Take a look at this quick movie. You’ll be shown a “ready” screen, followed by a quick flash of eight letters arranged in a circle. Your job is to spot either a “Z” or a “K” in that circle of letters, while ignoring other letters appearing outside of the circle.
You’ll see two different circles of letters in the movie. Each circle will either contain a Z or a K. Again, ignore the letters appearing outside of the circle. Go ahead, give it a shot.
Just watch the video once! What order did you see the Z and the K in? Let’s make this a poll.
I don’t expect that we’ll uncover all the nuances of this phenomenon in such a short demonstration, but I think it’s quite probable that most viewers will have correctly identified the letter in the second circle, where the other letters were all “O”. That makes sense — there are fewer distractors, so the problem is easier.
Sophie Forster and Nilli Lavie showed hundreds similar movies to 61 volunteers. As in our demonstration, there were two types of displays. Displays like the first one in our example, where the target letter was displayed next to many different, similarly shaped letters, are clearly more difficult. These are called “high load” displays because they require more perceptual resources to process. Displays like the second one in our demo are called “low load.” Again, as in our demo, viewers were looking for one of two possible letters.
As expected, viewers responded significantly slower and made more errors with high-load displays than with low-load displays. But that wasn’t the question Forster and Lavie were interested in. What they wanted to know is how different types of people responded to the different displays.
In previous research, Lavie and others had found that some people are more distractible than others. The trait can be measured with a simple questionnaire asking questions like “how often do you start doing one thing and then get distracted by something else,” and “how often do you accidentally throw away something you want and keep what you meant to throw away (like throwing a full box of matches in the trash and putting the ember in your pocket).” High scores on this measure (called the the CFQ) are associated with higher car-accident rates and accidents at work.
You might expect that people with high CFQs would do poorly on tests like the one in the movie. You’d be right — but only partly right. Their results were different in a critical way based not just on the letters in the circle with the target letter, but the distractor letter outside the circle. When that letter was the same as the target letter, everyone was faster and more accurate. But there was a key difference, summarized in this graph:
In the simpler (low-load) task, with only one distractor, the distractor was significantly more distracting to people with high CFQs. But in a high-load task, CFQ made no difference, and the distractor affected everyone equally.
So everyone benefits from having fewer distractions, but more distractible people don’t benefit as much. So it may be the case that when taking a test in a quiet room, highly distractible people are going to be more adversely affected by something like a barely-audible conversation in the hallway. If there are lots of distractions, like in a noisy coffee shop, everyone will be affected roughly equally. This might explain why, in college, I preferred to study in noisy coffee shops, while Greta favored studying in the quietest library on campus.
Sophie Forster, Nilli Lavie (2007). High Perceptual Load Makes Everybody Equal: Eliminating Individual Differences in Distractibility With Load Psychological Science, 18 (5), 377-381 DOI: 10.1111/j.1467-9280.2007.01908.x