Think of that serial flaker in your friend group who everyone knows not to wait on to get the festivities started. They've developed something of a reputation for not showing. That may be more common among some personality types, says Richard Koestner, a professor of psychology who studies personality and motivation at McGill University in Montreal, Quebec.
"It reflects some narcissism and lack of concern for how people feel. Less of the trait of agreeableness," he notes.
Agreeableness is a personality trait associated with being cooperative and unselfish. Another relevant personality trait, Koestner says, is something psychologists call conscientiousness. The American Psychological Association defines it as "the tendency to be organized, responsible, and hardworking." People who rank low in conscientiousness are more likely to be disorganized, overbook themselves and not follow through — in other words, flake.
Then there's the simply human side of it. You can probably think of a time when you committed to something in the future that, when the time finally came, you just didn't feel like doing it, like starting a diet, or a new spin class — all of those new year's resolutions. In the abstract, the idea of being healthy and fit is appealing. Later on when we actually have to put in the effort, we find that other things have gotten in the way; we're feeling tired or overwhelmed.
The ability to predict your emotional reaction to events in the future is called "affective forecasting." Research shows people generally tend to overestimate the positive aspects of an event they planned in the future.
"The abstract idea is to have a more positive relationship with my friends — taking them to the airport, or helping them move. Yes, I want to be someone who shows up for my friends!" says Tabitha Kirkland, a lecturer at the University of Washington. "On the day of, you're not thinking abstractly, you're thinking of the minute details of what it will take to get there."