I think the primary bias in journalism is simply what is chosen to be covered or not covered and how much. And that's one you can't get rid of because the amount of space is generally limited in some way. And it doesn't split neatly down any kind of ideological lines as much as what draws people's attention. Even an upfront ideological bias like Fox News all but admits to still depends on what they choose to cover, they can be anti-immigration for example but only run one story a hour because it's a big event or it "bleeds so it leads." Or they can run a thousand stories a day about every immigration thing they come across*. That shapes and influences their readers probably even more than the anti-immigration stance does, which I imagine has more to do with why the consumers choose that outlet in the first place, mostly by giving the impression of the topic being immediate or important.
edit: Actually, let me take another stab at that last point. With the BLM protests, you can paint them as riots and still show them only when someone gets killed for example. Or you can paint them as riots and lead off every broadcast* with thousands of images culled from months of footage and play up every little thing as the hordes are literally outside this second*. Ideologically, the bias splits mostly the same, against the protests and regarding them as riots. But the bias in the selection of coverage is drastically different and if it's all we cover, no matter how we cover them, people will assume an intensity in the story that it may not warrant. Compared to if we covered it and nine other things happening at the same time. Even if we distorted it ideologically to an even greater extent*.
I do agree with people who suggest that maybe there's more time in our bubbles these days, but I think one factor is simply there's more "news" in general available. Live global coverage of events dates back roughly 25 years or slightly more. Something like Twitter is just over a decade old and mainstream only in the last five years or so.
50 years ago if these protests were happening there would be a few sources that you could turn to. Now I can watch them in real time streaming on the internet from a source. Then watch replays of every night for days from multiple sources if I want to. Then watch random YouTubers try to explain and break down events. And I'll still not be able to get to 50% of the sources on these. It's even worse if I'm trying to follow an event in another part of the world in another language.
I've gone far afield of your original point, Cindi, but to come back to it, I think it's maybe less that we're seeing a more partisan media and instead a more democratic media, it's not a professional elite necessarily anymore, even within partisan or ideological bubbles. I can totally and completely ignore Ben Shapiro and still have hundreds of similar conservative sources if I want the same message he puts out. Same goes for any other kind of coverage almost. When we had three TV stations, a local newspaper and a couple national newspapers and news magazines, there wasn't that.
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