Habits are often described as things we do a lot, but Wendy Wood and Dennis Rünger, in their 2016 review “Psychology of Habit” in the Annual Review of Psychology, argue that frequency alone does not make something a habit. A habit is a learned link between a familiar situation and a particular action. Once that link is strong enough, the situation can trigger the action with very little conscious thought. Many people reach for their phone the moment they sit down to relax. After enough repetitions, sitting down alone can bring the urge to check the phone to mind, even if they never decided to do it.
Habits usually begin with a goal. A person wants something, so they repeat an action in a particular setting. Over time, the brain learns the connection between the action and the cues around it, such as the time of day, the place, the people present, or the activity that came just before. Rewards strengthen this learning. Someone who wants to feel more awake might make coffee right after getting out of bed each morning. The goal gets them started, the pleasant result reinforces it, and eventually waking up and making coffee become one connected sequence.
This efficiency is also why habits are hard to change. Habits save us from thinking through every familiar action, but the same automatic quality makes them stubborn. A cue can bring a familiar response to mind even when our goals or preferences have changed. The authors discuss a well-known study by Neal and colleagues, in which regular popcorn eaters at a cinema ate just as much stale, week-old popcorn as fresh popcorn, even though they said they did not like it. The cinema itself had become linked to eating popcorn. The same people ate far less stale popcorn when they were in a different setting, such as a meeting room, which shows how strongly the situation can drive the behavior.
None of this means people have no control over their habits. A habit works more like a default response, which deliberate action and competing goals can sometimes interrupt. That control takes effort, though, and it becomes harder under stress or fatigue. After a draining day, a person who is trying to cut back on snacking may find themselves at the kitchen cabinet anyway, because the habit fills the gap when mental resources run low.
Habits and goals often work together. Goals help a person start a behavior and keep repeating it, and repetition makes the behavior more automatic. Later, the habit lets the person continue the activity without much time or effort, like going for a run every evening without having to decide each time. But habits can also outlast the goal that created them. Because we have done something for a long time, we may assume we do it because we want to. The authors note that people can draw mistaken conclusions about their own motives this way. Someone who has bought a sugary drink at the same stall every afternoon for years may believe they crave it, when the route and the time of day are doing most of the work.
The message of the paper is that changing behavior is not only about deciding harder. It also helps to pay attention to the cues and situations connected to the behavior. To build a wanted routine, repeat the action in a stable, recognizable situation, such as stretching right after brushing your teeth every night. To disrupt an unwanted routine, change or avoid its usual cues, for example by keeping your phone in another room when you sit down to relax, or deliberately practice a different response to the same cue, such as reaching for a book instead.
