In a new study, cognitive scientists show that humans can usually track just four mental variables when trying to solve a problem. In the journal Psychological Science, cognitive scientists from the University of Queensland and Griffith University report on a study where they tested these limits of processing capacity. It's tough to measure because people commonly break down complex problems into manageable chunks. For example, a baker doesn't have to think: "break egg one into bowl, break egg two into bowl, etc." Instead, he'll track it as one chunk: "add all the eggs." To measure their test subjects, the researchers devised problems involving statistical interactions between fictitious variables. The details of the test are vague, but apparently the problems couldn't immediately be broken into "bite-size chunks." From the press release:
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."
