When I’m writing a post for Cognitive Daily (or doing almost any kind of writing, for that matter), I try to keep outside distractions to an absolute minimum. I even have an application on my computer that shuts off all access to the internet for a specified period of time. I find most music distracting, but sometimes I’ll play a Mozart piano concerto, which seems to help focus my attention (see here for a possible explanation).
Some people, however, seem to be able to be incredibly productive despite a huge number of distractions — Twitter status updates, email, crying babies, you name it. Indeed, some people can’t work well if things are too quiet. For them, uninterrupted silence is more distracting than cacophony.
But whatever their working environment, it’s clear that some people are simply better at focusing on the task at hand. What makes people’s minds more or less likely to wander? Several studies point to working memory capacity as the key. While on average people can keep about 6 or 7 words or numbers in memory, capacity varies from individual to individual. People with higher working memory capacity tend to do better on tasks like the sustained attention to response task (SART) which demand focused attention to a task. We discuss the SART in more detail here, with a video example.
Working memory might seem unrelated to such a simple task as SART: Usually you’re asked to do something like respond only to words NOT beginning with the letter “P”, while dozens of words flash by and only the occasional “P” word. You’ve only got to focus on one thought at a time — why should it matter whether your working memory capacity is 5 or 8?
Jennifer McVay and Michael Kane believe it’s because having a larger working memory capacity means you’re better able to focus on the task at hand. To confirm their hunch, they tested hundreds of students on both working memory size and their ability to do the SART task (they used several different rules, but we’ll focus on the task where viewers had to respond when a word was in lowercase, but not when it was in ALL CAPS — which only occurred about 10 percent of the time). There was one additional twist to their study. After some of the key all-caps words appeared (and the students either incorrectly pressed the space bar, or correctly resisted), the students were asked what they had been thinking about during the task:
- The task itself
- How well they were doing on the task
- Their daily life
- Their current state of being (hungry? tired?)
- Worries, concerns, or fears
- Daydreams
- Other
The SART test was given in four blocks of 450 words, of which 50 were in all caps. As you might expect, thoughts tended to wander as the experiment progressed:

Thoughts unrelated to the task increased dramatically by the end of the study, while task-related thoughts declined. Thinking unrelated thoughts correlated significantly (r = .368) with poor performance on the task. And unrelated thoughts were negatively correlated with working memory capacity (r = -.217).
So having a low working memory capacity is associated with increased tendency for your thoughts to wander. And as in previous studies, it’s also correlated with poorer performance on the task. McVay and Kane say this means having a large working memory capacity results in a better ability to focus your thoughts, thus avoiding distracting thoughts and staying on-task.
This isn’t to say that having unrelated thoughts makes the task impossible — despite thinking unrelated thoughts, respondents still made the correct response 42 percent of the time. While they were focused on the task, the students made an incorrect response 34 percent of the time, so other factors were involved. But a high working memory capacity and keeping focused on the task were the most reliable predictors of success.
One more thing: While reading this study I found it very hard to stay focused. Maybe it’s just because we’re dealing with an unusual late snowstorm in the southern U.S., but maybe the process of thinking about how we deal with distractions is inherently subject to additional distractions. Did you have a similar experience? Let’s make this a poll:
Jennifer C. McVay, Michael J. Kane (2009). Conducting the train of thought: Working memory capacity, goal neglect, and mind wandering in an executive-control task. Journal of Experimental Psychology: Learning, Memory, and Cognition, 35 (1), 196-204 DOI: 10.1037/a0014104