for them, as being biased against their side".

Preliminary Study: Media Treatment of Carter vs Reagan
During this campaign, one could find editorials claiming that a particular coverage of an event was biased toward both sides. A phone interview just before the election showed that while most felt media coverage was generally unbiased, those who felt is was biased believe it was biased against their candidate.

Media Coverage of the Beirut Massacre: Method

They recruited 144 Stanford students with varying initial views on the Middle East crisesis. They initially filled out questionnaires detailing their initial knowledge of the massacre and general sympathies about the Middle East. They divided the groups into pro-Israeli, pro-Arab, and neutral. They viewed the tapes in groups of 6-12. After viewing they also filled out forms about the objectivity and fairness of the news segments. They idenitfied such things as the % favorable, neutray, and unfavorable references to Israel, and estimate how many neutral viewers would change to more positive or negative views about Israel.

Results
Each side saw the news reports as biased in favor of the other side. Pro-arabs thought the programs applied lower standards to Israel or focused less on Israel's role in massacre. The pro-Isarael group saw exactly the opposite. Both felt the personal views of the news staffs were opposite their own.

Further analysis showed that the two groups actually "saw" different news programs. The pro-Arabs heard 42% opinions favorable to Israel and 26% unfavorable. while the pro-Isaraeli group saw 16% favorable and 57% unfavorable. Besides being perceived differently, the program content was evaluated differently too. It was the more knowledgable subjects that felt the media was biased against them, because they had more information with which to find discrepancies.