Some of this is due to the format. When Perry attacks Romney, Romney gets an additional 30 seconds speaking time. When Romney and Bachmann each attack Perry, Perry gets an additional minute of speaking time. Add up all these additionals rebuttals after personal attacks, and the numbers are bound to favor the challenged frontrunners disproportionately. No one is attacking Ron Paul because no one could pull any votes away from Ron Paul; it would be a fruitless effort. That's less an indication of media bias than it is of good politics on the part of the GOP field.
I'd be more interested to see how many direct questions each candidate received from the moderators not including rebuttal remarks from other candidate's attacks.
http://www.dawnoftheweak.com/2011/09/fox-news-google-debate-9222011.html
[TABLE="width: 236"]
[TR]
[TD="width: 59"][/TD]
[TD="width: 57"]Questions[/TD]
[TD="width: 59"]Responses[/TD]
[TD="width: 61"]Follow-ups[/TD]
[/TR]
[TR]
[TD]Perry[/TD]
[TD="align: right"]8[/TD]
[TD="align: right"]4[/TD]
[TD="align: right"]1[/TD]
[/TR]
[TR]
[TD]Romney[/TD]
[TD="align: right"]8[/TD]
[TD="align: right"]5[/TD]
[TD="align: right"]2[/TD]
[/TR]
[TR]
[TD]Bachmann[/TD]
[TD="align: right"]7[/TD]
[TD="align: right"]1[/TD]
[TD="align: right"]0[/TD]
[/TR]
[TR]
[TD]Gingrich[/TD]
[TD="align: right"]7[/TD]
[TD="align: right"]0[/TD]
[TD="align: right"]0[/TD]
[/TR]
[TR]
[TD]Cain[/TD]
[TD="align: right"]7[/TD]
[TD="align: right"]0[/TD]
[TD="align: right"]0[/TD]
[/TR]
[TR]
[TD]Santorum[/TD]
[TD="align: right"]7[/TD]
[TD="align: right"]1[/TD]
[TD="align: right"]1[/TD]
[/TR]
[TR]
[TD]Ron Paul[/TD]
[TD="align: right"]6[/TD]
[TD="align: right"]0[/TD]
[TD="align: right"]0[/TD]
[/TR]
[TR]
[TD]Huntsman[/TD]
[TD="align: right"]6[/TD]
[TD="align: right"]2[/TD]
[TD="align: right"]1[/TD]
[/TR]
[TR]
[TD]Johnson[/TD]
[TD="align: right"]5[/TD]
[TD="align: right"]0[/TD]
[TD="align: right"]0[/TD]
[/TR]
[TR]
[TD]Total[/TD]
[TD="align: right"]61[/TD]
[TD="align: right"]13[/TD]
[TD="align: right"]
5[/TD]
[/TR]
[/TABLE]