Failure to Express Sincere Gratitude

Thanking a person who helps you motivates additional prosocial behavior. 

Research shows that the expression of gratitude motivates the helper to help you again, as well as to pay it forward and help third parties. 

This chain of reciprocity breaks when we fail to say thank you or give only faint thanks. 

Expressing thankfulness is an essential part of the giving-receiving cycle. Your expression doesn’t have to be effusive but it does have to be sincere.