I think we must differentiate between writing on a variety of topics and brand building.
If you want to build your brand in the field of psychology, you better are a psychologist, who offers unique insights and valuable info to readers. Then you create blogs, articles, press releases, guest posts, videos, etc....in other words, you work hard for a few years to establish your brand.
Just writing about psychology schools and degrees makes you nothing but one of thousands of internet marketers, who try to cash in on some AdSense clicks. No branding necessary, or even possible, here.
As online writers/marketers, we try to build our brand as authoritative content creators; usually on a variety of topics, but always knowledgeable and quality-oriented. If we have enough interesting stuff to say on one specific topic, then there's nothing wrong with having a separate account for that.
However, even with only one account we have plenty of "real" branding tools:
- establish credibility through our profile picture and blurb
- categorize consistently so readers can find related content through our profile categories
- list our other related articles on each page
- write often and write well (thanks, JoHarrington!)
- make use of multimedia; there are tons of free tools to create interesting slide shows, graphics, and videos
- use social media and bookmarking
What else can you think of that's useful for our brand building?