Does an Author Photo in SERPs Increase CTR?

+Matt McGee in a post today asked if there were any "definitive studies" demonstrating the oft-repeated alleged benefit of the Authorship rich snippet. +Max Minzer and +AJ Kohn responded with links to three they of which they were aware. I thought it would be useful to share them here:

"How Optimizing My Ugly Google+ Photo Increased Free Traffic 35% (by +Cyrus Shepardhttp://goo.gl/8jQbX

"What Makes for a Good Author Photo in the Local Search Results?" (by +Mike Blumenthal) http://goo.gl/t66iW - this one isn't really a CTR study, but rather uses survey data to gauge how uses react to different faces in a search for a lawyer.

"Click Through Rate Increased 38% with Rel Author" (by +Russell Jensen)  http://goo.gl/x5A6y

"How Rich Snippets Can Improve Your CTR" (by +Catalyst) http://goo.gl/xPXaW
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