How Much Can Your Mind Keep Track Of?

March 17, 2005

Cooking shows on TV usually give a Web address where you can find, read, and print out the recipe of the dish created on that day’s show. The reason is obvious: It’s too hard to just follow along with what the chef is doing, let alone remember it all. There are too many directions and ingredients — too many variables and steps in the process to keep track of quickly.
New research shows why it doesn’t take much for a new problem or an unfamiliar task to tax our thinking. According to University of Queensland cognitive science researchers Graeme S. Halford, Rosemary Baker, Julie E. McCredden and John D. Bain of Griffith University, the number of individual variables we can mentally handle while trying to solve a problem (like baking a lemon meringue pie) is relatively small: Four variables are difficult; five are nearly impossible.

Their report, "How Many Variables Can Humans Process?" is published in the January 2005 issue of Psychological Science, a journal of the American Psychological Society.

It’s difficult to measure the limits of processing capacity because most people automatically use problem solving skills to break down large complex problems into small, manageable "chunks." A baker, for example, will treat "cream butter, sugar and egg together" as a single chunk — a single step in the process — rather than thinking of each ingredient separately. Likewise she won’t think, "break egg one into bowl, break egg two into bowl." She’ll just think, "add all of the eggs."

To keep test subjects from breaking down problems into bite-size chunks, researchers needed to create problems that they weren’t familiar with. In their experiment, 30 academics were presented with incomplete verbal descriptions of statistical interactions between fictitious variables, with an accompanying set of graphs that represented the interactions. The interactions varied in complexity — involving as few as two variables up to as many as five. The participants were timed as they attempted to complete the given sentences to correctly describe the interactions the graphs were showing. After each problem, they also indicated how confident they were of their solutions.

The researchers found that, as the problems got more complex, participants performed less well and were less confident. They were significantly less able to accurately solve the problems involving four-way interactions than the ones involving three-way interactions, and they were (not surprisingly) less confident of their solutions. And five-way interactions? Forget it. Their performance was no better than chance.

After the four- and five-way interactions, participants said things like, "I kept losing information," and "I just lost track."

Halford et al concluded from these results that people — academics accustomed to interpreting the type of data used in the experiment problems — cannot process more than four variables at a time. Recognizing these human limitations can make a difference when designing high-stress work environments—such as air-traffic control centers—where employees must keep in mind several variables all at once.

Explore further: Italy, Vajont "tsunami" and Malborghetto-Valbruna floods: different lessons from the past

Related Stories

Researchers show new Ice Age may begin by 2030

July 17, 2015

The arrival of intense cold similar to the weather that raged during the "Little Ice Age", which froze the world during the 17th century and in the beginning of the 18th century, is expected in the years 2030 to 2040. These ...

Scientists update horizontal wind model

July 13, 2015

Scientists at the U.S. Naval Research Laboratory (NRL) have updated the Horizontal Wind Model (HWM) that describes the climate of the upper atmospheric neutral winds. This improved empirical tool will help scientists as they ...

Recommended for you

Dense star clusters shown to be binary black hole factories

July 29, 2015

The coalescence of two black holes—a very violent and exotic event—is one of the most sought-after observations of modern astronomy. But, as these mergers emit no light of any kind, finding such elusive events has been ...

Researchers build bacteria's photosynthetic engine

July 29, 2015

Nearly all life on Earth depends on photosynthesis, the conversion of light energy into chemical energy. Oxygen-producing plants and cyanobacteria perfected this process 2.7 billion years ago. But the first photosynthetic ...

Yarn from slaughterhouse waste

July 29, 2015

ETH researchers have developed a yarn from ordinary gelatine that has good qualities similar to those of merino wool fibers. Now they are working on making the yarn even more water resistant.

Scientists unlock secrets of stars through aluminium

July 29, 2015

Physicists at the University of York have revealed a new understanding of nucleosynthesis in stars, providing insight into the role massive stars play in the evolution of the Milky Way and the origins of the Solar System.

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.