The Human BrainHave you ever tried remembering a number of things at one time, only to inevitably forget one of them?

Well, if your like most people, you’re not alone. A new study suggests the average person’s short-term memory can only hold four items at a time.

Psychologists at the University of Oregon researched short-term memory capacity and a possible underlying link to general intelligence (commonly referred to as IQ). They found individual short-term memory capacity varied from person to person, but that memory capacity was a strong indicator of IQ and scholastic aptitude.

They also found people with high IQs could think about more things simultaneously.

One hypothesis psychologists have considered is that memory capacity might be influenced by the complexity of items being stored.

The researchers Edward Awh and Edward Vogel discovered that even when very complex objects had to be remembered, people were able to hold four items in active memory. However, Awh said, the clarity of those items was not perfect, and some people had much clearer memories than others.

“Knowing the number of things a person can remember tells you nothing about how clear a person’s memory may be,” Awh said. “So even though people with high IQs can think about more things at once, there are not guarantees about how good those memories might be.”

The research appears in the July issue of the journal Psychological Science.