In the right hands, a logo can be a designer’s most powerful tool for creating and promoting a brand. However, when all they have to play with are shape and colour, how do they judge the difference between a logo that will be a success and a logo that will be a failure? The answer lies in the subconscious mind of the consumer.

Read more here: http://www.idesigni.co.uk/blog/psychology-of-logo-design/