I'm writing an asset inventory resource and have come across a lot of interesting research.  Here's an example:

Ignoring strengths in favor of weaknesses has a profound effect on individual performance, according to a 2002 Corporate Leadership Council survey of nearly 20,000 employees in 29 countries. Emphasis on performance strengths was linked to a 36 percent improvement in performance while emphasis on performance weaknesses was linked to a 27 percent decline in performance.  (from "The Power of Positive Thinking in the Workplace" HR News. 2008 Society for Human Resource Management. http://moss07.shrm.org/Publications/HRNews/Pages/PowerofPositiveThinking.aspx (accessed 3/31/10).

My conviction that this is a key driver of success has been growing.  I wrote about the difference between growing and pruning a few months ago, and just recently posted a video about how this lead to the turn-around of Starbucks.