I have been having a discussion with one of my clients about their blog avatar. I have always read that you are supposed to have a photo avatar on a blog for various reasons. (instills trust, helps people to recognize you, seems more genuine, etc.) However, they want to put their logo up instead. I have been looking for some good articles that support the photo argument. However, I have not been having any luck.

What's the agreement here? Logo or photo? And does anyone have any links that will show why?

Thanks!