A study published in Personality and Social Psychology Bulletin proposes that people often refrain from giving compliments because they mis-predict how their compliments make others feel. 

Giving compliments to others requires little effort, while having great results for both parties. While you gain the satisfaction of knowing you brighten someone’s day, for the recipient, it can also enhance their performance and activate the reward pathways in their brain. 

So, why don’t people give out compliments more often? There may be two reasons for this. Unsurprisingly, people often feel anxious about interacting with strangers, despite the findings that talking to strangers can leave the complimenter feeling better  than he did before. 

This anxiety can discourage people from giving compliments because they believe that the recipient of their compliment will also feel as anxious and uncomfortable as they do. 

Secondly, people tend to be overly concerned with expressing themselves “just right”. This concern inhibits compliment-giving because people fear their compliment may not come across exactly the way they intended. 

The researchers investigated their hypothesis through a series of experiments. Participants from a U.S. college were assigned a location on campus to perform a task. They were asked to compliment the fourth stranger (of the same gender) that they saw. 

Next they were asked to hand the person a sealed envelope and say, “I’m supposed to give this to you as part of an experiment I’m participating in. I don’t know what’s in it, but I need to wait for you to fill it out and give it back to me.” 

In reality, the envelope contained a short survey assessing how the recipient felt about the compliment. The compliment givers also filled out a similar survey from their perspective. 

The researchers found that in addition to underestimating how positive the recipient of their compliment felt, they also drastically overestimated how bothered, uncomfortable and annoyed the other person felt because of the compliment.

In the following experiment, participants were assigned the role of compliment giver or third-party predictor. Compliment givers were given the same instructions as the last experiment. 

Before leaving the lab to perform their task, the compliment givers were asked to report how competently and skillfully they’d be able to compliment a stranger. They also reported how positive/negative they thought the other person would respond. 

After performing the task at their assigned location on campus, they responded to the same surveys to assess their experience. Participants who were assigned the role of third-party predictors didn’t witness the compliment giving, but the experiment was described to them. 

They responded to the same questions as the compliment givers, to assess how they thought the recipient of the complement would feel. 

The researchers found that compliment givers felt anxious before performing their task, and their anxiety predicted how negatively they thought their compliment would be perceived. 

Second, compliment givers were concerned about their own competence and ability to compliment a stranger. Compared to the compliment givers, the third-party predictors expected the compliment receiver to feel significantly more flattered, pleased and good and significantly less uncomfortable, annoyed and bothered. 

Based on how the recipient of the complement responded to the surveys, the third-party predictor’s estimates were accurate. In fact, one compliment recipient wrote on their survey, “Thanks for making my day more human!”

In addition, compliment givers reported being in a better mood after complimenting a stranger, and said they’d be more likely to give out compliments in the future. 

Overall, the researchers found that people underestimate the positive effects and overestimate the negative effects of complimenting others, especially people they don’t know very well. This may likely be due to anxiety that often manifests when having to interact with strangers. Despite this, giving compliments leaves both parties feeling better than before and increases the likelihood that people will compliment others in the future.

The researchers predicted that these two factors will lead people to misforecast how good their compliments make others feel, thus lowering the likelihood of giving compliments.