It may just be a simple gesture but it might help change someone's life. Whether someone decides to return back a favor we did for them might totally be up to us. It may depend on how we specifically helped them when they needed it. This study can be found published in the journal Frontiers in Psychology.

Researchers at the University of Southern California deviced a pair of door-holding experiments to assess whether the amount of effort one gives to another will influence the recipient's tendency to say thank you and in return show their willingness to pay it forward and show some kind gestures to others too, including the one who originally helped them. Those who said thanks, however, weren't as enthusiastic to help out those who helped them, not to mention an unrelated third party immediately after receiving help themselves.  To top it all, the level of effort showed by the original helper didn't spark an interest to the test subjects, to extend that help to others aside from the helper.

According to the authors, the current study focuses on spontaneous social behavior that was measured in a way that will later allow answers about how we feel about the things others do for us, and more importantly, how we act on it. They also added saying that it is their first time to see that verbal thanking and mutual helping did not naturally correlate.

During the first experiment, the researchers developed an unreliably complicated scenario. The condition was set up, with one person opening the door for someone unenthusiastically and with as little effort as possible, pretending to exit the building just a few steps ahead of the unfortunate subject while avoiding eye contact. Another scenario included someone entering the building where the subject was from, holding the door open while waiting for the person to exit, flashing a great big smile and maintaining eye contact. In both cases, the subject would normally be challenged by a second experimenter- which usually has no idea what type of condition the subject had just passed through- outside.

The experiment results revealed that out of 120 test subjects who were suitably approached (each condition had 40 subjects) only 24 extended verbal thanks, however, these people who said thank you were the ones belonging to the high-effort condition. There was also nothing different between groups in terms of their willingness to take the survey, with only 29 out of the 120 subjects that were asked, nor were they interested in how long they chose to stay and answer questions.