According to Harvard University, psychological studies consistently find a link between gratitude and happiness. People who feel and express gratitude are more likely to maintain strong senses of optimism and overall well-being. These people also enjoy better physical health, and are more likely to exercise than those without senses of gratitude [source: Harvard Medical School].

Unfortunately, not everyone sees gratitude in such a positive light. The philosopher Nietzsche referred to gratitude as a power struggle where a "powerful man (is) weakened by kindness." This may seem like an extreme attitude, but studies have shown that it's also a fairly accurate depiction of the way in which many men respond to favors or kindness.

 In a 1995 study, researchers found that men were more likely than women to associate gratitude with negative feelings such as dependency and indebtedness. These feelings of being in debt to others led men to not only express less gratitude, but also to feel less thankful than women [source: Emmons]. This idea was reinforced once again in 2010, when researchers performed a gratitude study on couples in romantic relationships. The study concluded that small acts of kindness can boost relationships, but scientists also found that men were much more likely than women to associate these acts with a combination of gratitude and indebtedness [source: Algoe et al].

Some researchers suggest that emotional intelligence may be to blame for the difference in how men and women perceive gratitude. Studies often suggest that women have a greater sense of empathy than men, which makes them better equipped to perceive the thoughtfulness behind an action. Men, on the other hand, lack the skills required to truly grasp this thoughtfulness, and may be left questioning the motivations of others [source: Algoe et al]. 

Although these studies seem to show that the male sex is at a disadvantage when it comes to grasping the concept of gratitude, new research suggests that this may not be the case. In 2011, a study at Eastern Washington University measured two different types of gratitude in men and women. They found that women were more likely to possess trait gratitude, or a disposition toward this emotion, but that there was little difference between the sexes in terms of state gratitude, or feelings of gratitude in a particular moment [source: Pichinevskiy]. This study shows that modern man may have managed to overcome his instincts, giving himself the opportunity to enjoy the same gratitude-related happiness as the fairer sex.

Research carried out at George Mason University found that men have a more difficult time with gratitude than women do [source: ScienceDaily]. Blame it on their feeling of having to return the favor when they receive a gift. Or it could be a discomfort with feeling emotional or maybe vulnerable by having to admit they may have needed some help. Whatever the reason, men do not feel as comfortable with gratitude in general.