Studying Habits by Changing Them

An important insight about habits is that they are activated by triggers in the environment. These triggers can be people or places, events or the time of day. The important idea is that we have learned to respond to something outside of us (i.e., the trigger) with a specific behavior (the habit). Let’s look at a set of studies by Wendy Wood, David Neal, and their colleagues. This is just one of many studies of habits that these and other researchers have conducted, but it will give you an idea of how we can learn more about psychological processes by manipulating the details of a common event to see how people’s behavior changes.

The Popcorn Study

Movie theater attendance is on the decline in the United States, but going to the movies is still popular. Of course, we go to the theater to see the movie, but for many people the experience is just not complete without the right refreshments: popcorn, candy, and soft drinks. You may be too health-conscious to buy these snacks, but most movie theaters depend on their concession stands to stay open.^[1] Eating popcorn in a movie theater is a great example of a habit: a behavior that is triggered by a particular setting—the movie theater.

In 2011, David Neal, Wendy Wood, and some of their students published a study in which they used the movie theater-popcorn connection to study habitual behaviors.^[2] They looked for evidence that movie theaters really do trigger eating popcorn. But checking out the validity of that claim was just the starting point for studying the popcorn habit.

The Setup

The experiments were conducted on the campus of the University of Southern California (USC). The campus has a cinema that regularly shows films that are popular among students.^[3] They recruited students and assigned them to one of two conditions:

1. In the cinema condition, the students went into the theater before the regular movie started and they watched and rated movie trailers. The important thing to understand is that the setting looked, sounded, smelled, and felt like a movie theater (which, of course, it was).
2. Other students were recruited to come, at the same time of day, to a meeting room near the movie theater. These students were asked to listen to watch and rate music videos. The music videos had been pretested to assure that they were as interesting and engaging as the movie trailers that the cinema group watched. For this meeting room condition, the room was as comfortable as the theater and the task was as engaging as the one in the theater, but the location did not look or sound, smell or feel like a movie theater. It was a meeting room.

Next came the critical prop for this experiment: a full box of popcorn was given to each person, along with a cup of water. No one made a big deal about the popcorn, but (unknown to the participants) the main question was: how much popcorn would people eat?

Where do you think the participants ate more popcorn: in the cinema or in the meeting room? Move the bars below to give your estimate of the percentage of the box of popcorn (this is the percentage number on the Y-axis) that was eaten—on the average—by the participants in each location.

Click here to see the results.

The first question was the easy one. But we left out a crucial piece of information: half of the participants in each location had nice fresh popcorn, but the other half had rubbery, stale popcorn. Now, how much fresh or stale popcorn do you think participants ate in the two locations?

Now adjust the bar graphs to give your estimate of the percentage of the box of popcorn that was eaten—on the average—by the participants in each location. Brown represents stale popcorn and yellow represents fresh popcorn.

Click here to see the results.

To interpret the results, look at the size of the difference between the brown (stale popcorn) bar and the yellow (fresh popcorn) bar. A bigger difference means that the participants were more influenced by the taste of the popcorn. A smaller difference means that the stale versus fresh popcorn didn’t influence their behavior so much—or, in other words, that habit was more powerful than taste. As you can see, in the cinema—the habitual place to eat popcorn—subjects not only ate more popcorn, but they were less influenced by the quality of the popcorn. This is exactly what you would expect if people are engaging in a learned behavior rather than responding to factors that generally influence how much we eat—such as how good the food tastes.

Now perhaps the people in the cinema just didn’t notice that the stale popcorn was stale. Fortunately, the experimenters anticipated that question, so they asked the students to rate the taste of the popcorn. Here is what they found:

There was no statistically significant difference in the ratings between the cinema and meeting room groups. But notice that, if anything, the cinema subjects rated the stale popcorn tasted as being slightly worse than the meeting room subjects did. The subjects in the cinema knew that the stale popcorn tasted bad, but they still ate it.

Are we sure that habit had something to do with this behavior? The experimenters asked participants to rate the strength of their own habit of eating popcorn in movie theaters. Of course, some people didn’t like popcorn much, while others wouldn’t think of going to the movies and skipping the popcorn. The experimenters divided the participants into three groups, based on their ratings of the strength of their popcorn-at-the-movies habit. Here is what they found for the subjects in the cinema condition:

On average, the three groups ate about the same amount of popcorn. But—once again—notice the difference between the brown (stale) and yellow (fresh) bars. Participants with weak movie-popcorn habits ate a lot of the fresh popcorn, but not much of the stale popcorn. The stale-fresh difference was smaller for the medium movie-popcorn habit group. And, for the students with a strong movie-popcorn habit, there was no significant difference in the amount of fresh versus stale popcorn consumed (with slightly more stale popcorn than fresh actually eaten!). The students with strong habits knew that the stale popcorn was nasty, but they still ate it as if it were fresh.

What do you think happened in the meeting room? You already know that they ate less popcorn in general, and that they ate less stale popcorn than fresh. But did habit strength affect them as much as it did for the folks in the cinema? Make your prediction using the bars below.

Click here to see the results.

Students with stronger cinema-popcorn habits did eat slightly more popcorn overall than those with weaker habits, but look at the DIFFERENCE between the two bars at each habit level. At all three habit strengths, participants ate about the same amount LESS stale popcorn than fresh. This is the sort of thing that people do when they are aware of the food they are eating. If something tastes good, you eat it. If something tastes bad, you leave it in the box.

These results are consistent with the idea that the cinema environment triggers the popcorn-eating habit. The habitual popcorn eater consumes popcorn in the triggering environment (here, the cinema setting) even if the popcorn is not worth eating. In a different environment (the meeting room) the habit is not triggered, so popcorn consumption is much more determined by its quality, regardless of the strength of that habit in the cinema setting.

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