This blog does a good job of summarising the research showing that gratitude and acknowledgement are more powerful motivators than money.  I see this frequently in the teams I work with where members want to focus on what's going wrong. The brain is designed to look for threats and take action and it seems that corporate culture's obsesion with continuous improvement overlooks how people are motivated. 

Gottman's research supports the requirement of 5:1 positive to negative comments in a relationship that will stand the test of time. This research applies to the office as well. 

What's so interesting about giving and receiving acknowledgements is how poor people are in receiving them, and how unskilled they are in giving them. Powerful and meaningful acknowledgement needs to highlight the qualities of the person, and not their output. It's harder than we think, but more rewarding than we realise.